JTable，为什么我的表没有按预期显示

Question

我第一次尝试学习一些JTable，我遇到的问题是我想要实现的目标。

最终我希望我的JTable位于边框布局的中间，列名显示在顶部，目前每个单元格都填充了单词“hey”。我还尝试在此表中添加一个空边框，以阻止表“拥抱”组件的边缘。

这是我目前的输出：

如您所见，我添加的边框显然没有显示，表格标题也没有显示。虽然细胞填充正确。

最终我想实现：

这是使用的代码：

import java.awt.BorderLayout;

import javax.swing.BorderFactory;
import javax.swing.JPanel;
import javax.swing.JTable;

public class Leaderboard extends JPanel{


    private final String[] columnNames = {"Name", "Score", "Length", "Time"}; 

    public String[][] data = new String[10][4];

    public JTable table;

    public Leaderboard(){

        this.setLayout(new BorderLayout());

        for(int i = 0; i < 10; i++){
            for(int j = 0; j < 4; j++){
                data[i][j] = "hey";

            }

        }

        table = new JTable(data, columnNames);
        table.setBorder(BorderFactory.createEmptyBorder(150, 100, 40 , 40));
        table.setEnabled(false);

        JScrollPane scrollPane = new JScrollPane(table);
        this.add(table.getTableHeader(), BorderLayout.CENTER);
        this.add(table, BorderLayout.CENTER);

        this.add(table, BorderLayout.CENTER);


    }

}

感谢。

Answer 1

问题是BorderLayout的中心元素扩展了。我建议在以下答案中使用GridBagLayout与GridBagConstraint或Box类似：

Alex B answered "How do I add a margin outside the border of a component in Swing?"

这是一个有效的解决方案（gist）：

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

/**
 * CenterBorderedJTable.java
 *
 * @author Marco
 * @since 2014-07-10
 */
public class CenterBorderedJTable {

    private static final String[] tableColumns = {"First Name", "Last Name", "Hobby", "Age", "Vegetarian?" };

    private static final Object[][] tableData = {
            {"Kathy", "Smith",
                    "Snowboarding", new Integer(5), new Boolean(false)},
            {"John", "Doe",
                    "Rowing", new Integer(3), new Boolean(true)},
            {"Sue", "Black",
                    "Knitting", new Integer(2), new Boolean(false)},
            {"Jane", "White",
                    "Speed reading", new Integer(20), new Boolean(true)},
            {"Joe", "Brown",
                    "Pool", new Integer(10), new Boolean(false)}
    };

    /**
     * Creates a GridBagConstraints with the specified vertical and horizontal margin.
     * @param verticalMargin    The vertical margin specifies how many pixels the top and bottom margins will be
     * @param horizontalMargin  The horizontal margin specifies how many pixels the left and right margins will be
     * @return                  A GridBagConstraints with the specified vertical and horizontal margin.
     */
    private static GridBagConstraints createGridBagConstaints(int verticalMargin, int horizontalMargin) {
        GridBagConstraints constraints = new GridBagConstraints();
        constraints.insets = new Insets(verticalMargin, horizontalMargin, verticalMargin, horizontalMargin);
        return constraints;
    }

    /**
     *  This boilerplate is from the Java tutorials:
     *  @see <a href="http://docs.oracle.com/javase/tutorial/uiswing/painting/step1.html">Creating the Demo Application</a>
     */
    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }

    /**
     *  This boilerplate is from the Java tutorials:
     *  @see <a href="http://docs.oracle.com/javase/tutorial/uiswing/painting/step1.html">Creating the Demo Application</a>
     */
    private static void createAndShowGUI() {

        JFrame f = new JFrame("Center Bordered JTable");
        f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);  // exit JVM when window is closed

        // GridBagLayout needed since we use GridBagConstraints to constrain the table
        f.setLayout(new GridBagLayout());

        // Create JTable with our sample data
        JTable table = new JTable(tableData, tableColumns);
        JScrollPane scrollPane = new JScrollPane(table);                    // Allow for scrolling if data is too long
        scrollPane.setBorder(BorderFactory.createLineBorder(Color.CYAN));   // CYAN for easy visibility
        table.setFillsViewportHeight(true);

        // Add the scrollPane with the specified constraints to the window
        f.add(scrollPane, createGridBagConstaints(50, 25));

        // Pack and show the user!
        f.pack();
        f.setVisible(true);
    }
}

Answer 2

答案是使用JScrollPane＆＃39>。

需要此代码才能实现我想要的目标：

    table = new JTable(data, columnNames);
    //stops a user editing it
    table.setEnabled(false);
    JScrollPane scrollPane = new JScrollPane(table);
    scrollPane.setBorder(BorderFactory.createEmptyBorder(150, 100, 40 , 40));
    this.add(scrollPane,BorderLayout.CENTER);