java swing JTextField set PlaceHolder [duplicate]

问题

This question already has an answer here:

Java - placeholder on textfield 3 answers

I create a JTextField and now i want to set the placeholder on that JTextField i don\'t Know how to set the placeholder on the JTextField? Please Help How to set Placeholder text on JTextField

JTextField database=new JTextField(\"Enter Data Base Name\");
database.setPreferredSize(database.getPreferredSize());
database.setText(\"\");

That is my code to text field now in that code i want to set placeholder how to set a placeholder on that JTextField

回答1:

Try this class:

package playground;

import java.awt.*;

import javax.swing.*;
import javax.swing.text.Document;

@SuppressWarnings("serial")
public class PlaceholderTextField extends JTextField {

    public static void main(final String[] args) {
        final PlaceholderTextField tf = new PlaceholderTextField("");
        tf.setColumns(20);
        tf.setPlaceholder("All your base are belong to us!");
        final Font f = tf.getFont();
        tf.setFont(new Font(f.getName(), f.getStyle(), 30));
        JOptionPane.showMessageDialog(null, tf);
    }

    private String placeholder;

    public PlaceholderTextField() {
    }

    public PlaceholderTextField(
        final Document pDoc,
        final String pText,
        final int pColumns)
    {
        super(pDoc, pText, pColumns);
    }

    public PlaceholderTextField(final int pColumns) {
        super(pColumns);
    }

    public PlaceholderTextField(final String pText) {
        super(pText);
    }

    public PlaceholderTextField(final String pText, final int pColumns) {
        super(pText, pColumns);
    }

    public String getPlaceholder() {
        return placeholder;
    }

    @Override
    protected void paintComponent(final Graphics pG) {
        super.paintComponent(pG);

        if (placeholder == null || placeholder.length() == 0 || getText().length() > 0) {
            return;
        }

        final Graphics2D g = (Graphics2D) pG;
        g.setRenderingHint(
            RenderingHints.KEY_ANTIALIASING,
            RenderingHints.VALUE_ANTIALIAS_ON);
        g.setColor(getDisabledTextColor());
        g.drawString(placeholder, getInsets().left, pG.getFontMetrics()
            .getMaxAscent() + getInsets().top);
    }

    public void setPlaceholder(final String s) {
        placeholder = s;
    }

}

回答2:

JTextField searchText;

...

In constructor:

searchText = new JTextField("Search");
searchText.setForeground(Color.GRAY);
searchText.addFocusListener(new FocusListener() {
    @Override
    public void focusGained(FocusEvent e) {
        if (searchText.getText().equals("Search")) {
            searchText.setText("");
            searchText.setForeground(Color.BLACK);
        }
    }
    @Override
    public void focusLost(FocusEvent e) {
        if (searchText.getText().isEmpty()) {
            searchText.setForeground(Color.GRAY);
            searchText.setText("Search");
        }
    }
    });

回答3:

If I understand the question, Text Prompt shows one way you can do this.

回答4:

So simple use a swingx jar then like this

JTextArea txtMSISDNList = new JTextArea();  
PromptSupport.setPrompt("01197585960,01197585961", txtMSISDNList);

来源：https://stackoverflow.com/questions/16213836/java-swing-jtextfield-set-placeholder

标签

java

swing

jtextfield

placeholder