我对 java 很好，也有很好的理解，但我坚持一个项目，我正在处理.. 我试图将 JTextField 移动到屏幕的左侧，但无论我尝试什么，它都保持在顶部居中..这是我的代码：
public class Display extends JFrame{
public static final int CANVAS_WIDTH = 1000;
public static final int CANVAS_HEIGHT = 450;
public static final Color LINE_COLOR = Color.BLACK;
public static final Color GROUND_COLOR = Color.GREEN;
public static final Color CANVAS_BACKGROUND = Color.CYAN;
public static final Color TRANS = Color.CYAN;
private int x1 = CANVAS_WIDTH / 2;
private int y1 = CANVAS_HEIGHT / 2;
private int x2 = CANVAS_WIDTH /2;
private int y2 = CANVAS_HEIGHT / 2;
private int Sx1 = CANVAS_WIDTH ;
private int Sy1 = CANVAS_HEIGHT ;
private int Sy2 = CANVAS_HEIGHT ;
private int Rx1 = CANVAS_WIDTH - CANVAS_WIDTH;
private int Ry1 = CANVAS_HEIGHT;
private int Rx2 = CANVAS_WIDTH;
private int Ry2 = CANVAS_HEIGHT ;
private int Lx1 = CANVAS_WIDTH / 2;
private int Ly1 = CANVAS_HEIGHT / 2;
private int Lx2 = CANVAS_WIDTH / 2;
private int Ly2 = CANVAS_HEIGHT / 2;
private int Mx1 = CANVAS_WIDTH / 2;
private int My1 = CANVAS_HEIGHT / 2;
private int Mx2 = CANVAS_WIDTH / 2;
private int My2 = CANVAS_HEIGHT / 2;
int[] xs = {380, 460, 460, 540, 540, 620, 500, 380};
int[] ys = {260, 260, 250, 250, 260, 260, 205, 260};
private DrawCanvas canvas;
private JTextField tfCount;
private int count = 0;
public class CountUpAction extends AbstractAction {
/** Constructor */
public CountUpAction(String name, String shortDesc, Integer mnemonic) {
super(name);
putValue(SHORT_DESCRIPTION, shortDesc);
putValue(MNEMONIC_KEY, KeyEvent.VK_NUMPAD4);
}
@Override
public void actionPerformed(ActionEvent e) {
addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent evt) {
switch(evt.getKeyCode()) {
case KeyEvent.VK_NUMPAD1:
//original count
count += 1;
tfCount.setText(count + "");
}
}
});
}
}
public class CountDownAction extends AbstractAction {
/** Constructor */
public CountDownAction(String name, String shortDesc, Integer mnemonic) {
super(name);
putValue(SHORT_DESCRIPTION, shortDesc);
putValue(MNEMONIC_KEY, KeyEvent.VK_NUMPAD5);
}
@Override
public void actionPerformed(ActionEvent e) {
addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent evt) {
switch(evt.getKeyCode()) {
case KeyEvent.VK_NUMPAD2:
//original count
count -= 1;
tfCount.setText(count + "");
}
}
});
}
}
public Display() {
canvas = new DrawCanvas();
canvas.setPreferredSize(new Dimension(CANVAS_WIDTH, CANVAS_HEIGHT));
Container cp = getContentPane();
cp.setLayout(new BorderLayout());
cp.add(canvas, BorderLayout.LINE_START);
// Create the Actions shared by the button and menu-item
Action countUpAction = new CountUpAction("Count Up",
"", new Integer(KeyEvent.VK_ENTER));
Action countDownAction = new CountDownAction("Count Down",
"", new Integer(KeyEvent.VK_D));
canvas.add(new JLabel("alt+4: activeate up"));
canvas.add(new JLabel("alt+5: activate down"));
tfCount = new JTextField("0", 8);
tfCount.setHorizontalAlignment(JTextField.CENTER);
