Java Code: Find the Error - Swing Components 1. The following statement is in a

Question

Java Code: Find the Error - Swing Components

1. The following statement is in a class that uses Swing components:

     import java.swing.*;

2. The following is an inner class that will be registered as an action listener for a JButton component:

     private class ButtonListener implements ActionListener

{

     public void actionPerformed( )

     {

          // Code appears here

     }

}

3. The intention of the following statement is to give the panel object a GridLayout manager with 10 columns and 5 rows:

panel.setLayout(new GridLayout(10, 5) );

4. The panel variable references a JPanel governed by a BorderLayout manager. The following statement attempts to add the button component to the north region of panel:

panel.add(button, NORTH);

5. The panel variable references a JPanel object. The intention of the following statement is to create a titled border around panel:

panel.setBorder(new BorderFactory(*Choices*) );

Explanation / Answer

1) There is NO java.swing package in Java

But there is a package which is used for Swing components is

javax.swing.*;

2) There is No Error in this code, creating the Listener class when ever button's are clicked (We have private class in inner class)

private class ButtonListener implements ActionListener

{

     public void actionPerformed( )

     {

          // Code appears here

     }

}

for the first time i didn't recognize the paramater for actionPerformed() so we have ActionEvent as a parameter for actionPerformed(),

so finally code look's like

private class ButtonListener implements ActionListener

{

     public void actionPerformed(ActionEvent ae)

     {

          // Code appears here

     }

}

3) GridLayout(int rows ,int columns);

so error is 10 columns and 5 rows.

correct ans is 10 rows and 5 columns.

if you want 10 columns and 5 rows use following

panel.setLayout(new GridLayout(5,10));

4) if panel is governed by BorderLayout but still you need to mention the BorderLayout.NORTH to place the button in North region of Layout.

panel.add(button,BorderLayout.NORTH);

Sysntax : panel.add(BUTTON, Region);

5) BorderFactory class is used to sets the Border(Bounds) of layout.

there is no String argument for BorderFactory class

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