java - JTable 没有显示在 UI 中？

Question

我想在 UI 上创建一个示例表。但无论我尝试什么，它都没有显示出来。也许有人可以帮助我？

public void createGUI(){
        JFrame myframe = new JFrame("Frame");
        JButton firstButton = new JButton("Connect");


        myframe.setLayout(null);
        myframe.setVisible(true);
        myframe.setSize(500, 500);
        //myframe.add(firstButton);


        firstButton.addActionListener(new handler("ConnectButton"));
        firstButton.setSize(150, 100);
        firstButton.setLocation(100, 100);

        String[] columnNames = {"First Name",
                "Last Name",
                "Sport",
                "# of Years",
                "Vegetarian"};

        Object[][] data = {
                {"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)}
            };

        JTable table = new JTable(data, columnNames);
        table.setVisible(true);

        //JScrollPane scrollPane = new JScrollPane(table);
        //scrollPane.setVisible(true);
        table.setFillsViewportHeight(true);
        myframe.add(table);
    }

Answer 1

问题是当您在这一行中将布局设置为 null 时:

myframe.setLayout(null);

只需删除此行即可正常工作。因为布局设置为 null 时无法显示窗口。因此，一旦删除此行，将使用默认布局。

以下是您可能想阅读的有关布局管理器的更多信息:https://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html

我删除的第二件事是这一行:

table.setFillsViewportHeight(true);

您应该使用 myframe.pack(); 来代替，以便它打包框架上的所有组件。

所以我最终得到了:

public static void createGUI() {
        JFrame myframe = new JFrame("Frame");
        JButton firstButton = new JButton("Connect");

        myframe.setSize(500, 500);

        String[] columnNames = {"First Name",
            "Last Name",
            "Sport",
            "# of Years",
            "Vegetarian"};

        Object[][] data = {
            {"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)}
        };

        JTable table = new JTable(data, columnNames);
        table.setVisible(true);

        myframe.add(table);
        myframe.pack();           // added this
        myframe.setVisible(true); // and moved this from top
    }

所以最终结果如下所示: