关于Java + Swing 输入提示问题，麻烦大神们帮忙看看

Question

想做一个小软件，查询电话的，当输入号码时，自动在数据库中找到与之相匹配的，出现在下拉框选项里... ....Java + Swing 麻烦哪位大神给段代码

Answer 1

1. 来看看这个： 这是不是很难给它自己，顺便说一句.a对夫妇的监听器和自定义渲染，瞧的。
2. 你可以创建自己的：import java.awt.*;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.*;
public class Main {
public static void main(String[] args) {
final JFrame frame = new JFrame();
frame.setLayout(new BorderLayout());
final JTextField textFieldA = new HintTextField("A hint here");
final JTextField textFieldB = new HintTextField("Another hint here");
frame.add(textFieldA, BorderLayout.NORTH);
frame.add(textFieldB, BorderLayout.CENTER);
JButton btnGetText = new JButton("Get text");
btnGetText.addActionListener(new ActionListener() {
@Override
public void actionPerformed(ActionEvent e) {
String message = String.format("textFieldA='%s', textFieldB='%s'",
textFieldA.getText(), textFieldB.getText());
JOptionPane.showMessageDialog(frame, message);
}
});
frame.add(btnGetText, BorderLayout.SOUTH);
frame.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
frame.setVisible(true);
frame.pack();
}
}
class HintTextField extends JTextField implements FocusListener {
private final String hint;
private boolean showingHint;
public HintTextField(final String hint) {
super(hint);
this.hint = hint;
this.showingHint = true;
super.addFocusListener(this);
}
@Override
public void focusGained(FocusEvent e) {
if(this.getText().isEmpty()) {
super.setText("");
showingHint = false;
}
}
@Override
public void focusLost(FocusEvent e) {
if(this.getText().isEmpty()) {
super.setText(hint);
showingHint = true;
}
}
@Override
public String getText() {
return showingHint ? "" : super.getText();
}
}

如果你仍然在Java 1.5中，替换this.getText().isEmpty()同this.getText().length() == 0。
3. 下面是一个类的复制/粘贴的解决方案：import java.awt.Color;
import java.awt.Graphics;
import java.awt.event.FocusEvent;
import java.awt.event.FocusListener;
import javax.swing.plaf.basic.BasicTextFieldUI;
import javax.swing.text.JTextComponent;

public class HintTextFieldUI extends 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;
}
@Override
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(comp.getForeground().brighter().brighter().brighter());
}
int padding = (comp.getHeight() - comp.getFont().getSize())/2;
g.drawString(hint, 2, comp.getHeight()-padding-1);
}
}
@Override
public void focusGained(FocusEvent e) {
if(hideOnFocus) repaint();
}
@Override
public void focusLost(FocusEvent e) {
if(hideOnFocus) repaint();
}
@Override
protected void installListeners() {
super.installListeners();
getComponent().addFocusListener(this);
}
@Override
protected void uninstallListeners() {
super.uninstallListeners();
getComponent().removeFocusListener(this);
}
}

像这样使用它：TextField field = new JTextField();
field.setUI(new HintTextFieldUI("Search", true));

请注意，它是发生在protected void paintSafely(Graphics g)。
4. 对于任何（也就是，任何一个扩展JComponent的），你可以调用的setToolTipText（String）方法。 参考以下链接： 为的setToolTipText API “如何使用工具提示”教程
5. 如果您仍然寻找一个解决方案 CodeGo.net，这里有一个其他的答案（巴特Kiers和culmat），供大家参考：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));
//setText(this.hint);
}

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);
}
}
Usage:
HintTextField field = new HintTextField();
field.setHint("Here's a hint");

Answer 2

JOptionPane.showConfirmDialog (null, "本文档正在打印。允许要打印吗？", "友情提示", JOptionPane.YES_NO_OPTION);