String split 分隔字符串，多个分隔符、正则表达式学习示例

import java.util.Arrays;

import org.junit.Test;

/**
 * 通过几个例子学习String split方法
 * 尤其是记住使用多个分隔符的方式
 * @author lzg
 *
 */
public class StringSplitTest {

	/**
	 * 待分隔的字符串全是由分隔符组成
	 */
	@Test
	public void test1(){
		String str = ",,,,,,";
		String [] strArray = str.split(",");		

		System.out.printf("length: %d \n",strArray.length);
		//length: 0
		System.out.printf("content: %s",Arrays.toString(strArray));
		//content: []

	}

	/**
	 * 若有多个分隔符，需放在中括号之中
	 */
	@Test
	public void test2(){
		String str = ",,:,;,";
		String [] strArray = str.split("[,;:]");

		System.out.printf("length: %d \n",strArray.length);
		//length: 0
		System.out.printf("content: %s",Arrays.toString(strArray));
		//content: []

	}

	/**
	 * 左侧遇到非分隔字符前，分隔后内容为空也会保留。最右侧分隔后的内容若为空会忽略
	 */
	@Test
	public void test3(){
		String str = ",ab,cd,efgh,,,";
		String [] strArray = str.split(",");	

		System.out.printf("length: %d \n",strArray.length);
		//length: 4
		System.out.printf("content: %s",Arrays.toString(strArray));
		//content: [, ab, cd, efgh]

	}

	/**
	 * 左侧遇到非分隔字符前，分隔后内容为空也会保留。最右侧分隔后的内容若为空会忽略
	 */
	@Test
	public void test4(){
		String str = ",ab,cd:efgh,;,";
		String [] strArray = str.split("[,;:]");

		System.out.printf("length: %d \n",strArray.length);
		//length: 4
		System.out.printf("content: %s",Arrays.toString(strArray));
		//content: [, ab, cd, efgh]

	}

	/**
	 * 若分隔符为正则表达式的特殊字符，则需进行转义
	 */
	@Test
	public void test5(){
		String str = "*ab*cd*efgh***";
		String [] strArray = str.split("\\*");	

		System.out.printf("length: %d \n",strArray.length);
		//length: 4
		System.out.printf("content: %s",Arrays.toString(strArray));
		//content: [, ab, cd, efgh]

	}

	/**
	 * 分隔符为正则表达式的特殊字符，则需进行转义。若中括号本身为分隔符，则需进行转义
	 */
	@Test
	public void test6(){
		String str = "*ab+cd^efgh[[[";
		String [] strArray = str.split("[\\*\\+\\[^]");	

		System.out.printf("length: %d \n",strArray.length);
		//length: 4
		System.out.printf("content: %s",Arrays.toString(strArray));
		//content: [, ab, cd, efgh]
	}

	/**
	 * 多个分隔符之间可以用|分隔，也可以不用。若|为分隔符，则需进行转义
	 */
	@Test
	public void test7(){
		String str = "*ab+cd^efgh[[[";
		String [] strArray = str.split("[\\*|\\+|\\[|^]");	

		System.out.printf("length: %d \n",strArray.length);
		//length: 4
		System.out.printf("content: %s",Arrays.toString(strArray));
		//content: [, ab, cd, efgh]
	}

	/**
	 * 使用标准的正则
	 */
	@Test
	public void test8(){
		String str = "*ab+cd^efgh----234---[[.....[";
		String [] strArray = str.split("\\W+"); //注意正则表达式所代表的含义	

		System.out.printf("length: %d \n",strArray.length);
		//length: 5
		System.out.printf("content: %s",Arrays.toString(strArray));
		//content: [, ab, cd, efgh, 234]
	}

	/**
	 * split还有一种带限制的方式，可以指定最多匹配出多少个串
	 */
	@Test
	public void test9(){
		String str = "*ab+cd^efgh----234---[[.....[";
		String [] strArray = str.split("\\W+",3); //限制最多匹配出3个串	

		System.out.printf("length: %d \n",strArray.length);
		//length: 3
		System.out.printf("content: %s",Arrays.toString(strArray));
		//content: [, ab, cd^efgh----234---[[.....[]
	}

}