java - 将 JPanel 构造函数添加到 JPanel 显示灰色

Question

对 Java(以及一般编程)非常陌生我正在尝试设置此布局，并尝试基于以下开关构建 JPanel:

public class PrimaryDisplay extends JPanel {
private static final long serialVersionUID = 1L;
private int option = 0;

public int getOption() {
    return option;
}

public void setOption(int option) {
    this.option = option;
}

public PrimaryDisplay(int primaryChoice)  {
    setOption(primaryChoice);

    switch (getOption()) {
        case 1: //fixate
            //JPanel primaryScreen = new JPanel();
            //primaryScreen.setBackground(Color.BLUE);
            //primaryScreen.setLayout(new GridLayout(1,1));
            JLabel fixate = new JLabel();
            fixate.setText("+");
            fixate.setFont(new Font("Verdana", 1, 50));
            fixate.setForeground(Color.WHITE);
            fixate.setHorizontalAlignment(SwingConstants.CENTER);
            fixate.setVerticalAlignment(SwingConstants.CENTER);
            //.add(fixate);
            break;

        case 2: //

    }
}
}

并从 main 调用该构造函数:

import java.awt.Color;
import java.awt.Dimension;
import java.awt.Frame;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Toolkit;

import javax.swing.JFrame;
import javax.swing.JPanel;


public class Main {
public static JFrame fullFrame = new JFrame();
public static JPanel primaryContainer = new JPanel();
public static JPanel hmdContainer = new JPanel();
static Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
static int width = (int) screenSize.getWidth();
static int height = (int) screenSize.getHeight();
public static int primaryChoice = 1;

public static void main(String[] args) {
    fullFrame.setExtendedState(Frame.MAXIMIZED_BOTH);
    fullFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    fullFrame.setUndecorated(true);
    fullFrame.setLayout(new GridBagLayout());

    primaryContainer.setLayout(new GridLayout(2,1));
    primaryContainer.setBackground(Color.YELLOW);

    hmdContainer.setBackground(Color.GREEN);
    hmdContainer.setLayout(new GridLayout(3,1));

    JPanel filler = new JPanel();
    filler.setBackground(Color.RED);
    primaryContainer.add(filler);

    PrimaryDisplay prim = new PrimaryDisplay(primaryChoice);        
    primaryContainer.add(prim);

    HMD hmdDisplay = new HMD();
    hmdDisplay.setBackground(Color.ORANGE);
    hmdContainer.add(hmdDisplay);

    GridBagConstraints m = new GridBagConstraints();
    m.fill = GridBagConstraints.BOTH;
    m.gridwidth = 1;
    m.gridheight = 1;
    m.weightx = .7;
    m.weighty = 1;
    m.gridx = 0;
    m.gridy = 0;
    fullFrame.add(primaryContainer, m);
    m.gridy = 0;
    m.gridx = 1;
    m.weightx = .3;
    fullFrame.add(hmdContainer, m);     
    fullFrame.setVisible(true);

}

}

它只显示为灰色框......？可能非常简单的解决方案，但我现在很困惑。

谢谢。

Answer 1

我“相信”这就是您想要实现的目标......

“+”面板呈灰色的主要原因是，默认情况下 JPanel 是不透明的，因此它覆盖了其后面的所有内容...

如果您将PrimaryDisplay中的opaque属性更改为false，它将变得透明，允许父容器透过...

public PrimaryDisplay(int primaryChoice) {
    setOpaque(false);