java - 缩小 JFrame 不起作用

Question

我有一个 JFrame 和一些子 JPanel 对象。当我调整 JFrame 的大小并使其变大时，一切正常，并且子面板的大小调整正确。但是，如果我缩小 JFrame，面板将保持不变，并且会被裁剪。无论我使用什么布局，都会发生这种情况。

我知道我可以使用 EventListener 并手动设置大小，但我的问题是:为什么会发生这种情况？为什么放大时效果很好，缩小时却不好？我可以在没有 EventListener 的情况下解决它吗(可能是一些配置问题)？

我正在使用 Netbeans 7.3，以防相关。

====编辑====

在尝试获取一个最小的示例时，我意识到问题是我试图添加的组件之一，它是由我制作的。它是一个扩展 java.awt.Canvas 并绘制 VolleyBall 球场的对象。

但是，我一直无法找出为什么它不能正常收缩。代码如下:

import java.awt.*;
import java.util.Arrays;
import javax.print.attribute.standard.OrientationRequested;

public class CourtCanvas extends Canvas {
    private int courtHeight = 100;
    private int courtWidth = 200;
    private int left = 10;
    private int top = 10;
    private Point center = new Point();

    private Color bgColor = new Color(52, 153, 204);
    private Color lineColor = new Color(255, 255, 255);
    private Color floorColor = new Color(255, 153, 0);

    private OrientationRequested orientation;

    public CourtCanvas() {
        calcDimensions();
        setBackground(bgColor);

        for (int i = 0; i < localCoords.length; i++) {
            localCoords[i] = new Point();
            visitCoords[i] = new Point();
        }
    }

    private void calcDimensions() {
        if (this.getHeight() > this.getWidth()) {
            orientation = OrientationRequested.PORTRAIT;
            courtHeight = (int) Math.min(this.getHeight() * 0.9, this.getWidth() * 1.8);
            courtWidth = (int) (courtHeight / 2.0);
        }
        else {
            orientation = OrientationRequested.LANDSCAPE;
            courtWidth = (int) Math.min(this.getWidth()* 0.9, this.getHeight() * 1.8);
            courtHeight = (int) (courtWidth / 2.0);

        }

        center.x = (int) (getWidth() / 2.0);
        center.y = (int) (getHeight() / 2.0);

        left = (int) (center.x - courtWidth / 2.0);
        top = (int) (center.y - courtHeight / 2.0);
    }

    @Override
    public void paint(Graphics g) {
        setBackground(bgColor);
        calcDimensions();

        drawFloor(g);
        drawLines(g);
    }

    private void drawFloor(Graphics g) {
        g.setColor(floorColor);
        g.fillRect(left, top, courtWidth, courtHeight);
    }

    private void drawLines(Graphics g) {
        if (orientation == OrientationRequested.PORTRAIT) {
            drawLines_Portrait(g);
        }
        else {
            drawLines_Landscape(g);
        }
    }

    private void drawLines_Portrait(Graphics g) {
        g.setColor(lineColor);

        // perimeter
        g.drawRect(left, top, courtWidth, courtHeight);

        // center line
        g.drawLine(left, center.y, left + courtWidth, center.y);

        // local attack line
        g.drawLine(left, center.y + courtHeight / 6, left + courtWidth, center.y + courtHeight / 6);

        // visitor attack line
        g.drawLine(left, center.y - courtHeight / 6, left + courtWidth, center.y - courtHeight / 6);
    }

    private void drawLines_Landscape(Graphics g) {
        g.setColor(lineColor);

        // perimeter
        g.drawRect(left, top, courtWidth, courtHeight);

        // center line
        g.drawLine(center.x, top, center.x, top + courtHeight);

        // local attack line
        g.drawLine(center.x - courtWidth / 6, top, center.x - courtWidth / 6, top + courtHeight);

        // visitor attack line
        g.drawLine(center.x + courtWidth / 6, top, center.x + courtWidth / 6, top + courtHeight);
    }

}

Answer 1

导致所描述的行为的原因可能有很多。 例如，为面板设置的最小尺寸。

最适合您的是 Java 布局管理器。 教程:http://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html