Question

I am making a GUI of Stack using Java. Here is my code

     private void StackActionPerformed(java.awt.event.ActionEvent evt) 
    {

      b1=new JButton("Push");
      b2=new JButton("Pop");
      b3=new JButton("Peek");
      b4=new JButton("Clear");
      b1.addActionListener(new java.awt.event.ActionListener() {
        public void actionPerformed(java.awt.event.ActionEvent evt) {
            pushButtonActionPerformed(evt);
        }
      });
      tb.add(b1);
      tb.add(b2);
      tb.add(b3);
      tb.add(b4);
      frame_st.add(tb);
      frame_st.setExtendedState(Frame.MAXIMIZED_BOTH);

  }

Here I am adding buttons to my toolBar (tb) everything is working fine . I am not getting any error. But after compiling am not getting the desired result . toolBar(tb) is not able to add the buttons (b1,b2,etc)

Answer 1

If you’re adding components after a GUI has been rendered, don’t forget to revalidate and repaint containers after you’ve changed the components they hold.

private void StackActionPerformed(java.awt.event.ActionEvent evt) 
{
   b1=new JButton("Push");
   b2=new JButton("Pop");
   b3=new JButton("Peek");
   b4=new JButton("Clear");
   b1.addActionListener(new java.awt.event.ActionListener() {
      public void actionPerformed(java.awt.event.ActionEvent evt) {
         pushButtonActionPerformed(evt);
      }
   });
   tb.add(b1);
   tb.add(b2);
   tb.add(b3);
   tb.add(b4);    
   frame_st.add(tb);
   frame_st.setExtendedState(Frame.MAXIMIZED_BOTH);
   JPanel contentPane = (JPanel)frame.getContentPane();
   contentPane.revalidate();
   contentPane.repaint();
}

Also key here are what layout managers are your tb JPanel and JFrame contentPane using?