difference among String,StringBuilder,StringBuffer,
difference among String,StringBuilder,StringBuffer
String常用构造函数
1 String(byte[] bytes)
2
3 String(byte[] bytes, int offset, int length)
4
5 String(char[] value)
6
7 String(char[] value, int offset, int count)
8
9 String(int[] codePoints, int offset, int count)
10
11 String(String original)
12
13 String(StringBuffer buffer)
14
15 String(StringBuilder builder)
Modifier and Type | Method and Description |
---|---|
char |
charAt(int index) Returns the char value at the specified index. |
int |
codePointAt(int index) Returns the character (Unicode code point) at the specified index. |
int |
codePointBefore(int index) Returns the character (Unicode code point) before the specified index. |
int |
codePointCount(int beginIndex, int endIndex) Returns the number of Unicode code points in the specified text range of this String . |
int |
compareTo(String anotherString) Compares two strings lexicographically. |
int |
compareToIgnoreCase(String str) Compares two strings lexicographically, ignoring case differences. |
String |
concat(String str) Concatenates the specified string to the end of this string. |
boolean |
contains(CharSequence s) Returns true if and only if this string contains the specified sequence of char values. |
boolean |
contentEquals(CharSequence cs) Compares this string to the specified CharSequence . |
boolean |
contentEquals(StringBuffer sb) Compares this string to the specified StringBuffer . |
static String |
copyValueOf(char[] data) Equivalent to valueOf(char[]) . |
static String |
copyValueOf(char[] data, int offset, int count) Equivalent to valueOf(char[], int, int) . |
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. |
static String |
format(Locale l, String format, Object... args) Returns a formatted string using the specified locale, format string, and arguments. |
static String |
format(String format, Object... args) Returns a formatted string using the specified format string and arguments. |
byte[] |
getBytes() Encodes this String into a sequence of bytes using the platform's default charset, storing the result into a new byte array. |
byte[] |
getBytes(Charset charset) Encodes this String into a sequence of bytes using the given charset, storing the result into a new byte array. |
|
|
byte[] |
getBytes(String charsetName) Encodes this String into a sequence of bytes using the named charset, 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 hash code 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. |
boolean |
isEmpty() Returns true if, and only if, length() is 0 . |
static String |
join(CharSequence delimiter, CharSequence... elements) Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter . |
static String |
join(CharSequence delimiter, Iterable<? extends CharSequence> elements) Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter . |
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 last 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, searching backward starting at the specified index. |
int |
length() Returns the length of this string. |
boolean |
matches(String regex) Tells whether or not this string matches the given regular expression. |
int |
offsetByCodePoints(int index, int codePointOffset) Returns the index within this String that is offset from the given index by codePointOffset code points. |
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 string resulting from replacing all occurrences of oldChar in this string with newChar . |
String |
replace(CharSequence target, CharSequence replacement) Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence. |
String |
replaceAll(String regex, String replacement) Replaces each substring of this string that matches the given regular expression with the given replacement. |
String |
replaceFirst(String regex, String replacement) Replaces the first substring of this string that matches the given regular expression with the given replacement. |
String[] |
split(String regex) Splits this string around matches of the given regular expression. |
String[] |
split(String regex, int limit) Splits this string around matches of the given regular expression. |
boolean |
startsWith(String prefix) Tests if this string starts with the specified prefix. |
boolean |
startsWith(String prefix, int toffset) Tests if the substring of this string beginning at the specified index starts with the specified prefix. |
CharSequence |
subSequence(int beginIndex, int endIndex) Returns a character sequence that is a subsequence of this sequence. |
String |
