使用Java Swing绘制多行

Question

我正在学习使用Java Swing绘制线条以绘制迷宫.我可以在指定的位置绘制一条线,它显示得很好.但是当我想画多行时,只有最后一行显示.我的代码:

public class LabyrinthGUI extends JFrame {
...
Line line;
for (int i = 0; i < 10; i++) {
   line = new Line(i*25, 0, (i+1)*25, 50);
   this.getContentPane().add(line);
}
}

public class Line extends JPanel{
private int x1, y1, x2, y2;

public Line(int x1, int y1, int x2, int y2) {
    this.x1 = x1;
    this.y1 = y1;
    this.x2 = x2;
    this.y2 = y2;
}
public void paintComponent (Graphics g) {
    g.drawLine(x1, y1, x2, y2);

}

我可能需要刷新一些东西,以显示用for-loop绘制的所有线条,但不知道是什么.

Answer 1

为什么你的例子不起作用很简单; Swing使用布局管理器将添加到a的每个组件Container放到屏幕上.这样,线条不重叠.

相反,使用Component绘制每一行的一个.绘制迷宫的解决方案是:

public class Labyrinth extends JPanel {

    private final ArrayList<Line> lines = new ArrayList<Line>();

    public void addLine(int x1, int y1, int x2, int y2) {
        this.lines.add(new Line(x1, y1, x2, y2));
    }

    public void paintComponent(Graphics g) {
        for(final Line r : lines) {
            r.paint(g);
        }
    }
}

public static class Line {
    public final int x1;
    public final int x2;
    public final int y1;
    public final int y2;
    public Line(int x1, int y1, int x2, int y2) {
        this.x1 = x1;
        this.x2 = x2;
        this.y1 = y1;
        this.y2 = y2;
    }
    public void paint(Graphics g) {
        g.drawLine(this.x1, this.y1, this.x2, this.y2);
    }
}

然后用来Labyrinth.addLine为你的迷宫添加线条.也; Labyrinth通过调用setBounds或类似方式为您指定宽度和高度,因为Swing可能正在裁剪图形.