Question

6. Which of the following classes define a legal abstract class? 1: class A 2: abstract void unfinished 4: 1: public class abstract A 2: abstract void unfinished 1: class A 2: abstract void unfinished 3: 1: abstract class A 2: protected void unfinished 3: 1: abstract class A 2: abstract void unfinished 3: 1: class A 2: abstract int unfinished 3: 7. Suppose A is an interface. Can you create an instance using "new A() 8. Which of the following (if any) is a correct interface? (Assume I1 and 12 are correctly defined elsewhere.) 1: interface A 2: void print 3: 4: 1: abstract interface A extends I1, 12 2: abstract void print 3: 4: 1: abstract interface A print 1: interface A 2: void print 3:

java questions , help me and answer them please !

Answer 1

6. The following classes define a legal abstract class

public class abstract A
{
   abstract void unfinished()
   {

   }
}

abstract class A
{
   protected void unfinished();
}

abstract class A
{
   abstract void unfinished();
}

7. Yes. We Can Create Instance Like this

interface A
{
    void print();
}
public class myclass
{
    public static void main(String args[])
    {
        A obj=new A() {

            public void print()
            {
                throw new UnsupportedOperationException("Not supported yet.");
            }
        };
}

8. The following is a correct interface
interface A
{
   void print();
}
Abstract Interfaces:
Every interface is implicitly abstract. This modifier is obsolete and should not be used in new programs.

Abstract Method Declarations:
For compatibility with older versions of the Java platform, it is permitted but discouraged, as a matter of style, to redundantly specify the abstract modifier for methods declared in interfaces.

9.
a) A layout manager is an object that implements the LayoutManager interface* and determines the size and position of the components within a container. Although components can provide size and alignment hints, a container's layout manager has the final say on the size and position of the components within the container.

b) JFrame's default Layout Manager is BorderLayout.

10.

public class reverse extends JFrame
{
    public reverse()
    {
        add(new Button("OK"));

    }
    public static void main(String args[])
    {

        JFrame frame = new JFrame();
        frame.setSize(100,200);
        frame.setVisible(true);

}

Correct Method is

public class reverse extends JFrame
{
    public reverse()
    {
        add(new Button("OK"));

    }
    public static void main(String args[])
    {

        Test frame = new Test();
        frame.setSize(100,200);
        frame.setVisible(true);

}
The problem is you are calling new JFrame instead call the class that extends JFrame