Question

一些背景：我正在制作一个程序，它使用一个充满各种类型节点的JTree。 TreeSelectionListener确定它是什么类型的节点，清除组件的内部JPanel，然后将相应的JPanel添加到它刚刚清除的JPanel，以编辑特定于该类型节点的属性。 JPanel使用GridBagLayout，但文本字段没有正确显示（注意：标题是JTextField，描述是JTextArea： The JPanel

JPanel的代码如下：

class nodePanel extends JPanel{
        public nodePanel(DefaultMutableTreeNode info){
            super(new GridBagLayout());

            GridBagConstraints c = new GridBagConstraints();
            c.insets=new Insets(10,10,10,10);
            c.gridx=0;
            c.gridy=0;
            c.gridheight=1;
            c.gridwidth=1;
            c.weightx=0;
            c.weighty=0;

            c.fill=GridBagConstraints.NONE;
            c.anchor=GridBagConstraints.EAST;
            this.add(new JLabel("Title: "),c);

            c.gridy=1;
            c.weighty=2;
            c.gridheight=2;
            this.add(new JLabel("Description: "),c);

            c.gridx=1;
            c.gridy=0;
            c.gridheight=1;
            c.gridwidth=2;
            c.weightx=100;
            c.weighty=0;
            c.anchor=GridBagConstraints.WEST;
            c.fill=GridBagConstraints.HORIZONTAL;
            JTextField title = new JTextField();
            title.setMinimumSize(new Dimension(300,25));
            this.add(title,c);

            c.gridy=1;
            c.gridheight=2;
            c.weighty=200;
            JTextArea description = new JTextArea();
            JScrollPane descriptionScroll= new JScrollPane(description);
            descriptionScroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
            descriptionScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_NEVER);
            this.add(descriptionScroll, c);
        }
}

谢谢

Answer 1

// ..
JTextField title = new JTextField(20);  // suggest a size in columns!
//title.setMinimumSize(new Dimension(300,25)); // don't call these methods! (1)
this.add(title,c);

c.gridy=1;
c.gridheight=2;
c.weighty=200;
JTextArea description = new JTextArea(3, 15); // suggest a size in rows/cols!
// ..

请参阅Should I avoid the use of set(Preferred|Maximum|Minimum)Size methods in Java Swing?（是）。

Answer 2

好吧，问题不在于JPanel本身 - 封闭的JPanel有Gridbag，但没有设置重量或任何尺寸。猜猜它表明问题是你最不期望的地方。

Answer 3

它，是因为你没有给它长度。如果你在其中添加长度它将工作正常。用这个代替你的代码

JTextField title = new JTextField(10);

JTextArea description = new JTextArea(2,10);

Answer 4

class nodePanel extends JPanel{
        public nodePanel(DefaultMutableTreeNode info){
            super(new GridBagLayout());

            GridBagConstraints c = new GridBagConstraints();
            c.insets=new Insets(10,10,10,10);
            c.gridx=0;
            c.gridy=0;
            c.gridheight=1;
            c.gridwidth=1;
            c.weightx=0;
            c.weighty=0;
            c.fill=GridBagConstraints.NONE;
            c.anchor=GridBagConstraints.EAST;
            this.add(new JLabel("Title: "),c);

            c.gridy=1;
            c.weighty=2;
            c.gridheight=2;
            this.add(new JLabel("Description: "),c);

            c.gridx=1;
            c.gridy=0;
            c.ipadx=20;
            c.gridheight=1;
            c.gridwidth=2;
            c.weightx=100;
            c.weighty=0;
            c.anchor=GridBagConstraints.WEST;
            c.fill=GridBagConstraints.HORIZONTAL;
            JTextField title = new JTextField(10);
            title.setMinimumSize(new Dimension(300,25));
            this.add(title,c);

            c.gridy=1;
            c.gridheight=2;
            c.ipadx=20;
            c.ipady=5;
            c.weighty=200;
            JTextArea description = new JTextArea(5,2);
            JScrollPane descriptionScroll= new JScrollPane(description);
            descriptionScroll.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
            descriptionScroll.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_NEVER);
            this.add(descriptionScroll, c);
        }
}

使用此代码我改变了你的代码。你没有使用c.ipadx我添加这个字段，它应该可以工作。

GridBagLayout将JTextField和JTextArea显示为短的垂直线

4 个答案: