将字符串中的单词倒序输出

 

package wang.yong.x;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

// 写一个方法将字符串中的单词倒序，例如："tom is cat"倒序结果为"cat is tom"
public class Test2 {
    public static void main(String[] args) {
        String str = "tom is cat";
//        String str2 = m(str);
//        System.out.println("str2 = "+str2);    
        System.out.println("==========");
        System.out.println("str2 = "+n(str));
        System.out.println("==========");
        System.out.println(w(str));
    }
    
    // ArrayList的存入和取出顺序一直
    public static String w(String str){
        String[] string = str.split(" ");
        String str2 = "";
        List<String> list  = new ArrayList<>();
        for(int i = string.length-1;i>=0;i--){
            list.add(string[i]);
            str2+=string[i]+" ";
        }
        //string = list.toArray(string);
        //return Arrays.toString(string);
        return str2;
    }
    
    // 直接数组元素对换
    public static String n(String str){
        String[] string = str.split(" ");
        String str2 = "";
        for(int start =0, end=string.length-1;start<end;start++,end--){
                String temp = string[end];
                string[end] = string[start];
                string[start] = temp;
        }
        for(int i = 0;i<string.length;i++){
            str2+=string[i]+" ";
        }
        return str2;
    }
    
    // 使用collections和Arrays工具类
    public static String m(String str){
        String[] string = str.split(" ");
        Collections.reverse(Arrays.asList(string));
        String str2="";
        for(int i=0;i<string.length;i++){
            str2=str2+string[i]+" ";
        }
        return str2;
    }
}