title: Why won't my GUI work properly?
body: <p>Why is it that when the GUI I can press A, B, and C but if I click A and then C it
  (the GUI) doesn't change and vice versa but if I click B it will work for all? I don't understand? Please if anyone notices any mistakes or something let me know. And ps I'm a beginner so please if you can explain in layman's terms. Thank you </p>
  
  <pre><code>package Experimental;
  
  import javax.swing.*;
  import java.awt.*;
  import java.awt.event.ActionEvent;
  import java.awt.event.ActionListener;
  
  public class EventListener2 extends JFrame implements ActionListener{
      JButton a,b,c;
      JLabel aa,bb,cc;
      JPanel top, bottom;
      EventListener2(){
          super("Event Listener 2");
          setSize(300,300);
          setLayout(new FlowLayout());
          a=new JButton("A");
          aa = new JLabel("Button \"A\" was pressed");
          b=new JButton("B");
          bb = new JLabel("Button \"B\" was pressed");
          c=new JButton("C");
          cc = new JLabel("Button \"C\" was pressed");
          setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  
          a.addActionListener(this);
          b.addActionListener(this);
          c.addActionListener(this);
  
          top=new JPanel();
          top.setLayout(new FlowLayout());
          top.add(a);
          top.add(b);
          top.add(c);
          bottom=new JPanel();
  
          this.add(top);
          this.add(bottom);
  
          setVisible(true);
      }
  
      @Override
      public void actionPerformed(ActionEvent event) {
          // TODO Auto-generated method stub
          Object source = event.getSource();
          bottom.removeAll();
          if (source==a){
              bottom.add(aa);
              System.out.println("a was pressed");
          }
          else if (source==b){
              bottom.add(bb);
              System.out.println("b was pressed");
          }
          else{
              bottom.add(cc);
              System.out.println("c was pressed");
          }
          this.setVisible(true);
  
      }
      public static void main(String[] args) {
           EventListener2 a = new EventListener2();
      }
  
  }
  </code></pre>