我正在使用NetBeans作为IDE使用Swing用Java构建Snake and Ladders游戏。问题是,当我编写一个函数处理另一个类中的主类的GUI的某些方面(例如,设置标签的图标)时,应用程序运行,但使用该函数中的代码必须进行的更改却没有”申请。
import javax.swing.JLabel;
import javax.swing.JOptionPane;
public class Game extends javax.swing.JFrame
{
protected javax.swing.JLabel diceLabel;
private static final Dice diceObj = new Dice();
protected int diceNumber;
private void dicePlayer1ButtonActionPerformed(java.awt.event.ActionEvent evt) {
diceObj.setDiceIMG(diceNumber);
}
public static void main(String args[]){
java.awt.EventQueue.invokeLater(new Runnable()
{
public void run()
{
new Game().setVisible(true);
}
});
}
}
class Dice extends Game
{
public void setDiceIMG(int dice)
{
if(dice == 1)
{
diceLabel.setIcon(new javax.swing.ImageIcon("D:\\dice\\dice11.jpg"));
}
else if(dice == 2)
{
diceLabel.setIcon(new javax.swing.ImageIcon("D:\\dice\\dice22.jpg"));
}
else
{
diceLabel.setIcon(new javax.swing.ImageIcon("D:\\dice\\dice66.jpg"));
}
}
}
如果我运行此代码,则不会在标签上设置图像,但是如果我在Game类中设置setDiceIMG函数,则它可以完美运行。有关此的任何信息都将有所帮助。
MadProgrammer评论的基本解决方案或“新手方法”是将diceLabel
的引用路径传递给Dice
构造函数或setDiceIMG
方法,如以下mre所示:
import java.awt.BorderLayout;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Random;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingConstants;
public class Game extends JFrame
{
protected JLabel diceLabel;
private final Dice diceObj; //should not be static
protected int diceNumber;
Game() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
diceLabel = new JLabel();
diceLabel.setHorizontalAlignment(SwingConstants.CENTER);
JButton changeIcon = new JButton("Change Icon");
changeIcon.addActionListener(e -> changeLabelIcon());
diceObj = new Dice(diceLabel); //path a reference of the lable to Dice
changeLabelIcon();
add(diceLabel, BorderLayout.NORTH);
add(changeIcon, BorderLayout.SOUTH);
pack();
}
private void changeLabelIcon() {
diceNumber = new Random().nextInt(3);
diceObj.setDiceIMG(diceNumber);
}
public static void main(String args[]){
java.awt.EventQueue.invokeLater(() -> new Game().setVisible(true));
}
}
class Dice // no need to extend Game
{
//use web resources to make code mre
private static final String[] CIRCLES_64 = {
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Green.png",
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Red.png",
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Yellow.png",
};
private final JLabel diceLabel;
Dice(JLabel diceLabel) {
this.diceLabel = diceLabel;
}
public void setDiceIMG(int dice)
{
try {
if(dice == 1)
{
diceLabel.setIcon(new ImageIcon(new URL(CIRCLES_64[0])));
}
else if(dice == 2)
{
diceLabel.setIcon(new ImageIcon(new URL(CIRCLES_64[1])));
}
else
{
diceLabel.setIcon(new ImageIcon(new URL(CIRCLES_64[2])));
}
} catch (MalformedURLException ex) {
ex.printStackTrace();
}
}
}
[通过引入视图和Dice
之间共享的模型可以实现更好的设计:
public class Game extends JFrame
{
protected JLabel diceLabel;
private final Dice diceObj; //should not be static
private final DiceModel model;
Game() {
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setLocationRelativeTo(null);
diceLabel = new JLabel();
diceLabel.setHorizontalAlignment(SwingConstants.CENTER);
JButton changeIcon = new JButton("Change Icon");
changeIcon.addActionListener(e -> changeLabelIcon());
model = new DiceModel(4);
diceObj = new Dice(model);
changeLabelIcon();
add(diceLabel, BorderLayout.NORTH);
add(changeIcon, BorderLayout.SOUTH);
pack();
}
private void changeLabelIcon() {
model.rollDice();
diceLabel.setIcon(new ImageIcon(diceObj.imageURL()));
}