substring(int beginIndex) Returns a string that is a substring of this string. |
String |
substring(int beginIndex, int endIndex) Returns a 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. |
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. |
String |
toUpperCase(Locale locale) Converts all of the characters in this String to upper case using the rules of the given Locale . |
String |
trim() Returns a string whose value is this string, with any leading and trailing whitespace removed. |
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. |
StringBuffer和StringBuilder的对象是变量,所以效能要比String要高,java设想机无需回收。
序号 | 方法描述 |
---|---|
1 | public StringBuffer append(String s) 将指定的字符串追加到此字符序列。 |
2 | public StringBuffer reverse() 将此字符序列用其反转形式取代。 |
3 | public delete(int start, int end) 移除此序列的子字符串中的字符。 |
4 | public insert(int offset, int i) 将 int 参数的字符串表示形式插入此序列中。 |
5 | replace(int start, int end, String str) 使用给定 String 中的字符替换此序列的子字符串中的字符。 |
序号 | 方法描述 |
---|---|
1 | int capacity() 返回当前容量。 |
2 | char charAt(int index) 返回此序列中指定索引处的 char 值。 |
3 | void ensureCapacity(int minimumCapacity) 确保容量至少等于指定的最小值。 |
4 | void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) 将字符从此序列复制到目标字符数组 dst 。 |
5 | int indexOf(String str) 返回第一次出现的指定子字符串在该字符串中的索引。 |
6 | int indexOf(String str, int fromIndex) 从指定的索引处开始,返回第一次出现的指定子字符串在该字符串中的索引。 |
7 | int lastIndexOf(String str) 返回最右边出现的指定子字符串在此字符串中的索引。 |
8 | int lastIndexOf(String str, int fromIndex) 返回最后一次出现的指定子字符串在此字符串中的索引。 |
9 | int length() 返回长度(字符数)。 |
10 | void setCharAt(int index, char ch) 将给定索引处的字符设置为 ch 。 |
11 | void setLength(int newLength) 设置字符序列的长度。 |
12 | CharSequence subSequence(int start, int end) 返回一个新的字符序列,该字符序列是此序列的子序列。 |
13 | String substring(int start) 返回一个新的 String ,它包含此字符序列当前所包含的字符子序列。 |
14 | String substring(int start, int end) 返回一个新的 String ,它包含此序列当前所包含的字符子序列。 |
15 | String toString() 返回此序列中数据的字符串表示形式。 |
public StringBuffer deleteCharAt(int index)
public void trimToSize()
among String,StringBuilder,StringBuffer, difference among String,StringBuilder,StringBuffer String常用构造函数 1 String( byte [] bytes) 2 3 String( byte [] bytes...
difference among String,StringBuilder,StringBuffer
String常用构造函数
1 String(byte[] bytes)
2
3 String(byte[] bytes, int offset, int length)
4
5 String(char[] value)
6
7 String(char[] value, int offset, int count)
8
9 String(int[] codePoints, int offset, int count)
10
11 String(String original)
12
13 String(StringBuffer buffer)
14
15 String(StringBuilder builder)
Modifier and Type | Method and Description |
---|---|
char |
charAt(int index)
Returns the char value at the specified index.
|
int |
codePointAt(int index)
Returns the character (Unicode code point) at the specified index.
|
int |
codePointBefore(int index)
Returns the character (Unicode code point) before the specified index.
|
int |
codePointCount(int beginIndex, int endIndex)
Returns the number of Unicode code points in the specified text range of this String .
|
int |
compareTo(String anotherString)
Compares two strings lexicographically.
|
int |
compareToIgnoreCase(String str)
Compares two strings lexicographically, ignoring case differences.
|
String |
concat(String str)
Concatenates the specified string to the end of this string.
|
boolean |
contains(CharSequence s)
Returns true if and only if this string contains the specified sequence of char values.
|
boolean |
contentEquals(CharSequence cs)
Compares this string to the specified CharSequence .
|
boolean |
contentEquals(StringBuffer sb)
Compares this string to the specified StringBuffer .
|
static String |
copyValueOf(char[] data)
Equivalent to valueOf(char[]) .
|
static String |
copyValueOf(char[] data, int offset, int count)
Equivalent to valueOf(char[], int, int) .
|
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.
|
static String |
format(Locale l, String format, Object... args)
Returns a formatted string using the specified locale, format string, and arguments.
|
static String |
format(String format, Object... args)
Returns a formatted string using the specified format string and arguments.
|
byte[] |
getBytes()
Encodes this String into a sequence of bytes using the platform's default charset, storing the result into a new byte array.
|
byte[] |
getBytes(Charset charset)
Encodes this String into a sequence of bytes using the given charset, storing the result into a new byte array.
|
|
|
byte[] |
getBytes(String charsetName)
Encodes this String into a sequence of bytes using the named charset, 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 hash code 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.
