冒泡排序动画 [英] Bubble sort animation
问题描述
最近我注意到一些关于使用循环算法的代码动画的问题.例如:
Lately I've noticed questions asking about animation of code that uses a looping algorithm. For example:
现有代码有效，但只显示最终结果.所以人们想要为算法的每一步设置动画.提出问题的原因是:
The existing code works but only displays the final result. So people want to animate each step of the algorithm. A question is asked because:
- 他们不知道该怎么做，或者
- 已将 Thread.sleep(...) 添加到算法中，以允许间歇性绘画，但绘画仍仅在循环完成后更新.当然，我们知道问题在于您不能在 EDT 上使用 Thread.sleep(...).
在这两种情况下，建议都是使用 Swing Timer 并且该问题已作为重复项关闭.但有那么容易吗?
In both cases the suggestion was to use a Swing Timer and the question was closed as a duplicate. But is it that easy?
下面的代码演示了一个简单的冒泡排序算法.排序逻辑简单且自包含在单个方法中，并指示动画应该发生的位置.
The code below demonstrates a simple Bubble Sort algorithm. The sorting logic is simple and self contained in a single method and indicates where the animation should occur.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.Timer;
public class BubbleSort extends JPanel
{
private final static int BAR_WIDTH = 30;
private final static int BAR_HEIGHT_MAX = 400;
private int[]items;
public BubbleSort(int[] items)
{
this.items = items;
}
public void setItems(int[] items)
{
this.items = items;
repaint();
}
public void sort()
{
int n = items.length;
int temp = 0;
for (int i = 0; i < n; i++)
{
for (int j = 1; j < (n - i); j++)
{
if (items[j-1] > items[j])
{
temp = items[j - 1];
items[j - 1] = items[j];
items[j] = temp;
// paint current state for animation
repaint();
try { Thread.sleep(100); } catch (Exception e) {}
}
}
}
}
@Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
for (int i = 0; i < items.length; i++)
{
int x = i * BAR_WIDTH;
int y = getHeight() - items[i];
g.setColor( Color.RED );
g.fillRect(x, y, BAR_WIDTH, items[i]);
g.setColor( Color.BLUE );
g.drawString("" + items[i], x, y);
}
}
@Override
public Dimension getPreferredSize()
{
return new Dimension(items.length * BAR_WIDTH, BAR_HEIGHT_MAX + 20);
}
public static int[]generateRandomNumbers()
{
int[] items = new int[10];
for(int i = 0; i < items.length; i++)
{
items[i] = (int)(Math.random() * BubbleSort.BAR_HEIGHT_MAX);
}
return items;
}
private static void createAndShowGUI()
{
BubbleSort bubbleSort = new BubbleSort( BubbleSort.generateRandomNumbers() );
JButton generate = new JButton("Generate Data");
generate.addActionListener((e) -> bubbleSort.setItems( BubbleSort.generateRandomNumbers() ) );
JButton sort = new JButton("Sort Data");
sort.addActionListener((e) -> bubbleSort.sort());
JPanel bottom = new JPanel();
bottom.add( generate );
bottom.add( sort );
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(bubbleSort, BorderLayout.CENTER);
frame.add(bottom, BorderLayout.PAGE_END);
frame.pack();
frame.setLocationByPlatform( true );
frame.setVisible( true );
}
public static void main(String[] args) throws Exception
{
EventQueue.invokeLater( () -> createAndShowGUI() );
}
}
所以问题是:
- 如何更改代码以使用 Swing Timer?您有什么提示/指示?
- 是否有其他方法可以代替 Swing Timer?
推荐答案
另一种方法可能是使用 SwingWorker.
Another approach might be to use a SwingWorker.
SwingWorker 在其自己的线程中创建运行并允许您发布"断断续续的结果要画.
The SwingWorker creates runs in its own Thread and allows you to "publish" intermittent results to be painted.
下面方法的关键是将数据的副本传递给 SwingWorker.这允许工作人员在重新绘制数据时对数据进行排序，因此您不必担心数组中的数据处于不一致状态.
The key to the approach below is that a copy of the data is passed to the SwingWorker. This allows the worker to sort the data while the data is being repainted so you don't have to worry about the data in the array being in an inconsistent state.
每次循环代码迭代后，数组的新状态都会更新，以便可以绘制.
After each iteration of the looping code the new state of the array is updated so it can be painted.
这使您可以轻松地将排序逻辑移到 SwingWorker 中，而无需重构.
This allows you to easily move the sorting logic into the SwingWorker without refactoring.
import java.awt.*;
import java.awt.event.*;
import java.util.Arrays;
import java.util.List;
import javax.swing.*;
import javax.swing.Timer;
public class BubbleSortWorker extends JPanel
{
private final static int BAR_WIDTH = 30;
private final static int BAR_HEIGHT_MAX = 400;
private int[]items;
public BubbleSortWorker(int[] items)
{
this.items = items;
}
public void setItems(int[] items)
{
this.items = items;
repaint();
}
public void sort()
{
new SortWorker(items).execute();
}
@Override
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
for (int i = 0; i < items.length; i++)
{
int x = i * BAR_WIDTH;
int y = getHeight() - items[i];
g.setColor( Color.RED );
g.fillRect(x, y, BAR_WIDTH, items[i]);
g.setColor( Color.BLUE );
g.drawString("" + items[i], x, y);
}
}
@Override
public Dimension getPreferredSize()
{
return new Dimension(items.length * BAR_WIDTH, BAR_HEIGHT_MAX + 20);
}
class SortWorker extends SwingWorker<Void, int[]>
{
private int[] items;
public SortWorker(int[] unsortedItems)
{
items = Arrays.copyOf(unsortedItems, unsortedItems.length);
}
@Override
protected Void doInBackground()
{
int n = items.length;
int temp = 0;
for (int i = 0; i < n; i++)
{
for (int j = 1; j < (n - i); j++)
{
if (items[j-1] > items[j])
{
temp = items[j - 1];
items[j - 1] = items[j];
items[j] = temp;
//repaint();
publish( Arrays.copyOf(items, items.length) );
try { Thread.sleep(100); } catch (Exception e) {}
}
}
}
return null;
}
@Override
protected void process(List<int[]> list)
{
int[] items = list.get(list.size() - 1);
setItems( items );
}
@Override
protected void done() {}
}
public static int[]generateRandomNumbers()
{
int[] items = new int[10];
for(int i = 0; i < items.length; i++)
{
items[i] = (int)(Math.random() * BubbleSortWorker.BAR_HEIGHT_MAX);
}
return items;
}
private static void createAndShowGUI()
{
BubbleSortWorker bubbleSort = new BubbleSortWorker( BubbleSortWorker.generateRandomNumbers() );
JButton generate = new JButton("Generate Data");
generate.addActionListener((e) -> bubbleSort.setItems( BubbleSortWorker.generateRandomNumbers() ) );
JButton sort = new JButton("Sort Data");
sort.addActionListener((e) -> bubbleSort.sort());
JPanel bottom = new JPanel();
bottom.add( generate );
bottom.add( sort );
JFrame frame = new JFrame("SSCCE");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(bubbleSort, BorderLayout.CENTER);
frame.add(bottom, BorderLayout.PAGE_END);
frame.pack();
frame.setLocationByPlatform( true );
frame.setVisible( true );
}
public static void main(String[] args) throws Exception
{
EventQueue.invokeLater( () -> createAndShowGUI() );
}
}
查看 工作线程和 Swing Worker 了解更多信息SwingWorker 的相关信息.
Check out Worker Threads and Swing Worker for more information about SwingWorker.
这篇关于冒泡排序动画的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
