java中将字符串翻转的几种方法

末蓝、 2022-05-24 23:41 194阅读 0赞

对于字符串处理问题，笔试中我们经常会遇到直接或间接的需要将字符串翻转（颠倒）的问题，下面介绍（但不限于）几种方法：

方法1：使用toCharArray( )方法，然后反向赋值

import java.util.*;
    public class Test5{
        public static void main(String[] args){
            Scanner sc = new Scanner(System.in);
            while(sc.hasNext()){
                char[] c1 = sc.next().toCharArray();
                int len = c1.length;
                char[] c2 = new char[len];
                for(int i = 0; i < len; i ++){
                    c2[i] = c1[len-1-i];
                }
                String res = new String(c2);
                System.out.println(res);
            }
        }
    }

方法2：使用StringBuilder类的reverse( )方法

import java.util.Scanner;
    public class Main{
        public static void main(String[] args){
            Scanner sc = new Scanner(System.in);
            while(sc.hasNext()){
                System.out.println(new StringBuilder(sc.next()).reverse());
            }
        }
    }

方法3：若只考虑输出，不考虑返回

import java.util.Scanner;
    public class Main{
        public static void main(String[] args){
            Scanner sc = new Scanner(System.in);
            while(sc.hasNext()){
                String s = sc.next();
            	for(int i = s.length()-1; i >= 0; i--)
            		System.out.print(s.charAt(i));
            }
        }
    }

方法4：使用collections的静态方法reverse( )

import java.util.*;
    public class Test5{
        public static void main(String[] args){
            Scanner sc = new Scanner(System.in);
            while(sc.hasNext()){
            	/*
            	char[] c = sc.next().toCharArray();
            	List<Character> list = new ArrayList<Character>();
            	for(int i =0;i<c.length;i++)
            		list.add(c[i]);
            	Collections.reverse(list);
            	for(Character cha:list)
            		System.out.print(cha);
            		*/
            	String[] s = sc.nextLine().split("");
            	List<String> list = Arrays.asList(s);
            	Collections.reverse(list);
            	for(String s1:list)
            		System.out.print(s1);
            }
        }
    }