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java.lang
Class String
java.lang.Object
+--java.lang.String
All Implemented Interfaces:Comparable,Serializable
----public final classStringextendsObjectimplementsSerializable,[ComparableThe] String class represents character strings. All string literals in Java programs, such as "abc", are implemented as instances of this class.
Strings are constant; their values cannot be changed after they are created. String buffers support mutable strings. Because String objects are immutable they can be shared. For example: String str = "abc";
is equivalent to: char data[] =
String str = new String(data);
Here are some more examples of how strings can be used: System.out.println("abc");
String cde = "cde";
System.out.println("abc" + cde);
String c = "abc".substring(2,3);
String d = cde.substring(1, 2);
The class String includes methods for examining individual characters of the sequence, for comparing strings, for searching strings, for extracting substrings, and for creating a copy of a string with all characters translated to uppercase or to lowercase.
The Java language provides special support for the string concatentation operator ( + ), and for conversion of other objects to strings. String concatenation is implemented through the [StringBuffer] class and its append method. String conversions are implemented through the method toString, defined by Object and inherited by all classes in Java. For additional information on string concatenation and conversion, see Gosling, Joy, and Steele, The Java Language Specification.
Since:JDK1.0See Also:Object.toString(),[StringBuffer],[StringBuffer].append(boolean),[StringBuffer].append(char),[StringBuffer].append(char[]),[StringBuffer].append(char[], int, int),[StringBuffer].append(double),[StringBuffer].append(float),[StringBuffer].append(int),[StringBuffer].append(long),[StringBuffer].append(java.lang.Object),[StringBuffer].append(java.lang.String),Character encodings,Serialized Form
| Field Summary | |
| static Comparator | CASE_INSENSITIVE_ORDER Returns a Comparator that orders String objects as by compareToIgnoreCase. |
| Constructor Summary |
| String() Initializes a newly created String object so that it represents an empty character sequence. |
| String(byte[] bytes) Construct a new String by converting the specified array of bytes using the platform's default character encoding. |
| String(byte[] ascii, int hibyte) Deprecated. This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a character-encoding name or that use the platform's default encoding. |
| String(byte[] bytes, int offset, int length) Construct a new String by converting the specified subarray of bytes using the platform's default character encoding. |
| String(byte[] ascii, int hibyte, int offset, int count) Deprecated. This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via the String constructors that take a character-encoding name or that use the platform's default encoding. |
| String(byte[] bytes, int offset, int length,String enc) Construct a new String by converting the specified subarray of bytes using the specified character encoding. |
| String(byte[] bytes,String enc) Construct a new String by converting the specified array of bytes using the specified character encoding. |
| String(char[] value) Allocates a new String so that it represents the sequence of characters currently contained in the character array argument. |
| String(char[] value, int offset, int count) Allocates a new String that contains characters from a subarray of the character array argument. |
| String(String original) Initializes a newly created String object so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string. |
| String([StringBuffer] buffer) Allocates a new string that contains the sequence of characters currently contained in the string buffer argument. |
| Method Summary |
| char | charAt(int index) Returns the character at the specified index. |
| int | compareTo(Object o) Compares this String to another Object. |
| int | compareTo(String anotherString) Compares two strings lexicographically. |
| int | compareToIgnoreCase(String str) Compares two strings lexicographically, ignoring case considerations. |
| String | concat(String str) Concatenates the specified string to the end of this string. |
| static String | copyValueOf(char[] data) Returns a String that is equivalent to the specified character array. |
| static String | copyValueOf(char[] data, int offset, int count) Returns a String that is equivalent to the specified character array. |
| boolean | endsWith(String suffix) Tests if this string ends with the specified suffix. |
| boolean | equals(Object anObject) Compares this string to the specified object. |
| boolean | equalsIgnoreCase(String anotherString) Compares this String to another String, ignoring case considerations. |
| byte[] | getBytes() Convert this String into bytes according to the platform's default character encoding, storing the result into a new byte array. |
| void | getBytes(int srcBegin, int srcEnd, byte[] dst, int dstBegin) Deprecated. This method does not properly convert characters into bytes. As of JDK 1.1, the preferred way to do this is via the getBytes(String enc) method, which takes a character-encoding name, or the getBytes() method, which uses the platform's default encoding. |
| byte[] | getBytes(String enc) Convert this String into bytes according to the specified character encoding, storing the result into a new byte array. |
| void | getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) Copies characters from this string into the destination character array. |