public static void main(String args[]){
java.awt.EventQueue.invokeLater(() -> new Game().setVisible(true));
}
}
class DiceModel {
private int diceNumber;
private final int max;
private final Random rnd;
DiceModel(int max) {
this.max = max;
rnd = new Random();
diceNumber = 0;
}
void rollDice() {
diceNumber = rnd.nextInt(max+1);
}
int getDiceNumber(){
return diceNumber;
}
}
class Dice
{
//use web resources to make code mre
private static final String[] CIRCLES_64 = {
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Green.png",
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Red.png",
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Yellow.png",
};
private final DiceModel model;
Dice(DiceModel model) {
this.model = model;
}
URL imageURL()
{
try {
if(model.getDiceNumber() <= CIRCLES_64.length && model.getDiceNumber() > 0)
return new URL(CIRCLES_64[model.getDiceNumber()-1]);
else
return new URL(CIRCLES_64[0]);
} catch (MalformedURLException ex) {
ex.printStackTrace();
}
return null;
}
}
下一个改进可能是重构代码以添加一个控制器来遵循MVC设计模式:
import java.awt.BorderLayout;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Random;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.SwingConstants;
import javax.swing.event.ChangeListener;
public class Game //acts as game controller
{
Game() {
DiceModel model = new DiceModel();
View view = new View(model);
view.update();//initialize icon
model.setListener(e->view.update());//respond to model changes
view.setVisible(true);
}
public static void main(String args[]){
java.awt.EventQueue.invokeLater(() -> new Game());
}
}
class View{
private final JLabel diceLabel;
private final DiceModel model;
private final JFrame frame;
View(DiceModel model) {
this.model = model;
frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
diceLabel = new JLabel();
diceLabel.setHorizontalAlignment(SwingConstants.CENTER);
JButton changeIcon = new JButton("Roll Dice");
changeIcon.addActionListener(e -> model.rollDice()); //change model
frame.add(diceLabel, BorderLayout.NORTH);
frame.add(changeIcon, BorderLayout.SOUTH);
}
void setVisible(boolean visible){
frame.pack();
frame.setVisible(visible);
}
void update() {
diceLabel.setIcon(new ImageIcon(model.imageURL()));
}
}
class DiceModel {
//use web resources to make code mre
private static final String[] CIRCLES_64 = {
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Green.png",
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Red.png",
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Yellow.png",
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Blue.png",
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Orange.png",
"https://cdn3.iconfinder.com/data/icons/softwaredemo/PNG/64x64/Circle_Grey.png"
};
private int diceNumber;
private final Random rnd;
private ChangeListener listener;
DiceModel() {
rnd = new Random();
diceNumber = 0;
}
void rollDice() {
diceNumber = rnd.nextInt(CIRCLES_64.length);
notifyListener();
}
int getDiceNumber(){
return diceNumber;
}
void notifyListener(){
if(listener != null){
listener.stateChanged(null);
}
}
void setListener(ChangeListener listener) {
this.listener = listener;
}
URL imageURL()
{
try {
return new URL(CIRCLES_64[diceNumber]);
} catch (MalformedURLException ex) {
ex.printStackTrace();
}
return null;
}
}
运行on line。
绝对可以使用(创建,引用)来自多个类的Swing组件。通常,除了“ Hello world”之外,仅包含一个类是非常不寻常的。
正确的方法是创建自己的专用组件(可能从JPanel派生),以创建和管理它们拥有的所有组件(例如,具有所有按钮和文本的对话框)。将它们专用于呈现数据也非常好,而任何逻辑,计算和IO都应在单独的类中完成。了解有关model-view-controller的信息。一些复杂的Swing类(如JTable)已经通过这种方式实现。