简化字符串

package com;

import java.util.Scanner;

public class Text1 {
	public static void main(String[] args){
		Scanner r = new Scanner(System.in);
		while(true){
			System.out.println("请输入字符串[限制为abcd，个数不限,相同元素间不可存在其他元素]：");
			String s = r.next();
			System.out.println("输入的字符串为："+s);
			
			
			String a1=s.substring(s.indexOf("a"),s.lastIndexOf("a")+1);
            System.out.println("简化前a1段:"+a1);
//            int x=s.indexOf("b");
//            int y=s.lastIndexOf("b");
//            String b1=s.substring(x,y-x);
            String b1=s.substring(s.indexOf("b"),s.lastIndexOf("b")+1);
            System.out.println("简化前b1段:"+b1);
            String c1=s.substring(s.indexOf("c"),s.lastIndexOf("c")+1);
            System.out.println("简化前c1段:"+c1);
            String d1=s.substring(s.indexOf("d"),s.lastIndexOf("d")+1);
            System.out.println("简化前d1段:"+d1);
			int n1=a1.length();
			int n2=b1.length();
			int n3=c1.length();
			int n4=d1.length();
			String a2;//a1简化后
			String b2;//b1简化后
			String c2;//c1简化后
			String d2;//d1简化后
			if(a1.length()>1){
				a2 = n1+"a";
				System.out.println("简化后a2段为："+a2);
			}else{
				a2="a";
				System.out.println("简化后a2段为："+a2);
			}
			if(b1.length()>1){
				
				b2 = n2+"b";
				System.out.println("简化后b2段为："+b2);
			}else{
				b2="b";
				System.out.println("简化后b2段为："+b2);
			}
			if(c1.length()>1){
				
				c2 = n3+"c";
				System.out.println("简化后c2段为："+c2);
			}else{
				c2="c";
				System.out.println("简化后c2段为："+c2);
			}
			if(d1.length()>1){
				
				d2 = n4+"d";
				System.out.println("简化后d2段为："+d2);
			}else{
				d2="d";
				System.out.println("简化后d2段为："+d2);
			}
			String sum;
			String sum1 = s.replaceAll(a1, a2);
			String sum2 = sum1.replaceAll(b1, b2);
			String sum3 = sum2.replaceAll(c1, c2);
			String sum4 = sum3.replaceAll(d1, d2);
			System.out.println("简化后的字符串为："+sum4);
		}
	}
}