| int | hashCode() Returns a hashcode for this string. |
| int | indexOf(int ch) Returns the index within this string of the first occurrence of the specified character. |
| int | indexOf(int ch, int fromIndex) Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index. |
| int | indexOf(String str) Returns the index within this string of the first occurrence of the specified substring. |
| int | indexOf(String str, int fromIndex) Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. |
| String | intern() Returns a canonical representation for the string object. |
| int | lastIndexOf(int ch) Returns the index within this string of the last occurrence of the specified character. |
| int | lastIndexOf(int ch, int fromIndex) Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index. |
| int | lastIndexOf(String str) Returns the index within this string of the rightmost occurrence of the specified substring. |
| int | lastIndexOf(String str, int fromIndex) Returns the index within this string of the last occurrence of the specified substring. |
| int | length() Returns the length of this string. |
| boolean | regionMatches(boolean ignoreCase, int toffset,String other, int ooffset, int len) Tests if two string regions are equal. |
| boolean | regionMatches(int toffset,String other, int ooffset, int len) Tests if two string regions are equal. |
| String | replace(char oldChar, char newChar) Returns a new string resulting from replacing all occurrences of oldChar in this string with newChar. |
| boolean | startsWith(String prefix) Tests if this string starts with the specified prefix. |
| boolean | startsWith(String prefix, int toffset) Tests if this string starts with the specified prefix beginning a specified index. |
| String | substring(int beginIndex) Returns a new string that is a substring of this string. |
| String | substring(int beginIndex, int endIndex) Returns a new string that is a substring of this string. |
| char[] | toCharArray() Converts this string to a new character array. |
| String | toLowerCase() Converts all of the characters in this String to lower case using the rules of the default locale, which is returned by Locale.getDefault. |
| String | toLowerCase(Locale locale) Converts all of the characters in this String to lower case using the rules of the given Locale. |
| String | toString() This object (which is already a string!) is itself returned. |
| String | toUpperCase() Converts all of the characters in this String to upper case using the rules of the default locale, which is returned by Locale.getDefault. |
| String | toUpperCase(Locale locale) Converts all of the characters in this String to upper case using the rules of the given locale. |
| String | trim() Removes white space from both ends of this string. |
| static String | valueOf(boolean b) Returns the string representation of the boolean argument. |
| static String | valueOf(char c) Returns the string representation of the char argument. |
| static String | valueOf(char[] data) Returns the string representation of the char array argument. |
| static String | valueOf(char[] data, int offset, int count) Returns the string representation of a specific subarray of the char array argument. |
| static String | valueOf(double d) Returns the string representation of the double argument. |
| static String | valueOf(float f) Returns the string representation of the float argument. |
| static String | valueOf(int i) Returns the string representation of the int argument. |
| static String | valueOf(long l) Returns the string representation of the long argument. |
| static String | valueOf(Object obj) Returns the string representation of the Object argument. |
| *Methods inherited from class java.lang.*Object |
| clone,finalize,getClass,notify,notifyAll,wait,wait,wait |
| Field Detail |
CASE_INSENSITIVE_ORDER
public static final Comparator CASE_INSENSITIVE_ORDERReturns a Comparator that ordersStringobjects as bycompareToIgnoreCase. This comparator is serializable.Note that this Comparator doesnottake locale into account, and will result in an unsatisfactory ordering for certain locales. The java.text package providesCollatorsto allow locale-sensitive ordering.See Also:Collator.compare(String, String)Since:1.2| Constructor Detail |
String
public String()Initializes a newly createdStringobject so that it represents an empty character sequence.
String
public String(String original)Initializes a newly createdStringobject so that it represents the same sequence of characters as the argument; in other words, the newly created string is a copy of the argument string.Parameters:value- aString.
String
public String(char[] value)Allocates a newStringso that it represents the sequence of characters currently contained in the character array argument. The contents of the character array are copied; subsequent modification of the character array does not affect the newly created string.Parameters:value- the initial value of the string.Throws:[NullPointerException]- ifvalueisnull.
String
public String(char[] value,
int offset,
int count)Allocates a newStringthat contains characters from a subarray of the character array argument. Theoffsetargument is the index of the first character of the subarray and thecountargument specifies the length of the subarray. The contents of the subarray are copied; subsequent modification of the character array does not affect the newly created string.Parameters:value- array that is the source of characters.offset- the initial offset.count- the length.Throws:[IndexOutOfBoundsException]- if theoffsetandcountarguments index characters outside the bounds of thevaluearray.[NullPointerException]- ifvalueisnull.
