使用java中，面向对象封装+继承的方法算题

class Bu
{
    private String str;
    public Bu(){}
    public Bu(String str){
        this.str = str;
    }
    public String getStr(){
        return str;
    }
    public void setStr(String str){
        this.str = str;
    }
    public String getInfo(){
        return str;
    }
}
class Rvs extends Bu //负责翻转
{
    public Rvs(){}
    public Rvs(String str){
        super(str);
    }
    public void m(){ //给定字符串，逆序输出字符串
       String temp = ""; //定义新的字符串变量负责接收逆序后的字符串
        char[] chs = super.getStr().toCharArray();
        for(int i = chs.length-1;i >= 0;i--){ 
            temp += chs[i];
        }
        super.setStr(temp);
    }
}
class Oth extends Rvs //去掉数字和空格
{
    public Oth(){}
    public Oth(String str){
        super(str);
    }
    public void m2(){
        String temp = "";
        char[] chs = super.getStr().toCharArray(); //先去掉数字
        for(int i = 0;i < chs.length;i++){
            if(chs[i] >= ‘0‘ && chs[i] <= ‘9‘){
                continue;
            }
            temp += chs[i];
        }
        temp = temp.replace(" ",""); //再去空格，用replace()方法
        super.setStr(temp);
    }
}
class Statt 
{
    public static void main(String[] args) 
    {    
        //Rvs r = new Rvs("4m 897ou // ");
        //r.m();
        //System.out.println(r.getInfo());
        Oth oth = new Oth("4m 897ou // ");
        oth.m(); //字符串的逆序
        oth.m2(); //逆序后字符串去掉空格和数字
        System.out.println(oth.getInfo()); //最后输出是getInfo()内容

    } 
}

package com.oracle.acm.prac;

class X{
	private int n;
	private int count; //次数
	public X(){
		count=0;
	}
	public X(int n){
		count=0;
		this.n=n;
	}
	public void changeNum(){
		//若n为奇数，则将n变为3n+1，否则变为n的一半
		if(n%2!=0){
			n=3*n+1;
		}else{
			n=n/2;
		}
	}
	public int getChangeCount(){
		//经过若干次这样的变换，一定会使n变为1.求输出变换的次数
		while(n!=1){
			this.changeNum();
			count++;
		}
		return count%3; //要求次数要对3取余
	}
}
public class Demo10 {
	public static void main(String[] args) {
		X x=new X(2);
		System.out.println(x.getChangeCount());
	}
}