Java The Complete Reference, Seventh Edition

414 Part II: The Java Library

The following program implementsCloneableand defines the methodcloneTest( ),

which callsclone( )inObject:

// Demonstrate the clone() method.

class TestClone implements Cloneable {

int a;

double b;

// This method calls Object's clone().

TestClone cloneTest() {

try {

// call clone in Object.

return (TestClone) super.clone();

} catch(CloneNotSupportedException e) {

System.out.println("Cloning not allowed.");

return this;

}

}

}

class CloneDemo {

public static void main(String args[]) {

TestClone x1 = new TestClone();

TestClone x2;

x1.a = 10;

x1.b = 20.98;

x2 = x1.cloneTest(); // clone x1

System.out.println("x1: " + x1.a + " " + x1.b);

System.out.println("x2: " + x2.a + " " + x2.b);

}

}

Here, the methodcloneTest( )callsclone( )inObjectand returns the result. Notice that the

object returned byclone( )must be cast into its appropriate type (TestClone).

The following example overridesclone( )so that it can be called from code outside of its

class. To do this, its access specifier must bepublic, as shown here:

// Override the clone() method.

class TestClone implements Cloneable {

int a;

double b;

// clone() is now overridden and is public.

public Object clone() {

try {

// call clone in Object.

return super.clone();

} catch(CloneNotSupportedException e) {