自动调整 GridBagLayout 中的组件大小

Question

在这段代码中，我使用了GridBagLayout布局管理器来放置一个面板，它包含一个JLabel和一个JTextField。

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

public class Simple
{
    JFrame simpleWindow = new JFrame("Simple MCVE");

    JPanel  simplePanel = new JPanel();

    JLabel lblSimple;
    JTextField txtSimple;

    public void numberConvertGUI()
    {
        simpleWindow.setBounds(10, 10, 420, 80);

        simpleWindow.setMinimumSize(new Dimension(420, 80));

        simpleWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        simpleWindow.setLayout(new GridLayout(1,1));

        createSimplePanel();

        simpleWindow.getContentPane().add(simplePanel);

        simpleWindow.setVisible(true);
    }

    public void createSimplePanel()
    {
        simplePanel.setLayout(new GridBagLayout());
        GridBagConstraints c = new GridBagConstraints();

        lblSimple = new JLabel();
        c.weightx = 0.0;
        c.weighty = 1.0;
        c.fill = GridBagConstraints.BOTH;
        c.insets = new Insets(0,2,0,2);
        c.gridx = 0;
        c.gridy = 0;
        c.ipady = 0;
        lblSimple.setText("Next to me is a JTextField: ");
        lblSimple.setHorizontalAlignment(JLabel.RIGHT);
        simplePanel.add(lblSimple, c);

        txtSimple = new JTextField();
        c.weightx = 0.5;
        c.fill = GridBagConstraints.HORIZONTAL;
        c.ipady = 5;
        c.gridx = 1;
        c.gridy = 0;
        c.insets = new Insets(0,2,0,2);
        simplePanel.add(txtSimple, c);
    }

    public static void main(String[] args)
    {
        Simple s = new Simple();
        s.numberConvertGUI();
    }
}

我希望能够根据输入的数据量自动调整文本字段的大小。例如，当在JTextField中输入字符串"How do I re-size this component automatically when the edge of it is reached?"时，它看起来像这样。

但是，当我输入字符串时，我希望JTextBox和JFrame可以自动调整大小，以产生类似于以下内容的东西。

唯一的问题是我不知道有什么可以让我这样做。我非常感谢任何帮助我完成此任务的帮助。

编辑

当组件自动重新调整大小时，我还希望该组件有一个最大尺寸。这样，随着更多数据的输入，组件不会超出某人的电脑监视器。

- Dan

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将DocumentListener添加到JTextField中，以计算JTextField中的字符串长度或列数，以便获取JTextField的PreferredSize或Dimension，然后调用revalidate和repaint到JFrame（也许这两个通知器必须包装在invokeLater中）。 - mKorbel

Answer 1

将我的布局更改为MigLayout后，我成功地让我的代码实现了我想要的功能。对于任何阅读此内容并对如何执行此操作感兴趣的人，请参见下面的代码。

import java.awt.*;
import javax.swing.*;
import java.lang.Object.*;
import javax.swing.event.*;
import javax.swing.text.*;
import net.miginfocom.swing.MigLayout;

public class Simple
{
    JFrame simpleWindow = new JFrame("Simple MCVE");

    JPanel  simplePanel = new JPanel();

    JLabel lblTitle;
    JLabel lblSimple;
    JTextField txtSimple;

    GraphicsEnvironment ge = GraphicsEnvironment.getLocalGraphicsEnvironment();
    String []fontFamilies = ge.getAvailableFontFamilyNames();

    int adv;
    int widthOftxtSimple;
    int i;
    int xDimension;

    public static int GetScreenWorkingWidth() 
    {
        return java.awt.GraphicsEnvironment.getLocalGraphicsEnvironment().getMaximumWindowBounds().width;
    }

    int maxSize = GetScreenWorkingWidth()-50;

    public void numberConvertGUI()
    {
        simpleWindow.setBounds(10, 10, 800, 100);

        simpleWindow.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        simpleWindow.setResizable(false);

        simpleWindow.setLayout(new GridLayout(1,1));

        createSimplePanel();

        simpleWindow.getContentPane().add(simplePanel);

        simpleWindow.setVisible(true);
    }

    public void createSimplePanel()
    {
        MigLayout layout = new MigLayout("" , "[][grow]");
        simplePanel.setLayout(layout);

        lblTitle = new JLabel();
        lblTitle.setText("This is a Title");
        simplePanel.add(lblTitle, "wrap, align center,span 2");

        lblSimple = new JLabel();
        lblSimple.setText("Next to me is a JTextField: ");
        simplePanel.add(lblSimple);