|
boolean |
isEmpty()
Returns true if, and only if, length() is 0 .
|
static String |
join(CharSequence delimiter, CharSequence... elements)
Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter .
|
static String |
join(CharSequence delimiter, Iterable<? extends CharSequence> elements)
Returns a new String composed of copies of the CharSequence elements joined together with a copy of the specified delimiter .
|
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 last 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, searching backward starting at the specified index.
|
int |
length()
Returns the length of this string.
|
boolean |
matches(String regex)
Tells whether or not this string matches the given regular expression.
|
int |
offsetByCodePoints(int index, int codePointOffset)
Returns the index within this String that is offset from the given index by codePointOffset code points.
|
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 string resulting from replacing all occurrences of oldChar in this string with newChar .
|
String |
replace(CharSequence target, CharSequence replacement)
Replaces each substring of this string that matches the literal target sequence with the specified literal replacement sequence.
|
String |
replaceAll(String regex, String replacement)
Replaces each substring of this string that matches the given regular expression with the given replacement.
|
String |
replaceFirst(String regex, String replacement)
Replaces the first substring of this string that matches the given regular expression with the given replacement.
|
String[] |
split(String regex)
Splits this string around matches of the given regular expression.
|
String[] |
split(String regex, int limit)
Splits this string around matches of the given regular expression.
|
boolean |
startsWith(String prefix)
Tests if this string starts with the specified prefix.
|
boolean |
startsWith(String prefix, int toffset)
Tests if the substring of this string beginning at the specified index starts with the specified prefix.
|
CharSequence |
subSequence(int beginIndex, int endIndex)
Returns a character sequence that is a subsequence of this sequence.
|
String |
substring(int beginIndex)
Returns a string that is a substring of this string.
|
String |
substring(int beginIndex, int endIndex)
Returns a 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.
|
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.
|
String |
toUpperCase(Locale locale)
Converts all of the characters in this String to upper case using the rules of the given Locale .
|
String |
trim()
Returns a string whose value is this string, with any leading and trailing whitespace removed.
|
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.
|
StringBuffer和StringBuilder的靶子是变量,所以效用要比String要高,java虚构机无需回收。
序号 | 方法描述 |
---|---|
1 | public StringBuffer append(String s) 将指定的字符串追加到此字符序列。 |
2 | public StringBuffer reverse() 将此字符序列用其反转形式取代。 |
3 | public delete(int start, int end) 移除此序列的子字符串中的字符。 |
4 | public insert(int offset, int i) 将 int 参数的字符串表示形式插入此序列中。 |
5 | replace(int start, int end, String str) 使用给定 String 中的字符替换此序列的子字符串中的字符。 |
序号 | 方法描述 |
---|---|
1 | int capacity() 返回当前容量。 |
2 | char charAt(int index) 返回此序列中指定索引处的 char 值。 |
3 | void ensureCapacity(int minimumCapacity) 确保容量至少等于指定的最小值。 |
4 | void getChars(int srcBegin, int srcEnd, char[] dst, int dstBegin) 将字符从此序列复制到目标字符数组 dst 。 |
5 | int indexOf(String str) 返回第一次出现的指定子字符串在该字符串中的索引。 |
6 | int indexOf(String str, int fromIndex) 从指定的索引处开始,返回第一次出现的指定子字符串在该字符串中的索引。 |
7 | int lastIndexOf(String str) 返回最右边出现的指定子字符串在此字符串中的索引。 |
8 | int lastIndexOf(String str, int fromIndex) 返回最后一次出现的指定子字符串在此字符串中的索引。 |
9 | int length() 返回长度(字符数)。 |
10 | void setCharAt(int index, char ch) 将给定索引处的字符设置为 ch 。 |
11 | void setLength(int newLength) 设置字符序列的长度。 |
12 | CharSequence subSequence(int start, int end) 返回一个新的字符序列,该字符序列是此序列的子序列。 |
13 | String substring(int start) 返回一个新的 String ,它包含此字符序列当前所包含的字符子序列。 |
14 | String substring(int start, int end) 返回一个新的 String ,它包含此序列当前所包含的字符子序列。 |
15 | String toString() 返回此序列中数据的字符串表示形式。 |
public StringBuffer deleteCharAt(int index)
public void trimToSize()
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