试试这个添加按钮一次的代码，而不是每次调用paint(). 请注意，如果您在网格外部（而不是在按钮上）单击，此源仍会引发 AIOOBE，但这似乎是一个基本逻辑错误，您应该在修复按钮后进行调查。
// <applet code='GameOfLifeApplet' width=580 height=650></applet>
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class GameOfLifeApplet extends Applet implements MouseListener,ActionListener
{
//the x and y coordinates to get the location of the clicked points
private int xCo, yCo;
private int diff_x, diff_y;
private GameOfLife game = new GameOfLife();
private Button nextButton = null;
public void init()
{
setLayout(null);
nextButton = new Button("Next Stage");
diff_x = diff_y = 600 / game.getGridSize();
nextButton.setLocation(250, 575);
nextButton.setSize(120, 30);
// add the button once only!
add(nextButton);
addMouseListener(this);
}
private void drawEmptyGrid(Graphics g)
{
g.setColor(Color.white);
g.fillRect(0,0,600,600);
g.setColor(Color.black);
for(int i=0;i<game.getGridSize();++i)
{
g.drawLine(0,i*diff_x,600,i*diff_x);
g.drawLine(i*diff_x,0,i*diff_x,600);
}
g.setColor(Color.white);
}
public void paint(Graphics g)
{
drawEmptyGrid(g);
g.setColor(Color.red);
for(int i=0;i<game.getGridSize();++i)
{
for(int j=0;j<game.getGridSize();++j)
{
if( game.grid[i][j] )
{
g.fillRect(i*diff_x,j*diff_y,diff_x,diff_y);
}
}
}
g.setColor(Color.white);
}
// This method will be called when the mouse has been clicked.
public void mouseClicked (MouseEvent me) {
// Save the coordinates of the click lke this.
xCo = me.getX();
yCo = me.getY();
int x_init = xCo / diff_x;
int y_init = yCo / diff_y;
System.out.println(x_init + "x" + y_init);
game.grid[x_init][y_init] = true;
//show the results of the click
repaint();
}
// This is called when the mous has been pressed
public void mousePressed (MouseEvent me) {}
// When it has been released
// not that a click also calls these Mouse-Pressed and Released.
// since they are empty nothing hapens here.
public void mouseReleased (MouseEvent me) {}
// This is executed when the mouse enters the applet. it will only
// be executed again when the mouse has left and then re-entered.
public void mouseEntered (MouseEvent me) {}
// When the Mouse leaves the applet.
public void mouseExited (MouseEvent me) {}
public void actionPerformed(ActionEvent evt)
{
// Here we will ask what component called this method
if (evt.getSource() == nextButton)
{
System.out.println("I got clicked!");
game.nextIteration();
repaint();
}
}
}
class GameOfLife
{
private final int GRID_SIZE = 64;
public boolean [][] grid = new boolean[GRID_SIZE][GRID_SIZE];
//default constructor
public GameOfLife()
{
for(int i=0;i<GRID_SIZE;++i)
{
for(int j=0;j<GRID_SIZE;++j)
{
grid[i][j] = false;
}
}
}
public int getGridSize()
{
return GRID_SIZE;
}
public int getLiveNeighbors(int i,int j)
{
int neighbors = 0;
for( int tmp_i = i-1; tmp_i <= i+1; ++tmp_i )
{
for( int tmp_j = j-1; tmp_j <= j+1; ++tmp_j )
{
if( tmp_i < 0 || tmp_i >= GRID_SIZE || tmp_j < 0 || tmp_j >= GRID_SIZE )
{}
else
{
if( grid[tmp_i][tmp_j] )
{
neighbors++;
}
}
}
}
return neighbors;
}
public void nextIteration()
{
boolean [][] newGrid = new boolean[GRID_SIZE][GRID_SIZE];
for(int i=0;i<GRID_SIZE;++i)
{
for(int j=0;j<GRID_SIZE;++j)
{
newGrid[i][j] = grid[i][j];
}
}
for( int i=0;i<GRID_SIZE;++i)
{
for( int j=0;j<GRID_SIZE;++j)
{
int my_neighbors = getLiveNeighbors(i,j);
if( !newGrid[i][j] && my_neighbors == 3)
{
grid[i][j] = true;
}
else if( newGrid[i][j] && ( my_neighbors == 2 || my_neighbors == 3 ) )
{
grid[i][j] = true;
}
else
{
grid[i][j] = false;
}
}
}
System.out.println("Change of assignment");
}
}
更多提示
- 在这个千年不要使用 AWT 组件，而是使用 Swing。
- 不要使用
null布局。自定义渲染区域不需要它，并且应该使用布局管理器调整按钮的大小和位置（可能有一个边框来填充它）。
更新
此代码实现了上面“使用布局”的第二条建议，但将其作为练习让读者将组件更新为可能在这个千年中使用的东西（即 Swing）。
从某种意义上说，“作弊”下方的源代码以自然大小显示了 GUI。这在小程序中很难做到，因为大小是由 HTML 设置的。但是将 GUI 放入基于 Swing 的程序JOptionPane中，只需几行代码，就可以将其放在屏幕上，压缩成自然大小。
这是它在“自然大小”下的样子（我玩了一些数字，以使 GUI 更小）。
// <applet code='GameOfLifeApplet' width=320 height=350></applet>
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class GameOfLifeApplet extends Applet implements ActionListener
{
private Button nextButton = null;
private Ecosystem ecosystem;
public void init()
{
add(getGui());
}
public Component getGui() {
Panel gui = new Panel(new BorderLayout(3,3));
ecosystem = new Ecosystem();
gui.add(ecosystem, BorderLayout.CENTER);
nextButton = new Button("Next Stage");
Panel p = new Panel(new FlowLayout());
p.add(nextButton);
gui.add(p, BorderLayout.SOUTH);
nextButton.addActionListener(this);
return gui;
}
public void actionPerformed(ActionEvent evt)
{
// Here we will ask what component called this method
if (evt.getSource() == nextButton)
{
System.out.println("I got clicked!");
ecosystem.nextIteration();
ecosystem.repaint();
}
}
public static void main(String[] args) {
GameOfLifeApplet gola = new GameOfLifeApplet();
// quick cheat to get it on-screen (packed).