String
public String(byte[] ascii,
int hibyte,
int offset,
int count)Deprecated. This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via theStringconstructors that take a character-encoding name or that use the platform's default encoding. Allocates a newStringconstructed from a subarray of an array of 8-bit integer values.Theoffsetargument is the index of the first byte of the subarray, and thecountargument specifies the length of the subarray.Eachbytein the subarray is converted to acharas specified in the method above.Parameters:ascii- the bytes to be converted to characters.hibyte- the top 8 bits of each 16-bit Unicode character.offset- the initial offset.count- the length.Throws:[IndexOutOfBoundsException]- if theoffsetorcountargument is invalid.[NullPointerException]- ifasciiisnull.See Also:String(byte[], int),String(byte[], int, int, java.lang.String),String(byte[], int, int),String(byte[], java.lang.String),String(byte[])
String
public String(byte[] ascii,
int hibyte)Deprecated. This method does not properly convert bytes into characters. As of JDK 1.1, the preferred way to do this is via theStringconstructors that take a character-encoding name or that use the platform's default encoding. Allocates a newStringcontaining characters constructed from an array of 8-bit integer values. Each charactercin the resulting string is constructed from the corresponding componentbin the byte array such that:c== (char)(((hibyte & 0xff) << 8) | (b& 0xff))Parameters:ascii- the bytes to be converted to characters.hibyte- the top 8 bits of each 16-bit Unicode character.Throws:[NullPointerException]- Ifasciiisnull.See Also:String(byte[], int, int, java.lang.String),String(byte[], int, int),String(byte[], java.lang.String),String(byte[])
String
public String(byte[] bytes,
int offset,
int length,
String enc)
throws [UnsupportedEncodingExceptionConstruct] a newStringby converting the specified subarray of bytes using the specified character encoding. The length of the newStringis a function of the encoding, and hence may not be equal to the length of the subarray.Parameters:bytes- The bytes to be converted into charactersoffset- Index of the first byte to convertlength- Number of bytes to convertenc- The name of a supportedcharacter encodingThrows:[UnsupportedEncodingException]- if the named encoding is not supportedIndexOutOfBoundsException- if theoffsetandcountarguments index characters outside the bounds of thevaluearray.Since:JDK1.1
String
public String(byte[] bytes,
String enc)
throws [UnsupportedEncodingExceptionConstruct] a newStringby converting the specified array of bytes using the specified character encoding. The length of the newStringis a function of the encoding, and hence may not be equal to the length of the byte array.Parameters:bytes- The bytes to be converted into charactersenc- The name of a supportedcharacter encodingThrows:[UnsupportedEncodingException]- If the named encoding is not supportedSince:JDK1.1
String
public String(byte[] bytes,
int offset,
int length)Construct a newStringby converting the specified subarray of bytes using the platform's default character encoding. The length of the newStringis a function of the encoding, and hence may not be equal to the length of the subarray.Parameters:bytes- The bytes to be converted into charactersoffset- Index of the first byte to convertlength- Number of bytes to convertSince:JDK1.1
String
public String(byte[] bytes)Construct a newStringby converting the specified array of bytes using the platform's default character encoding. The length of the newStringis a function of the encoding, and hence may not be equal to the length of the byte array.Parameters:bytes- The bytes to be converted into charactersSince:JDK1.1
String
public String([StringBuffer] buffer)Allocates a new string that contains the sequence of characters currently contained in the string buffer argument. The contents of the string buffer are copied; subsequent modification of the string buffer does not affect the newly created string.Parameters:buffer- aStringBuffer.Throws:[NullPointerException]- Ifbufferisnull.| Method Detail |
length
public int length()Returns the length of this string. The length is equal to the number of 16-bit Unicode characters in the string.Returns:the length of the sequence of characters represented by this object.
charAt
public char charAt(int index)Returns the character at the specified index. An index ranges from0tolength() - 1. The first character of the sequence is at index0, the next at index1, and so on, as for array indexing.Parameters:index- the index of the character.Returns:the character at the specified index of this string. The first character is at index0.Throws:[IndexOutOfBoundsException]- if theindexargument is negative or not less than the length of this string.
getChars
public void getChars(int srcBegin,
int srcEnd,
char[] dst,
int dstBegin)Copies characters from this string into the destination character array.The first character to be copied is at indexsrcBegin; the last character to be copied is at indexsrcEnd-1(thus the total number of characters to be copied issrcEnd-srcBegin). The characters are copied into the subarray ofdststarting at indexdstBeginand ending at index:dstbegin + (srcEnd-srcBegin) - 1Parameters:srcBegin- index of the first character in the string to copy.srcEnd- index after the last character in the string to copy.dst- the destination array.dstBegin- the start offset in the destination array.Throws:[IndexOutOfBoundsException]- If any of the following is true:srcBeginis negative.srcBeginis greater thansrcEndsrcEndis greater than the length of this stringdstBeginis negativedstBegin+(srcEnd-srcBegin)is larger thandst.lengthNullPointerException- ifdstisnull
getBytes
public void getBytes(int srcBegin,
int srcEnd,
byte[] dst,
int dstBegin)Deprecated. This method does not properly convert characters into bytes. As of JDK 1.1, the preferred way to do this is via thegetBytes(String enc)method, which takes a character-encoding name, or thegetBytes()method, which uses the platform's default encoding. Copies characters from this string into the destination byte array. Each byte receives the 8 low-order bits of the corresponding character. The eight high-order bits of each character are not copied and do not participate in the transfer in any way.The first character to be copied is at indexsrcBegin; the last character to be copied is at indexsrcEnd-1. The total number of characters to be copied issrcEnd-srcBegin. The characters, converted to bytes, are copied into the subarray ofdststarting at indexdstBeginand ending at index:dstbegin + (srcEnd-srcBegin) - 1Parameters:srcBegin- index of the first character in the string to copy.srcEnd- index after the last character in the string to copy.dst- the destination array.dstBegin- the start offset in the destination array.Throws:[IndexOutOfBoundsException]- if any of the following is true:srcBeginis negativesrcBeginis greater thansrcEndsrcEndis greater than the length of this [StringdstBeginis] negativedstBegin+(srcEnd-srcBegin)is larger thandst.lengthNullPointerException- ifdstisnull
getBytes
public byte[] getBytes(String enc)
throws [UnsupportedEncodingExceptionConvert] thisStringinto bytes according to the specified character encoding, storing the result into a new byte array.Parameters:enc- The name of a supportedcharacter encodingReturns:The resultant byte arrayThrows:[UnsupportedEncodingException]- If the named encoding is not supportedSince:JDK1.1
getBytes
public byte[] getBytes()Convert thisStringinto bytes according to the platform's default character encoding, storing the result into a new byte array.Returns:the resultant byte array.Since:JDK1.1
equals
public boolean equals(Object anObject)Compares this string to the specified object. The result istrueif and only if the argument is notnulland is aStringobject that represents the same sequence of characters as this object.Overrides:equalsin classObjectParameters:anObject- the object to compare thisStringagainst.Returns:trueif theStringare equal;falseotherwise.See Also:compareTo(java.lang.String),equalsIgnoreCase(java.lang.String)
equalsIgnoreCase
public boolean equalsIgnoreCase(String anotherString)Compares thisStringto anotherString, ignoring case considerations. Two strings are considered equal ignoring case if they are of the same length, and corresponding characters in the two strings are equal ignoring case.Two charactersc1andc2are considered the same, ignoring case if at least one of the following is true:The two characters are the same (as compared by the==operator).Applying the methodCharacter.toUpperCase(char)to each character produces the same result.Applying the methodCharacter.toLowerCase(char)to each character produces the same result.Parameters:anotherString- theStringto compare thisStringagainst.Returns:trueif the argument is notnulland theStrings are equal, ignoring case;falseotherwise.See Also:equals(Object),Character.toLowerCase(char),Character.toUpperCase(char)
compareTo
public int compareTo(String anotherString)Compares two strings lexicographically. The comparison is based on the Unicode value of each character in the strings. The character sequence represented by thisStringobject is compared lexicographically to the character sequence represented by the argument string. The result is a negative integer if thisStringobject lexicographically precedes the argument string. The result is a positive integer if thisStringobject lexicographically follows the argument string. The result is zero if the strings are equal;compareToreturns0exactly when theequals(Object)method would returntrue.This is the definition of lexicographic ordering. If two strings are different, then either they have different characters at some index that is a valid index for both strings, or their lengths are different, or both. If they have different characters at one or more index positions, letkbe the smallest such index; then the string whose character at positionkhas the smaller value, as determined by using the < operator, lexicographically precedes the other string. In this case,compareToreturns the difference of the two character values at positionkin the two string – that is, the value:this.charAt(k)anotherString.charAt(k)If there is no index position at which they differ, then the shorter string lexicographically precedes the longer string. In this case,compareToreturns the difference of the lengths of the strings – that is, the value:this.length()-anotherString.length()Parameters:anotherString theStringto be compared.Returns:the value0if the argument string is equal to this string; a value less than0if this string is lexicographically less than the string argument; and a value greater than0if this string is lexicographically greater than the string argument.Throws:[NullPointerException]- ifanotherStringisnull.
