java里怎么把一个字符串里的特定子串删除

从cc++转到java需要点时间

先上个只删除一个的代码

package test;
import java.math.*;
import java.util.*;

public class test1 {//一个文件中只能有一个public类
public static void main (String[] args) {

    String s1 = " this a my exemple ";

    String s2 = "my";


    if(s1.startsWith(s2)){
        s1 = s1.substring(s2.length());
    }else if(s1.endsWith(s2)){
        s1 =  s1.substring(0, s1.length()-s2.length());
    }else {
        int index = s1.indexOf(s2);
        if(index!=-1){
            String s11 = s1.substring(0, index);
            String s22 = s1.substring(index+s2.length());
            s1 = s11 + s22;
        }
    }

    System.out.println(s1);



    }
}

万一要删除多个呢？

package test;
import java.math.*;
import java.util.*;
public class test1 {//一个文件中只能有一个public类
public static void main (String[] args) {

    String s1 = " my this a my exemple my ";

    String s2 = "my";


    int index = s1.indexOf(s2);
    while(index != -1){
        String s11 = s1.substring(0, index);
        String s22 = s1.substring(index + s2.length());
        s1 = s11 + s22;
        index = s1.indexOf(s2);
    }
    System.out.println(s1);
}

}

其实挺简单的