一、數組轉成字符串：
1、 將數組中的字符轉換為一個字符串
將數組中的字符轉換為一個字符串
@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 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 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為空，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，如果為空返回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，如果為空返回""； 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)
