Question

I have a class called A and there’s a String declared in it. And i have 2 other classes B and C which is inherited from A

public abstract class A {
    protected String ss="";

    public abstract String someMethod();
}

public class B extends A{
    public String someMethod(){
        int i=8;
        return ss+="$"+i;
    }
}

public class C extends A {
    public String someMethod() {
        int i=9;
       return ss+="$"+i;
    }
}

Test Code:

A aa = new B();
aa.someMethod();

A aaa = new C();    
aaa.someMethod();

When I print aaa.someMethod(); – why haven’t the strings from class B and C been appended? I want them to be appended. How can I do this ?

Answer 1

/usr/lib/jvm/java-1.7.0-openjdk-amd64/bin/javac A.java B.java C.java Test.java

/usr/lib/jvm/java-1.7.0-openjdk-amd64/bin/java Test

$8
$9

nothing surprising here, B method someMethod() calls B method, C method someMethod() calls C method…

file A.java:

public abstract class A
{
    protected String ss="";
    public abstract String someMethod();
}

file B.java

public class B extends A
{
    public String someMethod()
    {
        int i=8;
        return ss+="$"+i;
    }
}

file C.java

public class C extends A
{
    public String someMethod()
    {
        int i=9;
        return ss+="$"+i;
    }
}

file Test.java

public class Test
{
    public static void main(String pArgs[])
    {
        A aa = new B();
        System.out.println(aa.someMethod());
        A aaa = new C();
        System.out.println(aaa.someMethod());
    }
}