1. ArrayList()

import java.util.*; public class Test{    public static void main(String [] args){        ArrayList list = new ArrayList();        list.add("a");        list.add("b");        list.add("c");        System.out.println("size:" + list.size());        System.out.println("contain:a?:" + list.contains("a"));        System.out.println("contain:d?:" + list.contains("d"));        }}

输出

size:3contain:a?:truecontain:d?:false

 

2. 数组

public class TestNew  {       public static void main(String args[]) {           int[] s ;           int i ;           s = new int[5] ;           for(i = 0 ; i < 5 ; i++) { s[i] = i ; } for(i = 4 ; i >= 0 ; i--) { System.out.println("" + s[i]) ; } } }

 

3. 字符串类型

trim(): 将String两端的空白字符删除

案例

import java.util.*;public class SplitDemo{    public static void main(String[] args)    {        String input = "\t This!!\t";        String input2 = input.trim();        System.out.println(input + ":" + input.length()); System.out.println(input2 + ":" + input2.length()); } }

结果

This!!	:9This!!:6

split(): 以某个字符串切割

例子

import java.util.*;public class SplitDemo{    public static void main(String[] args)    {        String input = "This!! umusual use!!of exclamation!!points";        System.out.println(input);        String arrayS1[] = input.split("!!");        System.out.println(Arrays.toString(arrayS1));        String arrayS2[] = input.split("!!", 3); System.out.println(Arrays.toString(arrayS2)); } }

结果

This!! umusual use!!of exclamation!!points[This,  umusual use, of exclamation, points][This,  umusual use, of exclamation!!points]

说明

split()第二个参数表示分割的字符串个数不超过该参数