javax.swing.JOptionPane.showMessageDialog(null,gola.getGui());
}
}
class Ecosystem extends Panel implements MouseListener {
private GameOfLife game = new GameOfLife();
//the x and y coordinates to get the location of the clicked points
private int xCo, yCo;
private int diff_x, diff_y;
private int size = 300;
Ecosystem() {
diff_x = diff_y = 600 / game.getGridSize();
setPreferredSize(new Dimension(size,size));
addMouseListener(this);
}
public void nextIteration() {
game.nextIteration();
}
private void drawEmptyGrid(Graphics g)
{
g.setColor(Color.white);
g.fillRect(0,0,size,size);
g.setColor(Color.black);
for(int i=0;i<game.getGridSize();++i)
{
g.drawLine(0,i*diff_x,size,i*diff_x);
g.drawLine(i*diff_x,0,i*diff_x,size);
}
g.setColor(Color.white);
}
public void paint(Graphics g)
{
drawEmptyGrid(g);
g.setColor(Color.red);
for(int i=0;i<game.getGridSize();++i)
{
for(int j=0;j<game.getGridSize();++j)
{
if( game.grid[i][j] )
{
g.fillRect(i*diff_x,j*diff_y,diff_x,diff_y);
}
}
}
g.setColor(Color.white);
}
// This method will be called when the mouse has been clicked.
public void mouseClicked (MouseEvent me) {
Point point = me.getPoint();
// Save the coordinates of the click lke this.
xCo = (int)point.getX();
yCo = (int)point.getY();
int x_init = xCo / diff_x;
int y_init = yCo / diff_y;
System.out.println(x_init + "x" + y_init);
game.grid[x_init][y_init] = true;
//show the results of the click
repaint();
}
// This is called when the mous has been pressed
public void mousePressed (MouseEvent me) {}
// When it has been released
// not that a click also calls these Mouse-Pressed and Released.
// since they are empty nothing hapens here.
public void mouseReleased (MouseEvent me) {}
// This is executed when the mouse enters the applet. it will only
// be executed again when the mouse has left and then re-entered.
public void mouseEntered (MouseEvent me) {}
// When the Mouse leaves the applet.
public void mouseExited (MouseEvent me) {}
}
class GameOfLife
{
private final int GRID_SIZE = 60;
public boolean [][] grid = new boolean[GRID_SIZE][GRID_SIZE];
//default constructor
public GameOfLife()
{
for(int i=0;i<GRID_SIZE;++i)
{
for(int j=0;j<GRID_SIZE;++j)
{
grid[i][j] = false;
}
}
}
public int getGridSize()
{
return GRID_SIZE;
}
public int getLiveNeighbors(int i,int j)
{
int neighbors = 0;
for( int tmp_i = i-1; tmp_i <= i+1; ++tmp_i )
{
for( int tmp_j = j-1; tmp_j <= j+1; ++tmp_j )
{
if( tmp_i < 0 || tmp_i >= GRID_SIZE || tmp_j < 0 || tmp_j >= GRID_SIZE )
{}
else
{
if( grid[tmp_i][tmp_j] )
{
neighbors++;
}
}
}
}
return neighbors;
}
public void nextIteration()
{
boolean [][] newGrid = new boolean[GRID_SIZE][GRID_SIZE];
for(int i=0;i<GRID_SIZE;++i)
{
for(int j=0;j<GRID_SIZE;++j)
{
newGrid[i][j] = grid[i][j];
}
}
for( int i=0;i<GRID_SIZE;++i)
{
for( int j=0;j<GRID_SIZE;++j)
{
int my_neighbors = getLiveNeighbors(i,j);
if( !newGrid[i][j] && my_neighbors == 3)
{
grid[i][j] = true;
}
else if( newGrid[i][j] && ( my_neighbors == 2 || my_neighbors == 3 ) )
{
grid[i][j] = true;
}
else
{
grid[i][j] = false;
}
}
}
System.out.println("Change of assignment");
}
}
其他事项
- 该代码将自定义绘画移动到
Panel. 这解决了直接绘制到顶级容器的常见问题。它还允许在不同的容器中轻松地重复使用相同的 GUI。在这种情况下，一个小程序和“应用程序”（通常放在一个框架中），一个JOptionPane. 它现在被称为“混合小程序/应用程序”（更易于测试）。
- 自定义绘制组件
Ecosystem（耸肩）通知布局它喜欢的大小。这有助于我们避免需要设置任何东西的大小或边界。
- 该按钮将与需要的一样大。