compareTo
public int compareTo(Object o)Compares this String to another Object. If the Object is a String, this function behaves likecompareTo(String). Otherwise, it throws aClassCastException(as Strings are comparable only to other Strings).Specified by:compareToin interfaceComparableParameters:o- theObjectto be compared.Returns:the value0if the argument is a string lexicographically equal to this string; a value less than0if the argument is a string lexicographically greater than this string; and a value greater than0if the argument is a string lexicographically less than this string.Throws:[ClassCastException]- if the argument is not aString.Since:1.2See Also:Comparable
compareToIgnoreCase
public int compareToIgnoreCase(String str)Compares two strings lexicographically, ignoring case considerations. This method returns an integer whose sign is that ofthis.toUpperCase().toLowerCase().compareTo( str.toUpperCase().toLowerCase()).Note that this method doesnottake locale into account, and will result in an unsatisfactory ordering for certain locales. The java.text package providescollatorsto allow locale-sensitive ordering.Parameters:str- theStringto be compared.Returns:a negative integer, zero, or a positive integer as the the specified String is greater than, equal to, or less than this String, ignoring case considerations.Since:1.2See Also:Collator.compare(String, String)
regionMatches
public boolean regionMatches(int toffset,
String other,
int ooffset,
int len)Tests if two string regions are equal.A substring of thisStringobject is compared to a substring of the argument other. The result is true if these substrings represent identical character sequences. The substring of thisStringobject to be compared begins at indextoffsetand has lengthlen. The substring of other to be compared begins at indexooffsetand has lengthlen. The result isfalseif and only if at least one of the following is true:toffsetis negative.ooffsetis negative.toffset+lenis greater than the length of thisStringobject.ooffset+lenis greater than the length of the other argument.There is some nonnegative integerkless thanlensuch that:this.charAt(toffset+k) != other.charAt(ooffset+k)Parameters:toffset- the starting offset of the subregion in this string.other- the string argument.ooffset- the starting offset of the subregion in the string argument.len- the number of characters to compare.Returns:trueif the specified subregion of this string exactly matches the specified subregion of the string argument;falseotherwise.Throws:[NullPointerException]- ifotherisnull.
regionMatches
public boolean regionMatches(boolean ignoreCase,
int toffset,
String other,
int ooffset,
int len)Tests if two string regions are equal.A substring of thisStringobject is compared to a substring of the argumentother. The result istrueif these substrings represent character sequences that are the same, ignoring case if and only ifignoreCaseis true. The substring of thisStringobject to be compared begins at indextoffsetand has lengthlen. The substring ofotherto be compared begins at indexooffsetand has lengthlen. The result isfalseif and only if at least one of the following is true:toffsetis negative.ooffsetis negative.toffset+lenis greater than the length of thisStringobject.ooffset+lenis greater than the length of the other argument.There is some nonnegative integerkless thanlensuch that:this.charAt(toffset+k) != other.charAt(ooffset+k)ignoreCaseistrueand there is some nonnegative integerkless thanlensuch that:Character.toLowerCase(this.charAt(toffset+k)) != Character.toLowerCase(other.charAt(ooffset+k))and:Character.toUpperCase(this.charAt(toffset+k)) != Character.toUpperCase(other.charAt(ooffset+k))Parameters:ignoreCase- iftrue, ignore case when comparing characters.toffset- the starting offset of the subregion in this string.other- the string argument.ooffset- the starting offset of the subregion in the string argument.len- the number of characters to compare.Returns:trueif the specified subregion of this string matches the specified subregion of the string argument;falseotherwise. Whether the matching is exact or case insensitive depends on theignoreCaseargument.
startsWith
public boolean startsWith(String prefix,
int toffset)Tests if this string starts with the specified prefix beginning a specified index.Parameters:prefix- the prefix.toffset- where to begin looking in the string.Returns:trueif the character sequence represented by the argument is a prefix of the substring of this object starting at indextoffset;falseotherwise. The result isfalseiftoffsetis negative or greater than the length of thisStringobject; otherwise the result is the same as the result of the expressionthis.subString(toffset).startsWith(prefix)Throws:[NullPointerException]- ifprefixisnull.
startsWith
public boolean startsWith(String prefix)Tests if this string starts with the specified prefix.Parameters:prefix- the prefix.Returns:trueif the character sequence represented by the argument is a prefix of the character sequence represented by this string;falseotherwise. Note also thattruewill be returned if the argument is an empty string or is equal to thisStringobject as determined by theequals(Object)method.Throws:[NullPointerException]- ifprefixisnull.Since:JDK1. 0
endsWith
public boolean endsWith(String suffix)Tests if this string ends with the specified suffix.Parameters:suffix- the suffix.Returns:trueif the character sequence represented by the argument is a suffix of the character sequence represented by this object;falseotherwise. Note that the result will betrueif the argument is the empty string or is equal to thisStringobject as determined by theequals(Object)method.Throws:[NullPointerException]- ifsuffixisnull.
hashCode
public int hashCode()Returns a hashcode for this string. The hashcode for aStringobject is computed ass[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]usingintarithmetic, wheres[i]is theith character of the string,nis the length of the string, and^indicates exponentiation. (The hash value of the empty string is zero.)Overrides:hashCodein classObjectReturns:a hash code value for this object.
indexOf
public int indexOf(int ch)Returns the index within this string of the first occurrence of the specified character. If a character with valuechoccurs in the character sequence represented by thisStringobject, then the index of the first such occurrence is returned – that is, the smallest valueksuch that:this.charAt(k) == chistrue. If no such character occurs in this string, then-1is returned.Parameters:ch- a character.Returns:the index of the first occurrence of the character in the character sequence represented by this object, or-1if the character does not occur.
