How can I control the width of JTextFields in Java Swing?

问题

I am trying to have several JTextFields on a single row, but I don't want them to have the same width. How can I control the width and make some of them wider than others? I want that they together take up 100% of the total width, so it would be good if I could use some kind of weigthing.

I have tried with .setColumns() but it doesn't make sense.

Here is an example, where I am using three rows with three strings that should appear as in columns:

import java.awt.GridLayout;
import javax.swing.BoxLayout;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;

public class RowTest extends JPanel {

    class Row extends JComponent {
        public Row(String str1, String str2, String str3) {
            this.setLayout(new BoxLayout(this, BoxLayout.X_AXIS));

            JTextField fld1 = new JTextField(str1);
            JTextField fld2 = new JTextField(str2);
            JTextField fld3 = new JTextField(str3);

            fld1.setColumns(5); // makes no sense

            this.add(fld1);
            this.add(fld2);
            this.add(fld3);
        }
    }

    public RowTest() {
    this.setLayout(new GridLayout(5,0));

    this.add(new Row("Short", "A long text that takes up more space",
        "Short again"));
    this.add(new Row("Longer but short", "Another long string", "Short"));
    this.add(new Row("Hello", "The long field again",
        "Some info"));
    }

    public static void main(String[] args) {
        new JFrame() {{ this.getContentPane().add(new RowTest());
                            this.pack(); this.setVisible(true); }};
    }

}

回答1:

All Swing components have a preferred size. The preferred size of a text component is based on the text of the component. So generally the component is painted at its preferred size.

So I don't see the problem with your code snippet. Each text field should have a different preferred size. Also, as the frame is resized the width will be adjusted since the BoxLayout will try to resize each component up to its maximum/minimum size.

If you need more help post your SSCCE that actually demonstrates the sizing problem you are experiencing.

Edit:

Based on the latest requirement you can use the Relative Layout.

回答2:

yourTextField = new JTextField("", 20);

if you start it like this it sets the textfield to be empty and to have 20 collumns

回答3:

Try this:

textfield.setPreferredSize(new Dimension(int width, int height));

回答4:

// 1. create JTextField
yourTextField = new JTextField();
// 2. store default height
int defaultHeight = yourTextField.getSize().getHeight();
// 3. set custom width and default height
yourTextField.setSize(new Dimension(yourWidth, defaultHeight));

来源：https://stackoverflow.com/questions/2897506/how-can-i-control-the-width-of-jtextfields-in-java-swing