在JSplitPane上设置分隔符位置不起作用

Question

我正在尝试设置JSplitPane的分隔符位置,但似乎无法正常工作.

这是一个SSCCE:

import java.awt.Color;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JSplitPane;


public class JSplitProblem extends JFrame {

    public JSplitProblem(){
        JPanel upperPanel = new JPanel();
        upperPanel.setLayout(new BoxLayout(upperPanel, BoxLayout.X_AXIS));

        JPanel leftPanel = new JPanel();

        leftPanel.setLayout(new BoxLayout(leftPanel, BoxLayout.Y_AXIS));
        JPanel red = new JPanel();
        red.setBackground(Color.red);
        leftPanel.add(red);

        JPanel rightPanel = new JPanel();
        rightPanel.setLayout(new BoxLayout(rightPanel, BoxLayout.Y_AXIS));
        JPanel blue = new JPanel();
        blue.setBackground(Color.blue);
        rightPanel.add(blue);

        upperPanel.add(leftPanel);
        upperPanel.add(rightPanel);
        JPanel bottomPanel = new JPanel();
        bottomPanel.setBackground(Color.black);

        JSplitPane mainSplittedPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT, upperPanel,bottomPanel);
        mainSplittedPane.setOneTouchExpandable(true);
        mainSplittedPane.setDividerLocation(0.5);

        this.add(mainSplittedPane);
        this.setSize(800,600);
        this.setResizable(true);
        this.setVisible(true);
    }

    public static void main(String[] args) {
        new JSplitProblem();
    }

}

我希望黑色底部面板默认位于整个区域的50%.我究竟做错了什么？

Answer 1

如果希望拆分窗格的两半在拆分窗格的额外或删除空间中共享,请将调整大小权重设置为0.5 :( 教程)

JSplitPane mainSplittedPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT, upperPanel,bottomPanel);
mainSplittedPane.setOneTouchExpandable(true);
mainSplittedPane.setResizeWeight(0.5);                            

Answer 2

在这种情况下,没有任何复杂的规则

1)PrefferedSize必须返回Childs而不是我错误设置在我的情况下:-),然后我的答案不是@kleopatra抵抗

2)把所有关于rezize,尺寸,等等的内容都JSplitPane放进去invokeLater() .

.

import java.awt.*;
import javax.swing.*;

public class JSplitProblem extends JFrame {

    private static final long serialVersionUID = 1L;
    private JSplitPane mainSplittedPane;

    public JSplitProblem() {
        JPanel upperPanel = new JPanel();
        upperPanel.setLayout(new BoxLayout(upperPanel, BoxLayout.X_AXIS));
        JPanel leftPanel = new JPanel();
        leftPanel.setLayout(new BoxLayout(leftPanel, BoxLayout.Y_AXIS));
        JPanel red = new JPanel();
        red.setBackground(Color.red);
        leftPanel.add(red);
        JPanel rightPanel = new JPanel();
        rightPanel.setLayout(new BoxLayout(rightPanel, BoxLayout.Y_AXIS));
        JPanel blue = new JPanel();
        blue.setBackground(Color.blue);
        rightPanel.add(blue);
        upperPanel.add(leftPanel);
        upperPanel.add(rightPanel);
        JPanel bottomPanel = new JPanel();
        bottomPanel.setBackground(Color.black);

        mainSplittedPane = new JSplitPane(JSplitPane.VERTICAL_SPLIT, upperPanel, bottomPanel);
        mainSplittedPane.setOneTouchExpandable(true);
        mainSplittedPane.setDividerLocation(0.5);

        add(mainSplittedPane);
        setPreferredSize(new Dimension(400, 300));
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        setResizable(true);
        setVisible(true);
        pack();
        restoreDefaults();
    }

    private void restoreDefaults() {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                mainSplittedPane.setDividerLocation(mainSplittedPane.getSize().height /2);
                //mainSplittedPane.setDividerLocation(mainSplittedPane.getSize().width /2);
            }
        });
    }

    public static void main(String[] args) {
        JSplitProblem jSplitProblem = new JSplitProblem();
    }
}