indexOf
public int indexOf(int ch,
int fromIndex)Returns the index within this string of the first occurrence of the specified character, starting the search at the specified index.If a character with valuechoccurs in the character sequence represented by thisStringobject at an index no smaller thanfromIndex, then the index of the first such occurrence is returned-that is, the smallest valueksuch that:(this.charAt(k) == ch) && (k>= fromIndex)is true. If no such character occurs in this string at or after positionfromIndex, then-1is returned.There is no restriction on the value offromIndex. If it is negative, it has the same effect as if it were zero: this entire string may be searched. If it is greater than the length of this string, it has the same effect as if it were equal to the length of this string:-1is returned.Parameters:ch a character.fromIndex- the index to start the search from.Returns:the index of the first occurrence of the character in the character sequence represented by this object that is greater than or equal tofromIndex, or-1if the character does not occur.
lastIndexOf
public int lastIndexOf(int ch)Returns the index within this string of the last occurrence of the specified character. That is, the index returned is the largest valueksuch that:this.charAt(k) == chis true. The String is searched backwards starting at the last character.Parameters:ch- a character.Returns:the index of the last occurrence of the character in the character sequence represented by this object, or-1if the character does not occur.
lastIndexOf
public int lastIndexOf(int ch,
int fromIndex)Returns the index within this string of the last occurrence of the specified character, searching backward starting at the specified index. That is, the index returned is the largest valueksuch that:this.charAt(k) == ch) && (k <= fromIndex)is true.Parameters:ch- a character.fromIndex- the index to start the search from. There is no restriction on the value offromIndex. If it is greater than or equal to the length of this string, it has the same effect as if it were equal to one less than the length of this string: this entire string may be searched. If it is negative, it has the same effect as if it were -1: -1 is returned.Returns:the index of the last occurrence of the character in the character sequence represented by this object that is less than or equal tofromIndex, or-1if the character does not occur before that point.
indexOf
public int indexOf(String str)Returns the index within this string of the first occurrence of the specified substring. The integer returned is the smallest valueksuch that:this.startsWith(str,k)istrue.Parameters:str- any string.Returns:if the string argument occurs as a substring within this object, then the index of the first character of the first such substring is returned; if it does not occur as a substring,1is returned.Throws:[NullPointerException] ifstrisnull.
indexOf
public int indexOf(String str,
int fromIndex)Returns the index within this string of the first occurrence of the specified substring, starting at the specified index. The integer returned is the smallest valueksuch that:this.startsWith(str,k) && (k>= fromIndex)istrue.There is no restriction on the value offromIndex. If it is negative, it has the same effect as if it were zero: this entire string may be searched. If it is greater than the length of this string, it has the same effect as if it were equal to the length of this string:1is returned.Parameters:str the substring to search for.fromIndex- the index to start the search from.Returns:If the string argument occurs as a substring within this object at a starting index no smaller thanfromIndex, then the index of the first character of the first such substring is returned. If it does not occur as a substring starting atfromIndexor beyond,1is returned.Throws:[NullPointerException] ifstrisnull
lastIndexOf
public int lastIndexOf(String str)Returns the index within this string of the rightmost occurrence of the specified substring. The rightmost empty string "" is considered to occur at the index valuethis.length(). The returned index is the largest valueksuch thatthis.startsWith(str, k)is true.Parameters:str- the substring to search for.Returns:if the string argument occurs one or more times as a substring within this object, then the index of the first character of the last such substring is returned. If it does not occur as a substring,1is returned.Throws:[NullPointerException] ifstrisnull.
lastIndexOf
public int lastIndexOf(String str,
int fromIndex)Returns the index within this string of the last occurrence of the specified substring. The returned index indicates the start of the substring, and it must be equal to or less thanfromIndex. That is, the index returned is the largest valueksuch that:this.startsWith(str, k) && (k <= fromIndex)Parameters:str- the substring to search for.fromIndex- the index to start the search from. There is no restriction on the value of fromIndex. If it is greater than the length of this string, it has the same effect as if it were equal to the length of this string: this entire string may be searched. If it is negative, it has the same effect as if it were 1: -1 is returned.Returns:If the string argument occurs one or more times as a substring within this object at a starting index no greater thanfromIndex, then the index of the first character of the last such substring is returned. If it does not occur as a substring starting atfromIndexor earlier,-1is returned.Throws:[NullPointerException] ifstrisnull.
substring
public String substring(int beginIndex)Returns a new string that is a substring of this string. The substring begins with the character at the specified index and extends to the end of this string.Examples:"unhappy".substring(2) returns "happy" "Harbison".substring(3) returns "bison" "emptiness".substring(9) returns "" (an empty string)Parameters:beginIndex- the beginning index, inclusive.Returns:the specified substring.Throws:[IndexOutOfBoundsException]- ifbeginIndexis negative or larger than the length of thisStringobject.
