Java String split()

split() 方法根据匹配给定的正则表达式来拆分字符串。
注意： . 、 $、 | 和 * 等转义字符，必须得加 \\。
注意：多个分隔符，可以用 | 作为连字符。

1 语法

public String split(String regex) 
 
或

public String split(String regex, int limit)  

2 参数

regex ： 正则表达式分隔符。
limit ： 分割的份数。

3 返回值

字符串数组。

4 split()内部源码

public String[] split(String regex, int limit) {  
        /* fastpath if the regex is a 
         (1)one-char String and this character is not one of the 
            RegEx's meta characters ".$|()[{^?*+\\", or 
         (2)two-char String and the first char is the backslash and 
            the second is not the ascii digit or ascii letter. 
         */  
        char ch = 0;  
        if (((regex.value.length == 1 &&  
             ".$|()[{^?*+\\".indexOf(ch = regex.charAt(0)) == -1) ||  
             (regex.length() == 2 &&  
              regex.charAt(0) == '\\' &&  
              (((ch = regex.charAt(1))-'0')|('9'-ch)) < 0 &&  
              ((ch-'a')|('z'-ch)) < 0 &&  
              ((ch-'A')|('Z'-ch)) < 0)) &&  
            (ch < Character.MIN_HIGH_SURROGATE ||  
             ch > Character.MAX_LOW_SURROGATE))  
        {  
            int off = 0;  
            int next = 0;  
            boolean limited = limit > 0;  
            ArrayList<String> list = new ArrayList<>();  
            while ((next = indexOf(ch, off)) != -1) {  
                if (!limited || list.size() < limit - 1) {  
                    list.add(substring(off, next));  
                    off = next + 1;  
                } else {    // last one  
                    //assert (list.size() == limit - 1);  
                    list.add(substring(off, value.length));  
                    off = value.length;  
                    break;  
                }  
            }  
            // If no match was found, return this  
            if (off == 0)  
                return new String[]{this};  
  
            // Add remaining segment  
            if (!limited || list.size() < limit)  
                list.add(substring(off, value.length));  
  
            // Construct result  
            int resultSize = list.size();  
            if (limit == 0)  
                while (resultSize > 0 && list.get(resultSize - 1).length() == 0)  
                    resultSize--;  
            String[] result = new String[resultSize];  
            return list.subList(0, resultSize).toArray(result);  
        }  
        return Pattern.compile(regex).split(this, limit);  
    }  

5 split()示例1

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java String.split方法的例子
 */
public class Demo{

    public static void main(String args[]){
        String s1="java string split method by yiidian";
        String[] words=s1.split("\\s");//根据空格分割字符串
        //使用Java的foreach循环来打印字符串数组的元素
        for(String w:words){
            System.out.println(w);
        }
    }
}

输出结果为：

java
string
split
method
by
yiidian

6 split()示例2

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java String.split方法的例子
 */
public class Demo{

    public static void main(String args[]){
        String s1="welcome to split world";
        System.out.println("returning words:");
        for(String w:s1.split("\\s",0)){
            System.out.println(w);
        }
        System.out.println("returning words:");
        for(String w:s1.split("\\s",1)){
            System.out.println(w);
        }
        System.out.println("returning words:");
        for(String w:s1.split("\\s",2)){
            System.out.println(w);
        }

    }
}

输出结果为：

returning words:
welcome
to
split
world
returning words:
welcome to split world
returning words:
welcome
to split world

7 split()示例3

split的第二个参数用于限制分隔字符串的数量。

package com.yiidian;

/**
 * 一点教程网： http://www.yiidian.com
 */
/**
 * Java String.split方法的例子
 */
public class Demo {

    public static void main(String[] args) {
        String str = "Yiidian";
        System.out.println("Returning words:");
        String[] arr = str.split("t", 0);
        for (String w : arr) {
            System.out.println(w);
        }
        System.out.println("Split array length: "+arr.length);
    }
}

输出结果为：

Returning words:
Yiidian
Split array length: 1