StringUtils 工具類的常用方法

StringUtils 源碼，使用的是commons-lang3-3.1包。

下載地址 http://commons.apache.org/lang/download_lang.cgi

以下是StringUtils的各項用法
1.空字符串檢查
使用函數: StringUtils.isBlank(testString)
函數介紹: 當testString爲空,長度爲零或者僅由空白字符(whitespace)組成時,返回True;否則返回False
例程:
    String test = "";
    String test2 = "\n\n\t";
    String test3 = null;
    String test4 = "Test";

    System.out.println( "test blank? " + StringUtils.isBlank( test ) );
    System.out.println( "test2 blank? " + StringUtils.isBlank( test2 ) );
    System.out.println( "test3 blank? " + StringUtils.isBlank( test3 ) );
    System.out.println( "test4 blank? " + StringUtils.isBlank( test4 ) );
輸出如下:
test blank? true
test2 blank? true
test3 blank? true
test4 blank? False
函數StringUtils.isNotBlank(testString)的功能與StringUtils.isBlank(testString)相反.

2.清除空白字符
使用函數: StringUtils.trimToNull(testString)
函數介紹:清除掉testString首尾的空白字符,如果僅testString全由空白字符
(whitespace)組成則返回null
例程:
    String test1 = "\t";
    String test2 = " A Test ";
    String test3 = null;

    System.out.println( "test1 trimToNull: " + StringUtils.trimToNull( test1 ) );
    System.out.println( "test2 trimToNull: " + StringUtils.trimToNull( test2 ) );
    System.out.println( "test3 trimToNull: " + StringUtils.trimToNull( test3 ) );

輸出如下:
test1 trimToNull: null
test2 trimToNull: A Test
test3 trimToNull: null

注意：函數StringUtils.trim(testString)與
StringUtils.trimToNull(testString)功能類似，但testString由空白字符
(whitespace)組成時返回零長度字符串。

3.取得字符串的縮寫
使用函數: StringUtils.abbreviate(testString,width)和StringUtils.abbreviate(testString,offset，width)
函數介紹:在給定的width內取得testString的縮寫,當testString的長度小於width則返回原字符串.
例程:
String test = "This is a test of the abbreviation.";
String test2 = "Test";

    System.out.println( StringUtils.abbreviate( test, 15 ) );
    System.out.println( StringUtils.abbreviate( test, 5,15 ) );
    System.out.println( StringUtils.abbreviate( test2, 10 ) );
輸出如下:
This is a te...
...is a test...
Test

4.劈分字符串
使用函數: StringUtils.split(testString,splitChars,arrayLength)
函數介紹:splitChars中可以包含一系列的字符串來劈分testString,並可以設定得
到數組的長度.注意設定長度arrayLength和劈分字符串間有抵觸關係,建議一般情況下
不要設定長度.
例程:
String input = "A b,c.d|e";
String input2 = "Pharmacy, basketball funky";

String[] array1 = StringUtils.split( input, " ,.|");
String[] array2 = StringUtils.split( input2, " ,", 2 );

System.out.println( ArrayUtils.toString( array1 ) );
System.out.println( ArrayUtils.toString( array2 ) );
輸出如下:
{A,b,c,d,e}
{Pharmacy,basketball funky}

5.查找嵌套字符串
使用函數:StringUtils.substringBetween(testString,header,tail)
函數介紹：在testString中取得header和tail之間的字符串。不存在則返回空
例程：
    String htmlContent = "ABC1234ABC4567";
    System.out.println(StringUtils.substringBetween(htmlContent, "1234", "4567"));
    System.out.println(StringUtils.substringBetween(htmlContent, "12345", "4567"));
輸出如下：
    ABC
    null

6.去除尾部換行符
使用函數:StringUtils.chomp(testString)
函數介紹:去除testString尾部的換行符
例程:
    String input = "Hello\n";
    System.out.println( StringUtils.chomp( input ));
    String input2 = "Another test\r\n";
    System.out.println( StringUtils.chomp( input2 ));
輸出如下:
    Hello
    Another test

7.重複字符串
使用函數:StringUtils.repeat(repeatString,count)
函數介紹:得到將repeatString重複count次後的字符串
例程:
    System.out.println( StringUtils.repeat( "*", 10));
    System.out.println( StringUtils.repeat( "China ", 5));
輸出如下:
    **********
    China China China China China

