反转字符串的方法，例如将java反转成avaj。

package com.scau.learn;

import java.io.ByteArrayInputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.Stack;
//学习于importnew
public class ReverseString {

    //使用+号连接字符，charAt获取。
    public String reverseStringByConcat(String in) {
        String out =new String();
        for(int i=(in.length()-1);i>=0;i--)
            out+=(in.charAt(i));
        System.out.println("ReverseJavaString.reverseStringByConcat():"+out);
        return out;
    }
    //使用StringBuilder,直接reserve
    public String reverseStringByStringBuilder(String in) {
        StringBuilder builder=new StringBuilder(in);//StringBuilder参数构造，非线程安全的吧
        System.out.println("reverseStringByStringBuilder():"+builder.reverse().toString());
        return builder.reverse().toString();
    }
    //使用StringBuilder和charAt
    public String reverseStringByStringBuilderAndCharAt(String in) {
        StringBuilder builder=new StringBuilder();
        for(int i=(in.length()-1);i>=0;i--)
             builder.append(in.charAt(i));
        System.out.println("ReverseJavaString.reverseStringByStringBuilderAndCharAt():"+builder.toString());
        return builder.toString();
    }
    //循环反转
    public String reverseStringBySwap(String in ) {
        final char[] array=in.toCharArray();//这个方法可以有
        final int length=array.length-1;
        final int harf=(int)(array.length/2);
        char swap;
        for(int i=length;i>harf;i--)
        {
            swap=array[length-i];
            array[length-i]=array[i];
            array[i]=swap;
        }
        System.out.println("ReverseString.reverseStringBySwap():"+array.toString());
        System.out.println("ReverseString.reverseStringBySwap()"+String.valueOf(array));
        //这样提取array做字符串的吗
        return array.toString();
    }
    //通过XOR操作符
    public String reverseStringByXor(String in) {
        return "还没懂";
    }
    //使用堆栈
    public String reverseStringByStack(String in) {
        if(in==null||in.equals(""))
            return in;
        Stack<Character> stack=new Stack<Character>();
        char[] array=in.toCharArray();
        for(int i=0;i<array.length;i++) {
            stack.push(array[i]);
        }
        int n=0;
        while(!stack.isEmpty()) {
            array[n]=stack.pop();
            n++;
        }
        System.out.println("ReverseString.reverseStringByStack():"+String.valueOf(array));
        return String.valueOf(array);
    }
    //使用集合
    public String reverseStringByCollection(String in) {
        if(in==null||in.equals(""))
            return in;
        List<Character> list=new ArrayList<Character>();
        for(char ch:in.toCharArray()) {
            list.add(ch);
        }
        Collections.reverse(list);//反转的66的
        list.toString();
        System.out.println("ReverseString.reverseStringByCollection()list.toString"+list.toString());
        StringBuilder builder=new StringBuilder();
        for(char ch:list)
            builder.append(ch);
        System.out.println("ReverseString.reverseStringByCollection()"+builder.toString());
        return builder.toString();
    }
    //使用byte数组
    public String reverseStringByBytes(String in) {
        if(in==null||in.equals(""))
           return in;
        byte[] bytes=in.getBytes();//有用的方法呀
        for(int i=0,j=(in.length()-1);i<j;i++,j--) {
            byte temp=bytes[i];
            bytes[i]=bytes[j];
            bytes[j]=temp;
        }
        System.out.println("ReverseString.reverseStringByBytes()"+new String(bytes));
        return new String(bytes);
    }
    //使用substring和递归,还可以使用递归转换实现
    public String reverseStringBySub(String in) {
        if(in==null||in.equals(""))
            return in;
        //System.out.println("ReverseString.reverseStringBySub()");
        return in.charAt(in.length()-1)+reverseStringBySub(in.substring(0,in.length()-1));
    }
    //http://tonyan416.iteye.com/blog/1192634 
    //classnotfoundexception
    public static void main(String[] args) {
        // TODO 自动生成的方法存根
        ReverseString str=new ReverseString();
         System.out.println("ReverseString.main()");
        str.reverseStringByConcat("javascript");
        str.reverseStringByStringBuilder("javascript");
        str.reverseStringByStringBuilderAndCharAt("javascript");
        str.reverseStringBySwap("JAVASCRIPT");
        str.reverseStringBySwap("javascript");
        str.reverseStringByCollection("javascript");
        str.reverseStringByBytes("javascript");
        System.out.println(str.reverseStringBySub("javascript"));
       
        //str.reverseStringByConcat("javascript");
    }
    

}

• charAt(int)z直接在String中取字符。
• char[] array=in.toCharArray()字符串变字符数组
• stringbuilder参数实例化对象，增加元素后变字符串
• 栈进出操作
• 字符数组变字符串String.valueOf()
• 集合的包不要导错
• 集合反转，集合数组toString直接会带逗号
• 字符串getBytes，字节数组变字符串
• 递归和substring

StringBuffer 方法

以下是 StringBuffer 类支持的主要方法：