单击按钮后将对象添加到JPanel [英] Add Object to JPanel after button click

问题描述

我创建了一个内部带有JPanel的JScrollPane，我想在按下按钮后添加JPanel/JLabel/Other对象.例如，在按下三个按钮之后，我想要得到类似以下内容的东西:

I have created a JScrollPane with a JPanel inside it and I want to add JPanel/JLabel/Other objects after pressing the button. For example after three button presses I want to get something like this:

我尝试将myJPane.add(testLabel)与testlabel.setBounds()一起使用，但是没有结果，由于大小不变，我不想使用GridLayout.我希望添加的对象具有不同的大小-调整为文本内容.

I tried myJPane.add(testLabel) with testlabel.setBounds()but no result, I don't want to use GridLayout because of the unchangeable sizes. I would like it if the added objects had different sizes - adjusted to the text content.

我应该使用它什么以及如何使用?

What should I use for it and how?

先谢谢了. 最好的祝福， 汤姆.

Thanks in advance. Best regards, Tom.

推荐答案

这是JScrollPane内的JPanel，当按下按钮时会在其中添加JLabel:

Here is a JPanel inside a JScrollPane that adds JLabels to it when pressing the button:

public class Example extends JFrame {

    public Example() {

        JPanel boxPanel = new JPanel();
        boxPanel.setLayout(new BoxLayout(boxPanel, BoxLayout.PAGE_AXIS));

        JTextField textField = new JTextField(20);      
        JButton sendButton = new JButton("Send");
        sendButton.addActionListener(new ActionListener() {

            @Override
            public void actionPerformed(ActionEvent e) {

                JLabel label = new JLabel(textField.getText());
                label.setOpaque(true);
                label.setBackground(Color.RED);
                boxPanel.add(label);
                boxPanel.add(Box.createRigidArea(new Dimension(0,5)));
                textField.setText("");
                boxPanel.revalidate();
//              pack();
            }
        });


        JPanel southPanel = new JPanel();
        southPanel.add(textField);
        southPanel.add(sendButton);

        add(new JScrollPane(boxPanel));
        add(southPanel, BorderLayout.PAGE_END);

        setDefaultCloseOperation(EXIT_ON_CLOSE);
        pack();
        setLocationRelativeTo(null);
        setVisible(true);
    }

    public static void main(String[] args) {

        new Example();
    }
}

BoxLayout将标签堆叠在一起.

注释:

必须在label上调用
• setOpaque(true)才能使用背景色.
• Box.createRigidArea用于创建间隙.随心所欲地使用它.
• 必须立即调用revalidate()，以便立即显示新组件.
• 每次调用pack()(在JFrame上)都会调整其大小，以适应所有新组件.我只是将其放在此处进行演示，因为初始帧大小太小，无法显示添加的初始组件.

• setOpaque(true) must be called on label for it to honor the background color.
• Box.createRigidArea is used for creating gaps. Use it as you wish.
• The call to revalidate() is imperative in order to display the new components immediately.
• Calling pack() (on the JFrame) will resize it each time to fit all the new components. I just put it there for demonstration since the initial frame size is too small to display the initial components added.

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