其他函數:StringUtils.center( testString, count,repeatString );
函數介紹:把testString插入將repeatString重複多次後的字符串中間,得到字符串
的總長爲count
例程:
System.out.println( StringUtils.center( "China", 11,"*"));
輸出如下:
***China***

8.顛倒字符串
使用函數:StringUtils.reverse(testString)
函數介紹:得到testString中字符顛倒後的字符串
例程:
System.out.println( StringUtils.reverse("ABCDE"));
輸出如下:
EDCBA

9.判斷字符串內容的類型
函數介紹:
StringUtils.isNumeric( testString ) :如果testString全由數字組成返回True
StringUtils.isAlpha( testString ) :如果testString全由字母組成返回True
StringUtils.isAlphanumeric( testString ) :如果testString全由數字或數字組
成返回True
StringUtils.isAlphaspace( testString ) :如果testString全由字母或空格組
成返回True

例程:
    String state = "Virginia";
    System.out.println( "Is state number? " + StringUtils.isNumeric(
state ) );
    System.out.println( "Is state alpha? " + StringUtils.isAlpha( state )
);
    System.out.println( "Is state alphanumeric? " +StringUtils.isAlphanumeric( state ) );
    System.out.println( "Is state alphaspace? " + StringUtils.isAlphaSpace( state ) );
輸出如下:
    Is state number? false
    Is state alpha? true
    Is state alphanumeric? true
    Is state alphaspace? true

10.取得某字符串在另一字符串中出現的次數
使用函數:StringUtils.countMatches(testString,seqString)
函數介紹:取得seqString在testString中出現的次數,未發現則返回零
例程:
System.out.println(StringUtils.countMatches( "Chinese People", "e"
));
輸出:
4

11.部分截取字符串
使用函數:
StringUtils.substringBetween(testString,fromString,toString ):取得兩字符
之間的字符串
StringUtils.substringAfter( ):取得指定字符串後的字符串
StringUtils.substringBefore( )：取得指定字符串之前的字符串
StringUtils.substringBeforeLast( )：取得最後一個指定字符串之前的字符串
StringUtils.substringAfterLast( )：取得最後一個指定字符串之後的字符串

函數介紹：上面應該都講明白了吧。
例程：
    String formatted = " 25 * (30,40) [50,60] | 30";
    System.out.print("N0: " + StringUtils.substringBeforeLast( formatted, "*" ) );
    System.out.print(", N1: " + StringUtils.substringBetween( formatted, "(", "," ) );
    System.out.print(", N2: " + StringUtils.substringBetween( formatted, ",", ")" ) );
    System.out.print(", N3: " + StringUtils.substringBetween( formatted, "[", "," ) );
    System.out.print(", N4: " + StringUtils.substringBetween( formatted, ",", "]" ) );
    System.out.print(", N5: " + StringUtils.substringAfterLast( formatted, "|" ) );
輸出如下：
    N0: 25 , N1: 30, N2: 40, N3: 50, N4: 40) [50,60, N5: 30

1. 檢查字符串是否爲空：

static boolean isBlank(CharSequence str) 判斷字符串是否爲空或null;
static boolean isNotBlank(CharSequence str) 判斷字符串是否非空或非null;

StringUtils.isBlank("a");
返回結果爲: false;

2. 縮進字符串：

static String abbreviate(String str, int maxWidth) 縮進字符串，第二個參數至少爲4（包括...）

StringUtils.abbreviate("abcdefg", 20);
返回結果爲：abcdefg （正常顯示）

StringUtils.abbreviate("abcdefg", 4);
返回結果爲：a...

3. 首字母大寫：

static String capitalize(String str) 首字母大寫
static String uncapitalize(String str)首字母小寫

StringUtils.capitalize("abcdefg");
返回結果：Abcdefg

4. 字符串顯示在一個大字符串的位置：

static String center(String str, int size); 默認以空格填充
static String center(String str, int size, String padString); 其餘位置字符串填充
public static String leftPad(String str,int size); 左側空格填充
public static String leftPad(String str,int size,String padStr);左側字符串填充
public static String rightPad(String str,int size); 左側空格填充
public static String rightPad(String str,int size,String padStr);左側字符串填充

StringUtils.center("abcdefg", 20)；
返回結果： abcdefg

StringUtils.center("abcdefg", 20,"*_");
返回結果：*_*_*_abcdefg*_*_*_*

StringUtils.leftPad("abc", 10, "*");
返回結果：*******abc

5. 重複字符串次數

static String repeat(String str, int repeat);

