FamilyVsExactType.java

// The difference between instanceof and class
package thinkinginjava.typeinfo;

import static thinkinginjava.util.Print.print;

//P333

/**
 * Testing x of type class thinkinginjava.typeinfo.Base
 * x instanceof Base true
 * x instanceof Derived false
 * Base.isInstance(x) true
 * Derived.isInstance(x) false
 * x.getClass() == Base.class true
 * x.getClass() == Derived.class false
 * x.getClass().equals(Base.class)) true
 * x.getClass().equals(Derived.class)) false
 * ==================
 * Testing x of type class thinkinginjava.typeinfo.Derived
 * x instanceof Base true
 * x instanceof Derived true
 * Base.isInstance(x) true
 * Derived.isInstance(x) true
 * x.getClass() == Base.class false
 * x.getClass() == Derived.class true
 * x.getClass().equals(Base.class)) false
 * x.getClass().equals(Derived.class)) true
 */

class Base {
}

class Derived extends Base {
}

public class FamilyVsExactType {

    static void test(Object x) {
        print("Testing x of type " + x.getClass());
        print("x instanceof Base " + (x instanceof Base));
        print("x instanceof Derived " + (x instanceof Derived));
        print("Base.isInstance(x) " + Base.class.isInstance(x));
        print("Derived.isInstance(x) " + Derived.class.isInstance(x));
        print("x.getClass() == Base.class " + (x.getClass() == Base.class));
        print("x.getClass() == Derived.class " + (x.getClass() == Derived.class));
        print("x.getClass().equals(Base.class)) " + (x.getClass().equals(Base.class)));
        print("x.getClass().equals(Derived.class)) " + (x.getClass().equals(Derived.class)));
    }

    public static void main(String[] args) {
        test(new Base());
        System.out.println("==================");
        test(new Derived());
    }
}