2.2 Testing the Rect Class

Example 2-2 is a standalone program named RectTest that puts the Rect class of Example 2-1 through its paces. Note the use of the new keyword and the Rect( ) constructor to create new Rect objects. The program uses the . operator to invoke methods of the Rect objects and to access their fields. The test program also relies implicitly on the toString( ) method of Rect when it uses the string concatenation operator (+) to create strings to be displayed to the user.

Example 2-2. RectTest.java

package je3.classes;

/** This class demonstrates how you might use the Rect class */
public class RectTest {
    public static void main(String[  ] args) {
        Rect r1 = new Rect(1, 1, 4, 4);    // Create Rect objects
        Rect r2 = new Rect(2, 3, 5, 6);
        Rect u = r1.union(r2);             // Invoke Rect methods
        Rect i = r2.intersection(r1);
        
        if (u.isInside(r2.x1, r2.y1))   // Use Rect fields and invoke a method
            System.out.println("(" + r2.x1 + "," + r2.y1 +
                               ") is inside the union");
        
        // These lines implicitly call the Rect.toString( ) method
        System.out.println(r1 + " union " + r2 + " = " + u);
        System.out.println(r1 + " intersect " + r2 + " = " + i);
    }
}