StringUtils.repeat("abc", 5);
返回結果：abcabcabcabcabc

6. 是否全是大寫，是否全是小寫（3.0版本）

public static boolean isAllLowerCase(String str);
public static boolean isAllUpperCase(String str);

StringUtils.isAllLowerCase("abC");
返回結果：false

7. 是否都是由字母組成：

public static boolean isAlpha(String str); 只由字母組成
public static boolean isAlphaSpace(String str); 只有字母和空格組成
public static boolean isAlphanumeric(String str);只由字母和數字組成
public static boolean isAlphanumericSpace(String str);只由字母數字和空格組成
public static boolean isNumeric(String str);只由數字組成
public static boolean isNumericSpace(String str);只由數字和空格組成

StringUtils.isAlpha("a2bdefg");
返回結果：false

8. 小字符串在大字符串中的匹配次數

public static int countMatches(String str,String sub);

StringUtils.countMatches("ababsssababa", "ab");
返回結果：4

9. 字符串倒轉

public static String reverse(String str);

StringUtils.reverse("abcdef");
返回結果：fedcba

10. 大小寫轉換，空格不動

public static String swapCase(String str);

StringUtils.swapCase("I am a-A*a")
返回結果：i AM A-a*A

StringUtils工具類的使用

一、數組轉成字符串：
1、將數組中的字符轉換爲一個字符串
將數組中的字符轉換爲一個字符串

@param strToConv 要轉換的字符串 ,默認以逗號分隔
@return 返回一個字符串
String[3] s={"a","b","c"}
StringUtil.convString（s)="a,b,c"
2、 static public String converString(String strToConv)
@param strToConv 要轉換的字符串 ,
@param conv 分隔符,默認以逗號分隔
@return 同樣返回一個字符串

String[3] s={"a","b","c"}
StringUtil.convString（s,"@")="a@b@c"
static public String converString(String strToConv, String conv)

二、空值檢測：
3、

Checks if a String is empty ("") or null.

判斷一個字符串是否爲空，空格作非空處理。 StringUtils.isEmpty(null) = true StringUtils.isEmpty("") = true StringUtils.isEmpty(" ") = false StringUtils.isEmpty("bob") = false StringUtils.isEmpty(" bob ") = false

NOTE: This method changed in Lang version 2.0.

It no longer trims the String.
That functionality is available in isBlank().

@param str the String to check, may be null
@return true if the String is empty or null
public static boolean isEmpty(String str)

三、非空處理：
4、
Checks if a String is not empty ("") and not null.

判斷一個字符串是否非空，空格作非空處理. StringUtils.isNotEmpty(null) = false StringUtils.isNotEmpty("") = false StringUtils.isNotEmpty(" ") = true StringUtils.isNotEmpty("bob") = true StringUtils.isNotEmpty(" bob ") = true

@param str the String to check, may be null
@return true if the String is not empty and not null
public static boolean isNotEmpty(String str)

5、

Checks if a String is not empty (""), not null and not whitespace only.

判斷一個字符串是否非空，空格作空處理. StringUtils.isNotBlank(null) = false StringUtils.isNotBlank("") = false StringUtils.isNotBlank(" ") = false StringUtils.isNotBlank("bob") = true StringUtils.isNotBlank(" bob ") = true

@param str the String to check, may be null
@return true if the String is
not empty and not null and not whitespace
@since 2.0
public static boolean isNotBlank(String str)

四、空格處理
6、
Removes control characters (char <= 32) from both

ends of this String, handling null by returning
null.

The String is trimmed using {@link String#trim()}.

Trim removes start and end characters <= 32.
To strip whitespace use {@link //strip(String)}.

To trim your choice of characters, use the

{@link //strip(String, String)} methods.

格式化一個字符串中的空格，有非空判斷處理； StringUtils.trim(null) = null StringUtils.trim("") = "" StringUtils.trim(" ") = "" StringUtils.trim("abc") = "abc" StringUtils.trim(" abc ") = "abc"

@param str the String to be trimmed, may be null
@return the trimmed string, null if null String input
public static String trim(String str)

7、

Removes control characters (char <= 32) from both

ends of this String returning null if the String is
empty ("") after the trim or if it is null.

The String is trimmed using {@link String#trim()}.

Trim removes start and end characters <= 32.
To strip whitespace use {@link /stripToNull(String)}.