        String sMPMConstraints = "width 615::"+maxSize;
        txtSimple = new JTextField();
        simplePanel.add(txtSimple, "grow, "+sMPMConstraints);

        myDocumentListener();
    }

    public void myDocumentListener()
    {
        Document doc = txtSimple.getDocument(); 
        DocumentListener listener = new DocumentListener()
        {
            @Override
            public void insertUpdate(DocumentEvent e)
            {
                System.out.println("Insert");
                String simpleString = txtSimple.getText();
                Graphics graphics = txtSimple.getGraphics();
                Font test = txtSimple.getFont();
                FontMetrics metrics = graphics.getFontMetrics(test);
                adv = metrics.stringWidth(simpleString);
                System.out.println("The width of the string is: "+adv);
                widthOftxtSimple = txtSimple.getWidth();
                System.out.println("The width of the JTextField is: "+widthOftxtSimple);
                if(xDimension<maxSize)
                {
                    System.out.println("The x dimension is shorter than the max size which is: "+maxSize);
                    if(widthOftxtSimple-20<adv)
                    {
                        i = 615-20-adv; //615 in this case is the original length of the text box
                        //change for different text boxes
                        System.out.println("Value of i is: "+i);
                        xDimension = 800-i;
                        System.out.println("Value of xDimension is: "+xDimension);
                        simpleWindow.setBounds(10, 10, xDimension, 100);
                    }
                }

                else
                {
                    System.out.println("The x dimension is longer than the max size which is: "+maxSize);
                    simpleWindow.setBounds(10, 10, maxSize, 100);
                    String lastCharSize = simpleString.charAt(simpleString.length() - 1)+"";
                    int adv2 = metrics.stringWidth(lastCharSize);
                    xDimension = xDimension+adv2;
                }
            }

            @Override
            public void removeUpdate(DocumentEvent e)
            {
                System.out.println("Remove");
                String simpleString = txtSimple.getText();
                Graphics graphics = txtSimple.getGraphics();
                Font test = txtSimple.getFont();
                FontMetrics metrics = graphics.getFontMetrics(test);
                widthOftxtSimple = txtSimple.getWidth();
                System.out.println("The width of the JTextField is: "+widthOftxtSimple);
                System.out.println("Value of xDimension is: "+xDimension);
                if(xDimension<maxSize)
                {
                    if(xDimension>800) //Original length of the JFrame
                    {
                        System.out.println("last char = " + simpleString.charAt(simpleString.length() - 1));
                        String lastCharSize = simpleString.charAt(simpleString.length() - 1)+"";
                        int adv2 = metrics.stringWidth(lastCharSize);
                        int newX = xDimension-adv2;
                        simpleWindow.setBounds(10, 10, newX, 100);
                        xDimension = newX;
                        if(xDimension<800)
                        {
                            simpleWindow.setBounds(10, 10, 800, 100);
                        }
                    }
                }

                else
                {
                    System.out.println("last char = " + simpleString.charAt(simpleString.length() - 1));
                    String lastCharSize = simpleString.charAt(simpleString.length() - 1)+"";
                    int adv2 = metrics.stringWidth(lastCharSize);
                    int new3 = xDimension-adv2;
                    System.out.println("This is the else statement");
                    System.out.println("The new `xDimension` will be:"+ new3);
                    xDimension = new3;
                }
            }

            @Override
            public void changedUpdate(DocumentEvent e)
            {
                System.out.println("Change");
            }
        };
        doc.addDocumentListener(listener);
    }

    public static void main(String[] args)
    {
        Simple s = new Simple();
        s.numberConvertGUI();
    }
}

要想编译此程序而不出现错误，您需要下载MigLayout包。

- Dan

Answer 2

Swing中没有内置的功能来实现此操作。

您需要在文本字段后面添加一个DocumentListener，并在添加或删除文本时得到通知。

然后，您需要计算出您想要为文本字段设置的新大小（这本身可能很棘手 - 您可能需要使用FontMetrics），并重新调整控件大小以匹配。您可以通过查看重新调整大小与您希望允许的最大大小进行比较，轻松实现此时可以实现的最大大小。

有关DocumentListener的信息，请参见此处： https://docs.oracle.com/javase/tutorial/uiswing/events/documentlistener.html

有关FontMetrics的信息，请参见此处： https://docs.oracle.com/javase/tutorial/2d/text/measuringtext.html

- Tim B

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谢谢您，我已经使用字体度量和文档监听器使其正常工作。 - Dan