Method Trace APCS

public class MethodTracing {
    public static void main(String[] args) {
        InstanceMethods im=new InstanceMethods();
        int i1=4, i2=5;
        int i3=im.method1(i1,i2);
        System.out.println(i3);
        System.out.println(i1+ " "+ i2);


        String aString="Hello";
        String anotherString="world";
        String output=im.method2(aString, anotherString);
        System.out.println(output);

        String s4=im.combineMethods(im.method2(anotherString, aString), im.method1(i1,i2));
        System.out.println(s4);
    }

}


public class InstanceMethods {

//    int i1=4, i2=5;
//    int i3=im.method1(i1,i2);
    public int method1(int n1, int n2){
        //n1=9 n2=5
        int n3=0;
        //n3=0;
        n3=n1+n2;
        //n3=14
        return n3;
    }

//    String aString="Hello";
//    String anotherString="world";
//    String output=im.method2(aString, anotherString);
    public String method2(String s1, String s2){
        //s1="w H", s2="G"
        s1=s1.substring(0,1);
        //s1="w"
        s2=s2.substring(s2.length()-1);
        //s2="G"
        String s3=s1+" "+s2;
        //s3="w G"
        return s3;
    }

    //param1="w H" param2=9
    public String combineMethods(String s1, int i1){
        int n2=method1(i1, 5);
        //n2=14
        String s2=method2(s1, "G");
        //s2=w G
        //return w G 14
        return s2+" "+n2;
    }

}