格式化一個字符串中的空格，有非空判斷處理，如果爲空返回null； StringUtils.trimToNull(null) = null StringUtils.trimToNull("") = null StringUtils.trimToNull(" ") = null StringUtils.trimToNull("abc") = "abc" StringUtils.trimToNull(" abc ") = "abc"

@param str the String to be trimmed, may be null
@return the trimmed String,
null if only chars <= 32, empty or null String input
@since 2.0
public static String trimToNull(String str)

8、

Removes control characters (char <= 32) from both

ends of this String returning an empty String ("") if the String
is empty ("") after the trim or if it is null.

The String is trimmed using {@link String#trim()}.

Trim removes start and end characters <= 32.
To strip whitespace use {@link /stripToEmpty(String)}.

格式化一個字符串中的空格，有非空判斷處理，如果爲空返回""； StringUtils.trimToEmpty(null) = "" StringUtils.trimToEmpty("") = "" StringUtils.trimToEmpty(" ") = "" StringUtils.trimToEmpty("abc") = "abc" StringUtils.trimToEmpty(" abc ") = "abc"

@param str the String to be trimmed, may be null
@return the trimmed String, or an empty String if null input
@since 2.0
public static String trimToEmpty(String str)

五、字符串比較:
9、
Compares two Strings, returning true if they are equal.

nulls are handled without exceptions. Two null

references are considered to be equal. The comparison is case sensitive.

判斷兩個字符串是否相等，有非空處理。 StringUtils.equals(null, null) = true StringUtils.equals(null, "abc") = false StringUtils.equals("abc", null) = false StringUtils.equals("abc", "abc") = true StringUtils.equals("abc", "ABC") = false

@param str1 the first String, may be null
@param str2 the second String, may be null
@return true if the Strings are equal, case sensitive, or
both null
@see Java.lang.String#equals(Object)
public static boolean equals(String str1, String str2)

10、

Compares two Strings, returning true if they are equal ignoring

the case.

nulls are handled without exceptions. Two null

references are considered equal. Comparison is case insensitive.

判斷兩個字符串是否相等，有非空處理。忽略大小寫 StringUtils.equalsIgnoreCase(null, null) = true StringUtils.equalsIgnoreCase(null, "abc") = false StringUtils.equalsIgnoreCase("abc", null) = false StringUtils.equalsIgnoreCase("abc", "abc") = true StringUtils.equalsIgnoreCase("abc", "ABC") = true

@param str1 the first String, may be null
@param str2 the second String, may be null
@return true if the Strings are equal, case insensitive, or
both null
@see java.lang.String#equalsIgnoreCase(String)
public static boolean equalsIgnoreCase(String str1, String str2)

六、 IndexOf 處理
11、

Finds the first index within a String, handling null.

This method uses {@link String#indexOf(String)}.

A null String will return -1.

返回要查找的字符串所在位置，有非空處理 StringUtils.indexOf(null, *) = -1 StringUtils.indexOf(*, null) = -1 StringUtils.indexOf("", "") = 0 StringUtils.indexOf("aabaabaa", "a") = 0 StringUtils.indexOf("aabaabaa", "b") = 2 StringUtils.indexOf("aabaabaa", "ab") = 1 StringUtils.indexOf("aabaabaa", "") = 0

@param str the String to check, may be null
@param searchStr the String to find, may be null
@return the first index of the search String,
-1 if no match or null string input
@since 2.0
public static int indexOf(String str, String searchStr)

12、

Finds the first index within a String, handling null.

This method uses {@link String#indexOf(String, int)}.

A null String will return -1.

A negative start position is treated as zero.
An empty ("") search String always matches.
A start position greater than the string length only matches
an empty search String.

返回要由指定位置開始查找的字符串所在位置，有非空處理 StringUtils.indexOf(null, *, *) = -1 StringUtils.indexOf(*, null, *) = -1 StringUtils.indexOf("", "", 0) = 0 StringUtils.indexOf("aabaabaa", "a", 0) = 0 StringUtils.indexOf("aabaabaa", "b", 0) = 2 StringUtils.indexOf("aabaabaa", "ab", 0) = 1 StringUtils.indexOf("aabaabaa", "b", 3) = 5 StringUtils.indexOf("aabaabaa", "b", 9) = -1 StringUtils.indexOf("aabaabaa", "b", -1) = 2 StringUtils.indexOf("aabaabaa", "", 2) = 2 StringUtils.indexOf("abc", "", 9) = 3

@param str the String to check, may be null
@param searchStr the String to find, may be null
@param startPos the start position, negative treated as zero
@return the first index of the search String,
-1 if no match or null string input
@since 2.0
public static int indexOf(String str, String searchStr, int startPos)

七、子字符串處理：
13、
Gets a substring from the specified String avoiding exceptions.