tfCount.setEditable(false);
canvas.add(tfCount, BorderLayout.LINE_START);
//Invisible
JButton btnCountUp = new JButton();
btnCountUp.setFocusable(false);
btnCountUp.setHideActionText(true);
btnCountUp.setContentAreaFilled(false);
btnCountUp.setBorderPainted(false);
canvas.add(btnCountUp, DrawCanvas.LEFT_ALIGNMENT);
//Invisible
JButton btnCountDown = new JButton();
btnCountDown.setFocusable(false);
btnCountDown.setHideActionText(true);
btnCountDown.setContentAreaFilled(false);
btnCountDown.setBorderPainted(false);
canvas.add(btnCountDown);
// Set actions for buttons
btnCountUp.setAction(countUpAction);
btnCountDown.setAction(countDownAction);
addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent evt) {
switch(evt.getKeyCode()) {
case KeyEvent.VK_LEFT:
Rx1 -= 10; Ry1 += 10;
Rx2 += 10; Ry2 -= 10;
x1 -=10; x2 +=10;
Lx1 -= 10; Lx2 -= 10;
Mx1 += 10; Mx2 -= 10;
repaint();
break;
case KeyEvent.VK_RIGHT:
Rx1 -= 10; Ry1 -= 10;
Rx2 += 10; Ry2 += 10;
x1 += 10; x2 += 10;
Lx1 += 10; Lx2 += 10;
Mx1 -= 10; Mx2 += 10;
repaint();
break;
case KeyEvent.VK_DOWN:
y1 -= 10; y2 -= 10;
Ly1 -= 10; Ly2 -= 10;
Sy1 += 10; Sy2 -= 10;
Ry1 +=10; Ry2 += 10;
repaint();
break;
case KeyEvent.VK_UP:
y1 += 10; y2 += 10;
Ly1 += 10; Ly2 += 10;
Sy1 -= 10; Sy2 += 10;
Ry1 -= 10; Ry2 -= 10;
repaint();
break;
case KeyEvent.VK_M:
System.exit(0);
}
}
});
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setTitle("FLIGHT DISPLAY");
pack();
setVisible(true);
requestFocus();
}
class DrawCanvas extends JPanel {
public void paintComponent(Graphics g) {
super.paintComponent(g);
setBackground(CANVAS_BACKGROUND);
g.setColor(GROUND_COLOR);
//Draw ground Color
g.drawRect(Sx1 - Sx1,Sy1 /2, CANVAS_WIDTH, Sy2 /2);
g.fillRect(Sx1 - Sx1, Sy1 /2, CANVAS_WIDTH, Sy2 /2);
g.setColor(LINE_COLOR);
//Draw line centre horizontal
g.drawLine(Rx1, Ry1 /2, Rx2, Ry2 /2);
g.drawOval(x1 -15, y1 -15, 30, 30);
g.fillOval(x1 - 5, y1 -5, 10, 10);
//Draw line centre vertical
g.drawLine(Mx1, My1 + My1, Mx2, My2 - My2);
//Draw line dim
g.setColor(Color.YELLOW);
g.fillArc(300, 0, 400, 140, 0, 180);
g.setColor(LINE_COLOR);
g.drawLine(Lx1 -25, Ly1 +20, Lx2 +25, Ly2 +20);
g.drawLine(Lx1 -50, Ly1 +40, Lx2 +50, Ly2 +40);
g.drawLine(Lx1 -25, Ly1 +60, Lx2 +25, Ly2 +60);
g.drawLine(Lx1 -75, Ly1 +80, Lx2 +75, Ly2 +80);
g.drawLine(Lx1 -25, Ly1 +100, Lx2 +25, Ly2 +100);
//Draw line dim
g.drawLine(Lx1 -25, Ly1 -20, Lx2 +25, Ly2 -20);
g.drawLine(Lx1 -50, Ly1 -40, Lx2 +50, Ly2 -40);
g.drawLine(Lx1 -25, Ly1 -60, Lx2 +25, Ly2 -60);
g.drawLine(Lx1 -75, Ly1 -80, Lx2 +75, Ly2 -80);
g.drawLine(Lx1 -25, Ly1 -100, Lx2 +25, Ly2 -100);
//Draw polyline centre plane
g.drawPolyline(xs, ys, 8);
g.drawArc(300, 0, 400, 140, 0, 180);
g.drawLine(Mx1+30, My1 + My1, Mx2, My2 - My2);
g.drawLine(Mx1-30, My1 + My1, Mx2, My2 - My2);
g.drawString(Ccount, 100,100);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new Display();
}
});
}
}