java - JPanel 中的 JTable 不显示

Question

我不明白问题出在哪里。 JTable 嵌入在 JScrollPanel 中，JScrollPanel 嵌入在 JPanel 中。该表未显示。任何帮助表示赞赏。我可能错过了添加一些元素。彻底检查但找不到任何东西。这只是构造函数:

    public TableIssues() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100, 100, 894, 597);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5, 5, 5, 5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        JPanel patientsPanel = new JPanel();
        patientsPanel.setBounds(6, 152, 882, 417);
        patientsPanel.setLayout(null);

        String[] patientsColumns = {
                "one", 
                "two",
                "three"};
        String[][] tableInput={{"first","second","third"},{"first","second","third"}};

        patientsTable = new JTable(tableInput,patientsColumns);
        JScrollPane scroll = new JScrollPane();
        scroll.setBounds(0, 0, 882, 363);
        scroll.setLayout(null);
        scroll.setViewportView(patientsTable);
        patientsPanel.add(scroll);

        JButton addPatietsButton = new JButton("Add");
        addPatietsButton.setFont(new Font("Lucida Grande", Font.PLAIN, 20));
        addPatietsButton.setBounds(356, 375, 211, 36);

        patientsPanel.add(addPatietsButton);
        contentPane.add(patientsPanel);

    }

Answer 1

永远不要这样做:

scroll.setLayout(null);

你破坏了 JScrollPane 的布局，因此它完全失去了它的功能，从而搬起石头砸自己的脚。删除该行。

虽然空布局和 setBounds() 对于 Swing 新手来说似乎是创建复杂 GUI 的最简单和最好的方法，但您创建的 Swing GUI 越多，使用它们时遇到的困难就越严重.当 GUI 调整大小时，它们不会调整组件的大小，它们是增强或维护的皇家女巫，当放置在滚动 Pane 中时它们会完全失败，当在所有平台或与原始屏幕分辨率不同的屏幕分辨率上查看时，它们看起来很糟糕.

比如这个GUI

由这段代码创建:

import java.awt.BorderLayout;
import java.awt.GridLayout;
import javax.swing.*;
import javax.swing.table.DefaultTableModel;

public class TableIssues2 extends JPanel {
    private static final int GAP = 5;
    private static final String[] COL_NAMES = {"One", "Two", "Three"};
    private DefaultTableModel model = new DefaultTableModel(COL_NAMES, 0);
    private JTable patientsTable = new JTable(model);

    public TableIssues2() {
        JPanel buttonPanel = new JPanel(new GridLayout(1, 0, GAP, GAP));
        buttonPanel.add(new JButton("Add"));
        buttonPanel.add(new JButton("Remove"));
        buttonPanel.add(new JButton("Exit"));

        JPanel bottomPanel = new JPanel();
        bottomPanel.add(buttonPanel);

        for (int i = 0; i < 5; i++) {
            model.addRow(new String[]{"First", "Second", "Third"});
        }
        setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
        setLayout(new BorderLayout(GAP, GAP));
        add(new JScrollPane(patientsTable), BorderLayout.CENTER);
        add(bottomPanel, BorderLayout.PAGE_END);
    }

    private static void createAndShowGui() {
        TableIssues2 mainPanel = new TableIssues2();

        JFrame frame = new JFrame("TableIssues2");
        frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        frame.getContentPane().add(mainPanel);
        frame.pack();
        frame.setLocationByPlatform(true);
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGui();
            }
        });
    }
}