A negative start position can be used to start n

characters from the end of the String.

A null String will return null.

An empty ("") String will return "".

返回指定位置開始的字符串中的所有字符 StringUtils.substring(null, *) = null StringUtils.substring("", *) = "" StringUtils.substring("abc", 0) = "abc" StringUtils.substring("abc", 2) = "c" StringUtils.substring("abc", 4) = "" StringUtils.substring("abc", -2) = "bc" StringUtils.substring("abc", -4) = "abc"

@param str the String to get the substring from, may be null
@param start the position to start from, negative means
count back from the end of the String by this many characters
@return substring from start position, null if null String input
public static String substring(String str, int start)

14、

Gets a substring from the specified String avoiding exceptions.

A negative start position can be used to start/end n

characters from the end of the String.

The returned substring starts with the character in the start

position and ends before the end position. All postion counting is
zero-based -- i.e., to start at the beginning of the string use
start = 0. Negative start and end positions can be used to
specify offsets relative to the end of the String.

If start is not strictly to the left of end, ""

is returned.

返回由開始位置到結束位置之間的子字符串 StringUtils.substring(null, *, *) = null StringUtils.substring("", * , *) = ""; StringUtils.substring("abc", 0, 2) = "ab" StringUtils.substring("abc", 2, 0) = "" StringUtils.substring("abc", 2, 4) = "c" StringUtils.substring("abc", 4, 6) = "" StringUtils.substring("abc", 2, 2) = "" StringUtils.substring("abc", -2, -1) = "b" StringUtils.substring("abc", -4, 2) = "ab"

@param str the String to get the substring from, may be null
@param start the position to start from, negative means
count back from the end of the String by this many characters
@param end the position to end at (exclusive), negative means
count back from the end of the String by this many characters
@return substring from start position to end positon,
null if null String input
public static String substring(String str, int start, int end)

15、 SubStringAfter/SubStringBefore（前後子字符串處理：

Gets the substring before the first occurance of a separator.

The separator is not returned.

A null string input will return null.

An empty ("") string input will return the empty string.
A null separator will return the input string.

返回指定字符串之前的所有字符 StringUtils.substringBefore(null, *) = null StringUtils.substringBefore("", *) = "" StringUtils.substringBefore("abc", "a") = "" StringUtils.substringBefore("abcba", "b") = "a" StringUtils.substringBefore("abc", "c") = "ab" StringUtils.substringBefore("abc", "d") = "abc" StringUtils.substringBefore("abc", "") = "" StringUtils.substringBefore("abc", null) = "abc"

@param str the String to get a substring from, may be null
@param separator the String to search for, may be null
@return the substring before the first occurance of the separator,
null if null String input
@since 2.0
public static String substringBefore(String str, String separator)

16、

Gets the substring after the first occurance of a separator.

The separator is not returned.

A null string input will return null.

An empty ("") string input will return the empty string.
A null separator will return the empty string if the
input string is not null.

返回指定字符串之後的所有字符 StringUtils.substringAfter(null, *) = null StringUtils.substringAfter("", *) = "" StringUtils.substringAfter(*, null) = "" StringUtils.substringAfter("abc", "a") = "bc" StringUtils.substringAfter("abcba", "b") = "cba" StringUtils.substringAfter("abc", "c") = "" StringUtils.substringAfter("abc", "d") = "" StringUtils.substringAfter("abc", "") = "abc"

@param str the String to get a substring from, may be null
@param separator the String to search for, may be null
@return the substring after the first occurance of the separator,
null if null String input
@since 2.0
public static String substringAfter(String str, String separator)

17、

Gets the substring before the last occurance of a separator.

The separator is not returned.

A null string input will return null.

An empty ("") string input will return the empty string.
An empty or null separator will return the input string.

返回最後一個指定字符串之前的所有字符 StringUtils.substringBeforeLast(null, *) = null StringUtils.substringBeforeLast("", *) = "" StringUtils.substringBeforeLast("abcba", "b") = "abc" StringUtils.substringBeforeLast("abc", "c") = "ab" StringUtils.substringBeforeLast("a", "a") = "" StringUtils.substringBeforeLast("a", "z") = "a" StringUtils.substringBeforeLast("a", null) = "a" StringUtils.substringBeforeLast("a", "") = "a"

@param str the String to get a substring from, may be null
@param separator the String to search for, may be null
@return the substring before the last occurance of the separator,
null if null String input
@since 2.0
public static String substringBeforeLast(String str, String separator)

18、

Gets the substring after the last occurance of a separator.

