63 lines
1.8 KiB
Java
63 lines
1.8 KiB
Java
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// Demonstrate instanceof operator.
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class A {
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int i, j;
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}
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class B {
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int i, j;
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}
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class C extends A {
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int k;
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}
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class D extends A {
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int k;
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}
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#stuff
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class InstanceOf {
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public static void main(String args[]) {
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A a = new A();
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B b = new B();
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C c = new C();
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D d = new D();
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if(a instanceof A)
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System.out.println("a is instance of A");
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if(b instanceof B)
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System.out.println("b is instance of B");
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if(c instanceof C)
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System.out.println("c is instance of C");
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if(c instanceof A)
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System.out.println("c can be cast to A");
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if(a instanceof C)
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System.out.println("a can be cast to C");
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System.out.println();
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// compare types of derived types
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A ob;
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ob = d; // A reference to d
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System.out.println("ob now refers to d");
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if(ob instanceof D)
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System.out.println("ob is instance of D");
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System.out.println();
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ob = c; // A reference to c
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System.out.println("ob now refers to c");
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if(ob instanceof D)
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System.out.println("ob can be cast to D");
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else
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System.out.println("ob cannot be cast to D");
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if(ob instanceof A)
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System.out.println("ob can be cast to A");
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else
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System.out.println();
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// all objects can be cast to Object
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if(a instanceof Object)
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System.out.println("a may be cast to Object");
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if(b instanceof Object)
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System.out.println("b may be cast to Object");
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if(c instanceof Object)
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System.out.println("c may be cast to Object");
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if(d instanceof Object)
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System.out.println("d may be cast to Object");
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}
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}
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