Chapter 23 Exercise 18, Introduction to Java Programming, Tenth Edition Y. Daniel LiangY.

23.18 (Merge animation) Write a program that animates the merge of two sorted lists. Create two arrays, list1 and list2 , each of which consists of 8 random num-
bers from 1 to 999. The array elements are displayed, as shown in Figure 23.22a. Clicking the Step button causes the program to move an element from list1 or list2 to temp . Clicking the Reset button creates two new random arrays for a new start. When the algorithm is finished, clicking the Step button displays a message to inform the user.

import javax.swing.*;

import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.ArrayList;
import java.util.Collections;

public class Exercise18 extends JApplet {

 private static final long serialVersionUID = 1L;
 private MergePanel mergePanel = new MergePanel();
 private JButton jButton1 = new JButton("Step");
 
 public Exercise18() {
  setLayout(new BorderLayout());
  add(mergePanel, BorderLayout.CENTER);
  
  JPanel panel1 = new JPanel();  
  panel1.add(jButton1);
  JButton jButton2 = new JButton("Reset");
  panel1.add(jButton2);
  add(panel1, BorderLayout.SOUTH); 
  
  jButton1.addActionListener(new ActionListener() {   
   @Override
   public void actionPerformed(ActionEvent e) {
    mergePanel.nextStep();
   }
  });
  
  jButton2.addActionListener(new ActionListener() {   
   @Override
   public void actionPerformed(ActionEvent e) {
    mergePanel.reset();
    jButton1.setEnabled(true);
   }
  });
 }
 
 class MergePanel extends JPanel {
  private static final long serialVersionUID = 1L;
  private int searchSize = 10;
  private ArrayList<Integer> list1 = new ArrayList<>();
  private ArrayList<Integer> list2 = new ArrayList<>();
  private ArrayList<Integer> temp = new ArrayList<>();
  private int current1 = 0;
  private int current2 = 0;
  
  public MergePanel() {
   reset();
  }
  
  public void nextStep() {

   if (current1 < list1.size() && current2 < list2.size()) {
    if (list1.get(current1) < list2.get(current2))
     temp.add(list1.get(current1++));
    else
     temp.add(list2.get(current2++));
   } else if (current1 < list1.size()) {
    temp.add(list1.get(current1++));
   } else if (current2 < list2.size()) {
    temp.add(list2.get(current2++));
   }
   if(temp.size() == list1.size() + list2.size()) { 
    jButton1.setEnabled(false);
   }
     
   repaint();  
  }
  
  public void reset() {
   temp.clear();
   list1.clear();
   for (int i = 1; i <= searchSize; i++) {
    list1.add((int)(Math.random() * 1000));
   }
   Collections.sort(list1);
   list2.clear();
   for (int i = 1; i <= searchSize; i++) {
    list2.add((int)(Math.random() * 1000));
   }
   Collections.sort(list2);
   current1 = 0;
   current2 = 0;
   repaint();
  }
  
  @Override
  protected void paintComponent(Graphics g) {
   super.paintComponent(g);
   int numberWidth = getWidth() / (searchSize * 2 + 3);
   int numberHeight = 40;
   
   if(current1 < list1.size()) {
    g.drawString("current1",  (int)(numberWidth * (1.0 + current1)), 28);
    g.drawLine((int)(numberWidth * (1.5 + current1)), 30,  (int)(numberWidth * (1.5 + current1)), 100);
    g.drawLine((int)(numberWidth * (1.5 + current1)) - 15, 100 - 15,  (int)(numberWidth * (1.5 + current1)), 100);
    g.drawLine((int)(numberWidth * (1.5 + current1)) + 15, 100 - 15,  (int)(numberWidth * (1.5 + current1)), 100);
   }
   
   g.drawString("list1", 15, 130);
   for (int i = 0; i < searchSize; i++) {
    g.drawRect(numberWidth * (i + 1), 100, numberWidth, numberHeight);
    g.drawString(list1.get(i) + "", numberWidth * (i + 1) + 5, 130);
   }
   
   if(current2 < list2.size()) {
    g.drawString("current2",  (int)(numberWidth * (12.0 + current2)), 28);
    g.drawLine((int)(numberWidth * (12.5 + current2)), 30,  (int)(numberWidth * (12.5 + current2)), 100);
    g.drawLine((int)(numberWidth * (12.5 + current2)) - 15, 100 - 15,  (int)(numberWidth * (12.5 + current2)), 100);
    g.drawLine((int)(numberWidth * (12.5 + current2)) + 15, 100 - 15,  (int)(numberWidth * (12.5 + current2)), 100);
   }
   
   g.drawString("list2", numberWidth * 11 + 15, 130);
   for (int i = 0; i < searchSize; i++) {
    g.drawRect(numberWidth * (i + 12), 100, numberWidth, numberHeight);
    g.drawString(list2.get(i) + "", numberWidth * (i + 12) + 5, 130);
   }
   
   
   if(temp.size() < list1.size() + list2.size()) {
    g.drawString("current3",  (int)(numberWidth * (1.0 + temp.size())), 320);
    g.drawLine((int)(numberWidth * (1.5 + temp.size())), 310,  (int)(numberWidth * (1.5 + temp.size())), 240);
    g.drawLine((int)(numberWidth * (1.5 + temp.size())) - 15, 240 + 15,  (int)(numberWidth * (1.5 + temp.size())), 240);
    g.drawLine((int)(numberWidth * (1.5 + temp.size())) + 15, 240 + 15,  (int)(numberWidth * (1.5 + temp.size())), 240);
   }
   g.drawString("temp", 10, 230);
   for (int i = 0; i < searchSize * 2; i++) {
    g.drawRect(numberWidth * (i + 1), 200, numberWidth, numberHeight);
    if(i < temp.size()) {
     g.drawString(temp.get(i) + "", numberWidth * (i + 1) + 5, 230);
    }
   }
  }

 }

 public static void main(String[] args) {
  JFrame frame = new JFrame("Exercise18");
  Exercise18 applet = new Exercise18();
  frame.add(applet);
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.setSize(960, 500);
  frame.setMinimumSize(new Dimension(frame.getWidth(), frame.getHeight()));
  frame.setLocationRelativeTo(null);
  frame.setVisible(true);
 }
}