The separator is not returned.

A null string input will return null.

An empty ("") string input will return the empty string.
An empty or null separator will return the empty string if
the input string is not null.

返回最後一個指定字符串之後的所有字符 StringUtils.substringAfterLast(null, *) = null StringUtils.substringAfterLast("", *) = "" StringUtils.substringAfterLast(*, "") = "" StringUtils.substringAfterLast(*, null) = "" StringUtils.substringAfterLast("abc", "a") = "bc" StringUtils.substringAfterLast("abcba", "b") = "a" StringUtils.substringAfterLast("abc", "c") = "" StringUtils.substringAfterLast("a", "a") = "" StringUtils.substringAfterLast("a", "z") = ""

@param str the String to get a substring from, may be null
@param separator the String to search for, may be null
@return the substring after the last occurance of the separator,
null if null String input
@since 2.0
public static String substringAfterLast(String str, String separator)

八、 Replacing（字符串替換）
19、
Replaces all occurances of a String within another String.

A null reference passed to this method is a no-op.

以指定字符串替換原來字符串的的指定字符串 StringUtils.replace(null, *, *) = null StringUtils.replace("", *, *) = "" StringUtils.replace("aba", null, null) = "aba" StringUtils.replace("aba", null, null) = "aba" StringUtils.replace("aba", "a", null) = "aba" StringUtils.replace("aba", "a", "") = "aba" StringUtils.replace("aba", "a", "z") = "zbz"

@param text text to search and replace in, may be null
@param repl the String to search for, may be null
@param with the String to replace with, may be null
@return the text with any replacements processed,
null if null String input
@see #replace(String text, String repl, String with, int max)
public static String replace(String text, String repl, String with)

20、

Replaces a String with another String inside a larger String,

for the first max values of the search String.

A null reference passed to this method is a no-op.

以指定字符串最大替換原來字符串的的指定字符串 StringUtils.replace(null, *, *, *) = null StringUtils.replace("", *, *, *) = "" StringUtils.replace("abaa", null, null, 1) = "abaa" StringUtils.replace("abaa", null, null, 1) = "abaa" StringUtils.replace("abaa", "a", null, 1) = "abaa" StringUtils.replace("abaa", "a", "", 1) = "abaa" StringUtils.replace("abaa", "a", "z", 0) = "abaa" StringUtils.replace("abaa", "a", "z", 1) = "zbaa" StringUtils.replace("abaa", "a", "z", 2) = "zbza" StringUtils.replace("abaa", "a", "z", -1) = "zbzz"

@param text text to search and replace in, may be null
@param repl the String to search for, may be null
@param with the String to replace with, may be null
@param max maximum number of values to replace, or -1 if no maximum
@return the text with any replacements processed,
null if null String input
public static String replace(String text, String repl, String with, int max)

九、 Case conversion（大小寫轉換）
21、

Converts a String to upper case as per {@link String#toUpperCase()}.

A null input String returns null.

將一個字符串變爲大寫 StringUtils.upperCase(null) = null StringUtils.upperCase("") = "" StringUtils.upperCase("aBc") = "ABC"

@param str the String to upper case, may be null
@return the upper cased String, null if null String input
public static String upperCase(String str) 22、

Converts a String to lower case as per {@link String#toLowerCase()}.

A null input String returns null.

將一個字符串轉換爲小寫 StringUtils.lowerCase(null) = null StringUtils.lowerCase("") = "" StringUtils.lowerCase("aBc") = "abc"

@param str the String to lower case, may be null
@return the lower cased String, null if null String input
public static String lowerCase(String str) 23、

Capitalizes a String changing the first letter to title case as

per {@link Character#toTitleCase(char)}. No other letters are changed.

For a word based alorithm, see {@link /WordUtils#capitalize(String)}.

A null input String returns null.

StringUtils.capitalize(null) = null StringUtils.capitalize("") = "" StringUtils.capitalize("cat") = "Cat" StringUtils.capitalize("cAt") = "CAt"

@param str the String to capitalize, may be null
@return the capitalized String, null if null String input
@see /WordUtils#capitalize(String)
@see /uncapitalize(String)
@since 2.0
將字符串中的首字母大寫
public static String capitalize(String str)