Chapter: Java The Complete Reference : The Java Language : A Closer Look at Methods and Classes

Returning Objects - Java

A method can return any type of data, including class types that you create.

Returning Objects

A method can return any type of data, including class types that you create. For example, in the following program, the incrByTen( ) method returns an object in which the value of a is ten greater than it is in the invoking object.

// Returning an object.

class Test {

int a;

Test(int i) { a = i;

}

Test incrByTen() {

Test temp = new Test(a+10); return temp;

}

class RetOb {

public static void main(String args[]) { Test ob1 = new Test(2);

Test ob2;

ob2 = ob1.incrByTen(); System.out.println("ob1.a: " + ob1.a); System.out.println("ob2.a: " + ob2.a);

ob2 = ob2.incrByTen();

System.out.println("ob2.a after second increase: " + ob2.a);

}

The output generated by this program is shown here:

ob1.a: 2

ob2.a: 12

ob2.a after second increase: 22

As you can see, each time incrByTen( ) is invoked, a new object is created, and a reference to it is returned to the calling routine.

The preceding program makes another important point: Since all objects are dynamically allocated using new, you don’t need to worry about an object going out-of-scope because the method in which it was created terminates. The object will continue to exist as long as there is a reference to it somewhere in your program. When there are no references to it, the object will be reclaimed the next time garbage collection takes place.

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Java The Complete Reference : The Java Language : A Closer Look at Methods and Classes : Returning Objects - Java |