HintTextField.java

package tk.amberide.ide.swing.textbox;

import javax.swing.*;
import javax.swing.text.JTextComponent;
import java.awt.*;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;

public class HintTextField extends JTextField implements FocusListener {

    private String hint;

    public HintTextField() {
        this("");
    }

    public HintTextField(final String hint) {
        setHint(hint);
        super.addFocusListener(this);
    }

    public void setHint(String hint) {
        this.hint = hint;
        setUI(new HintTextFieldUI(hint, true));
    }

    public void focusGained(FocusEvent e) {
        if (this.getText().length() == 0) {
            super.setText("");
        }
    }

    public void focusLost(FocusEvent e) {
        if (this.getText().length() == 0) {
            setHint(hint);
        }
    }

    public String getText() {
        String typed = super.getText();
        return typed.equals(hint) ? "" : typed;
    }
}

class HintTextFieldUI extends javax.swing.plaf.basic.BasicTextFieldUI implements FocusListener {

    private String hint;
    private boolean hideOnFocus;
    private Color color;

    public Color getColor() {
        return color;
    }

    public void setColor(Color color) {
        this.color = color;
        repaint();
    }

    private void repaint() {
        if (getComponent() != null) {
            getComponent().repaint();
        }
    }

    public boolean isHideOnFocus() {
        return hideOnFocus;
    }

    public void setHideOnFocus(boolean hideOnFocus) {
        this.hideOnFocus = hideOnFocus;
        repaint();
    }

    public String getHint() {
        return hint;
    }

    public void setHint(String hint) {
        this.hint = hint;
        repaint();
    }

    public HintTextFieldUI(String hint) {
        this(hint, false);
    }

    public HintTextFieldUI(String hint, boolean hideOnFocus) {
        this(hint, hideOnFocus, null);
    }

    public HintTextFieldUI(String hint, boolean hideOnFocus, Color color) {
        this.hint = hint;
        this.hideOnFocus = hideOnFocus;
        this.color = color;
    }

    protected void paintSafely(Graphics g) {
        super.paintSafely(g);
        JTextComponent comp = getComponent();
        if (hint != null && comp.getText().length() == 0 && (!(hideOnFocus && comp.hasFocus()))) {
            if (color != null) {
                g.setColor(color);
            } else {
                g.setColor(Color.gray);
            }
            int padding = (comp.getHeight() - comp.getFont().getSize()) / 2;
            g.drawString(hint, 5, comp.getHeight() - padding - 1);
        }
    }

    public void focusGained(FocusEvent e) {
        if (hideOnFocus) {
            repaint();
        }

    }

    public void focusLost(FocusEvent e) {
        if (hideOnFocus) {
            repaint();
        }
    }

    protected void installListeners() {
        super.installListeners();
        getComponent().addFocusListener(this);
    }

    protected void uninstallListeners() {
        super.uninstallListeners();
        getComponent().removeFocusListener(this);
    }
}