org.apache.commons.lang.StringUtils的常用方法

org.apache.commons.lang.StringUtils是apache的commons-lang-x.x.jar下的包，里面包含很多字符串操作方法，

官網(http://commons.apache.org/proper/commons-lang/javadocs/api-release/index.html)介紹的常用方法如下：

public class StringUtils
extends Object

Operations on String that are null safe.

• IsEmpty/IsBlank - checks if a String contains text
• Trim/Strip - removes leading and trailing whitespace
• Equals/Compare - compares two strings null-safe
• startsWith - check if a String starts with a prefix null-safe
• endsWith - check if a String ends with a suffix null-safe
• IndexOf/LastIndexOf/Contains - null-safe index-of checks
• IndexOfAny/LastIndexOfAny/IndexOfAnyBut/LastIndexOfAnyBut - index-of any of a set of Strings
• ContainsOnly/ContainsNone/ContainsAny - does String contains only/none/any of these characters
• Substring/Left/Right/Mid - null-safe substring extractions
• SubstringBefore/SubstringAfter/SubstringBetween - substring extraction relative to other strings
• Split/Join - splits a String into an array of substrings and vice versa
• Remove/Delete - removes part of a String
• Replace/Overlay - Searches a String and replaces one String with another
• Chomp/Chop - removes the last part of a String
• AppendIfMissing - appends a suffix to the end of the String if not present
• PrependIfMissing - prepends a prefix to the start of the String if not present
• LeftPad/RightPad/Center/Repeat - pads a String
• UpperCase/LowerCase/SwapCase/Capitalize/Uncapitalize - changes the case of a String
• CountMatches - counts the number of occurrences of one String in another
• IsAlpha/IsNumeric/IsWhitespace/IsAsciiPrintable - checks the characters in a String
• DefaultString - protects against a null input String
• Rotate - rotate (circular shift) a String
• Reverse/ReverseDelimited - reverses a String
• Abbreviate - abbreviates a string using ellipsis or another given String
• Difference - compares Strings and reports on their differences
• LevenshteinDistance - the number of changes needed to change one String into another

部分方法的示例：

package com.led.test;

import org.apache.commons.lang.StringUtils;

public class Test3 {
    @SuppressWarnings("deprecation")
    public static void main(String[] args) {
        //找到2個字符串第一個出現不同的位置（1開始）
        String difference = StringUtils.difference("s123", "s13");
        System.out.println(difference);//3
        
        //判斷2個字符串是否相等
        boolean equals = StringUtils.equals("s1", "s1");
        System.out.println(equals);//true

        //判斷字符串里面是否含有特定字符串
        boolean b2 = StringUtils.contains("asd", "as");
        System.out.println(b2);//true

        //把數組的元素用:進行拼接
        String concatStr = StringUtils.join(new String[]{"dog", "cat", "monkey"},":");
        System.out.println(concatStr);//dog:cat:monkey

        //根據特定分隔符對字符串進行拆分
        String[] split = StringUtils.split("apple|xiaomi|dell|lenovo", "|");
        for (String s1 : split) {
            System.out.print(s1 + "、");//apple、xiaomi、dell、lenovo、
        }
        System.out.println();
        
        //所有單詞首字母大寫
        String capitaliseAllWords = StringUtils.capitaliseAllWords("today i will go to china");
        System.out.println(capitaliseAllWords);//Today I Will Go To China

        //統計某個字符串在字符串出現的次數
        int matchCount = StringUtils.countMatches("Happy Birthday to you", "o");
        System.out.println(matchCount);//2

        //必須要8位，不夠的就拿0去字符串左邊補 
        String leftPad = StringUtils.leftPad("54", 8, "0");
        System.out.println(leftPad);//00000054
        
        //必須要8位，不夠的就拿0去字符串右邊補 
        String rightPad = StringUtils.rightPad("54", 8, "0");
        System.out.println(rightPad);//54000000

        //判斷字符串是否以特定字符串開頭，區分大小寫
        boolean startsWith = StringUtils.startsWith("GoodMorning", "go");
        System.out.println(startsWith);//false
        
        //判斷字符串是否以特定字符串開頭，區分大小寫
        boolean endsWith = StringUtils.endsWith("GoodMorning", "ing");
        System.out.println(endsWith);//true

    }
}