substring
public String substring(int beginIndex,
int endIndex)Returns a new string that is a substring of this string. The substring begins at the specifiedbeginIndexand extends to the character at indexendIndex - 1. Thus the length of the substring isendIndex-beginIndex.Examples:"hamburger".substring(4, 8) returns "urge" "smiles".substring(1, 5) returns "mile"Parameters:beginIndex- the beginning index, inclusive.endIndex- the ending index, exclusive.Returns:the specified substring.Throws:[IndexOutOfBoundsException]- if thebeginIndexis negative, orendIndexis larger than the length of thisStringobject, orbeginIndexis larger thanendIndex.
concat
public String concat(String str)Concatenates the specified string to the end of this string.If the length of the argument string is0, then thisStringobject is returned. Otherwise, a newStringobject is created, representing a character sequence that is the concatenation of the character sequence represented by thisStringobject and the character sequence represented by the argument string.Examples:"cares".concat("s") returns "caress" "to".concat("get").concat("her") returns "together"Parameters:str- theStringthat is concatenated to the end of thisString.Returns:a string that represents the concatenation of this object's characters followed by the string argument's characters.Throws:[NullPointerException]- ifstrisnull.
replace
public String replace(char oldChar,
char newChar)Returns a new string resulting from replacing all occurrences ofoldCharin this string withnewChar.If the characteroldChardoes not occur in the character sequence represented by thisStringobject, then a reference to thisStringobject is returned. Otherwise, a newStringobject is created that represents a character sequence identical to the character sequence represented by thisStringobject, except that every occurrence ofoldCharis replaced by an occurrence ofnewChar.Examples:"mesquite in your cellar".replace('e', 'o') returns "mosquito in your collar" "the war of baronets".replace('r', 'y') returns "the way of bayonets" "sparring with a purple porpoise".replace('p', 't') returns "starring with a turtle tortoise" "JonL".replace('q', 'x') returns "JonL" (no change)Parameters:oldChar- the old character.newChar- the new character.Returns:a string derived from this string by replacing every occurrence ofoldCharwithnewChar.
toLowerCase
public String toLowerCase(Locale locale)Converts all of the characters in thisStringto lower case using the rules of the givenLocale. Usually, the characters are converted by callingCharacter.toLowerCase. Exceptions to this rule are listed in the following table: Language Code of [LocaleUpper] [CaseLower] [CaseDescriptiontr] (Turkish)\u0130\u0069capital letter I with dot above > small letter itr (Turkish)\u0049\u0131capital letter I -> small letter dotless iParameters:locale use the case transformation rules for this localeReturns:the String, converted to lowercase.Since:JDK1.1See Also:Character.toLowerCase(char),toUpperCase(Locale)
toLowerCase
public String toLowerCase()Converts all of the characters in thisStringto lower case using the rules of the default locale, which is returned byLocale.getDefault.If no character in the string has a different lowercase version, based on calling thetoLowerCasemethod defined byCharacter, then the original string is returned.Otherwise, this method creates a newStringobject that represents a character sequence identical in length to the character sequence represented by this String object, with every character equal to the result of applying the methodCharacter.toLowerCaseto the corresponding character of thisStringobject.Examples:"French Fries".toLowerCase() returns "french fries" "".toLowerCase() returns ""Returns:the string, converted to lowercase.See Also:Character.toLowerCase(char),toLowerCase(Locale)
toUpperCase
public String toUpperCase(Locale locale)Converts all of the characters in thisStringto upper case using the rules of the given locale. Usually, the characters are converted by callingCharacter.toUpperCase. Exceptions to this rule are listed in the following table: Language Code of [LocaleLower] [CaseUpper] [CaseDescriptiontr] (Turkish)\u0069\u0130small letter i > capital letter I with dot abovetr (Turkish)\u0131\u0049small letter dotless i -> capital letter I(all)\u00df\u0053 \u0053small letter sharp s -> two letters: SSParameters:locale use the case transformation rules for this localeReturns:the String, converted to uppercase.Since:JDK1.1See Also:Character.toUpperCase(char),toLowerCase(Locale)
toUpperCase
public String toUpperCase()Converts all of the characters in thisStringto upper case using the rules of the default locale, which is returned byLocale.getDefault.If no character in this string has a different uppercase version, based on calling thetoUpperCasemethod defined byCharacter, then the original string is returned.Otherwise, this method creates a newStringobject representing a character sequence identical in length to the character sequence represented by thisStringobject and with every character equal to the result of applying the methodCharacter.toUpperCaseto the corresponding character of thisStringobject.Examples:"Fahrvergnügen".toUpperCase() returns "FAHRVERGNÜGEN" "Visit Ljubinje!".toUpperCase() returns "VISIT LJUBINJE!"Returns:the string, converted to uppercase.See Also:Character.toUpperCase(char),toUpperCase(Locale)
trim
public String trim()Removes white space from both ends of this string.If thisStringobject represents an empty character sequence, or the first and last characters of character sequence represented by thisStringobject both have codes greater than'\u0020'(the space character), then a reference to thisStringobject is returned.Otherwise, if there is no character with a code greater than'\u0020'in the string, then a newStringobject representing an empty string is created and returned.Otherwise, letkbe the index of the first character in the string whose code is greater than'\u0020', and letmbe the index of the last character in the string whose code is greater than'\u0020'. A newStringobject is created, representing the substring of this string that begins with the character at indexkand ends with the character at indexm-that is, the result ofthis.substring(k, m+1).This method may be used to trimwhitespacefrom the beginning and end of a string; in fact, it trims all ASCII control characters as well.Returns:this string, with white space removed from the front and end.
toString
public String toString()This object (which is already a string!) is itself returned.Overrides:toStringin classObjectReturns:the string itself.
toCharArray
public char[] toCharArray()Converts this string to a new character array.Returns:a newly allocated character array whose length is the length of this string and whose contents are initialized to contain the character sequence represented by this string.
valueOf
public static String valueOf(Object obj)Returns the string representation of theObjectargument.Parameters:obj- anObject.Returns:if the argument isnull, then a string equal to"null"; otherwise, the value ofobj.toString()is returned.See Also:Object.toString()
valueOf
public static String valueOf(char[] data)Returns the string representation of thechararray argument. The contents of the character array are copied; subsequent modification of the character array does not affect the newly created string.Parameters:data- achararray.Returns:a newly allocated string representing the same sequence of characters contained in the character array argument.
valueOf
public static String valueOf(char[] data,
int offset,
int count)Returns the string representation of a specific subarray of thechararray argument.Theoffsetargument is the index of the first character of the subarray. Thecountargument specifies the length of the subarray. The contents of the subarray are copied; subsequent modification of the character array does not affect the newly created string.Parameters:data- the character array.offset- the initial offset into the value of theString.count- the length of the value of theString.Returns:a newly allocated string representing the sequence of characters contained in the subarray of the character array argument.Throws:[NullPointerException]- ifdataisnull.[IndexOutOfBoundsException]- ifoffsetis negative, orcountis negative, oroffset+countis larger thandata.length.
copyValueOf
public static String copyValueOf(char[] data,
int offset,
int count)Returns a String that is equivalent to the specified character array. It creates a new array and copies the characters into it.Parameters:data- the character array.offset- initial offset of the subarray.count- length of the subarray.Returns:aStringthat contains the characters of the specified subarray of the character array.
copyValueOf
public static String copyValueOf(char[] data)Returns a String that is equivalent to the specified character array. It creates a new array and copies the characters into it.Parameters:data- the character array.Returns:aStringthat contains the characters of the character array.
valueOf
public static String valueOf(boolean b)Returns the string representation of thebooleanargument.Parameters:b- aboolean.Returns:if the argument istrue, a string equal to"true"is returned; otherwise, a string equal to"false"is returned.
valueOf
public static String valueOf(char c)Returns the string representation of thecharargument.Parameters:c- achar.Returns:a newly allocated string of length1containing as its single character the argumentc.
valueOf
public static String valueOf(int i)Returns the string representation of theintargument.The representation is exactly the one returned by theInteger.toStringmethod of one argument.Parameters:i- anint.Returns:a newly allocated string containing a string representation of theintargument.See Also:Integer.toString(int, int)
valueOf
public static String valueOf(long l)Returns the string representation of thelongargument.The representation is exactly the one returned by theLong.toStringmethod of one argument.Parameters:l- along.Returns:a newly allocated string containing a string representation of thelongargument.See Also:Long.toString(long)
valueOf
public static String valueOf(float f)Returns the string representation of thefloatargument.The representation is exactly the one returned by theFloat.toStringmethod of one argument.Parameters:f- afloat.Returns:a newly allocated string containing a string representation of thefloatargument.See Also:Float.toString(float)
valueOf
public static String valueOf(double d)Returns the string representation of thedoubleargument.The representation is exactly the one returned by theDouble.toStringmethod of one argument.Parameters:d- adouble.Returns:a newly allocated string containing a string representation of thedoubleargument.See Also:Double.toString(double)
intern
public String intern()Returns a canonical representation for the string object.A pool of strings, initially empty, is maintained privately by the classString.When the intern method is invoked, if the pool already contains a string equal to thisStringobject as determined by theequals(Object)method, then the string from the pool is returned. Otherwise, thisStringobject is added to the pool and a reference to thisStringobject is returned.It follows that for any two stringssandt,s.intern() == t.intern()istrueif and only ifs.equals(t)istrue.All literal strings and string-valued constant expressions are interned. String literals are defined in §3.10.5 of theJava Language [SpecificationReturns]:a string that has the same contents as this string, but is guaranteed to be from a pool of unique strings.
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