Java 键侦听器事件未触发?
我希望能够注册一个触发布尔变量的按键事件。我在我的主课上做过,但现在我试着把它放到课堂上,它似乎不起作用 这是英雄班:Java 键侦听器事件未触发?,java,applet,Java,Applet,我希望能够注册一个触发布尔变量的按键事件。我在我的主课上做过,但现在我试着把它放到课堂上,它似乎不起作用 这是英雄班: public class Hero extends Main { private boolean downPressed; private boolean leftPressed; private boolean rightPressed; public void init() { } public void paint(Graphics g, int x_pos, int
public class Hero extends Main {
private boolean downPressed;
private boolean leftPressed;
private boolean rightPressed;
public void init() {
}
public void paint(Graphics g, int x_pos, int y_pos) {
if (isDownPressed() && isLeftPressed()) {
this.sprite = hero225;
} else if (isDownPressed() && isRightPressed()) {
this.sprite = hero135;
} else if (isUpPressed() && isRightPressed()) {
this.sprite = hero45;
} else if (isUpPressed() && isLeftPressed()) {
this.sprite = hero315;
} else if (isLeftPressed() == true) {
this.sprite = hero270;
} else if (isRightPressed() == true) {
this.sprite = hero90;
} else if (isUpPressed() == true) {
this.sprite = hero;
System.out.println("Succsess");
} else if (isDownPressed() == true) {
this.sprite = hero180;
}
// this.sprite will contain value set on last "movement"
g.drawImage(this.sprite, x_pos, y_pos, this);
}
public void keyPressed(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
setLeftPressed(true);
System.out.println("keyPressed");
}
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
setRightPressed(true);
}
if (e.getKeyCode() == KeyEvent.VK_UP) {
setUpPressed(true);
}
if (e.getKeyCode() == KeyEvent.VK_DOWN) {
setDownPressed(true);
}
}
public void keyReleased(KeyEvent e) {
if (e.getKeyCode() == KeyEvent.VK_LEFT) {
setLeftPressed(false);
}
if (e.getKeyCode() == KeyEvent.VK_RIGHT) {
setRightPressed(false);
}
if (e.getKeyCode() == KeyEvent.VK_UP) {
setUpPressed(false);
}
if (e.getKeyCode() == KeyEvent.VK_DOWN) {
setDownPressed(false);
}
}
public void keyTyped(KeyEvent e) {
}
public void mouseClicked(MouseEvent e) {
System.out.println("HIT!");
}
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
public void mousePressed(MouseEvent e) {
boolean isButtonPressed = true;
}
public void mouseReleased(MouseEvent e) {
boolean isButtonPressed = false;
}
public void setDownPressed(boolean downPressed) {
this.downPressed = downPressed;
}
public boolean isDownPressed() {
return downPressed;
}
public void setLeftPressed(boolean leftPressed) {
this.leftPressed = leftPressed;
}
public boolean isLeftPressed() {
return leftPressed;
}
public void setRightPressed(boolean rightPressed) {
this.rightPressed = rightPressed;
}
public boolean isRightPressed() {
return rightPressed;
}
public void setUpPressed(boolean upPressed) {
this.upPressed = upPressed;
}
public boolean isUpPressed() {
return upPressed;
}
下面是调用它的level类:
public class Level extends Main {
Hero hero = new Hero();
public void paint(KeyEvent e, Graphics g, double x_pos, double x_pos2) {
repaint();
}
这是主类中的Paint函数,它调用:
public void paint(Graphics g) {
Level level = new Level();
level.paint(e, g, x_pos, y_pos);
造成这种情况的问题似乎并不明显。您应该在要侦听事件的类中实现
java.awt.event.keystener
接口,在本例中,是Hero,因此:
public class Hero extends Main implements java.awt.event.KeyListener
然后使用某种方法(可能是init或其他方法)注册事件,使用:
addKeyListener(this);
//rest of your code
或者,如果您只想侦听某些事件,可以注册适配器,而不是实现接口KeyListener:
addKeyListener(new java.awt.KeyAdapter()
{
public void keyPressed(java.awt.KeyEvent e)
{
//handle just this event
}
}
);
//rest of of your code
您应该在要侦听事件的类中实现
java.awt.event.KeyListener
接口,在本例中为Hero,因此:
public class Hero extends Main implements java.awt.event.KeyListener
然后使用某种方法(可能是init或其他方法)注册事件,使用:
addKeyListener(this);
//rest of your code
或者,如果您只想侦听某些事件,可以注册适配器,而不是实现接口KeyListener:
addKeyListener(new java.awt.KeyAdapter()
{
public void keyPressed(java.awt.KeyEvent e)
{
//handle just this event
}
}
);
//rest of of your code
听起来像是焦点问题:只有活动组件才会获得KeyEvents
有几种方法可以解决这个问题,但我发现教程很好地涵盖了这些想法。但是如果你想要一个快速而肮脏(肮脏?不确定,简单和简单对我来说还不错;对于大型项目来说只是有点臃肿)的解决方案,你可以为每个组件实现一个监听器,并将事件转发给某个处理它的通用类。听起来像是一个焦点问题:只有活动组件才会获得KeyEvents
有几种方法可以解决这个问题,但我发现教程很好地涵盖了这些想法。但是,如果您想要一个快速而肮脏(肮脏?不确定,简单和简单对我来说还不错;对于大型项目来说只是有点臃肿)的解决方案,您可以为每个组件实现一个侦听器,并将事件转发给处理它的某个通用类。当我执行第二步时,我会遇到这个错误:方法addEventListener(Hero)是未定义的类型,英雄设法让它在英雄类中工作(呜呜!),但它在等级类中不工作。我所做的是放置一个System.out.println(“按键”);在if(isDownPressed()&&isLeftPressed())中{。但是当我加载级别并按left时,控制台中什么也没有发生:(为什么要在不同的类中出于相同的目的侦听相同的事件,您应该检查您的设计我在执行第二步时遇到此错误:方法addEventListener(Hero)类型未定义,Hero设法使其在Hero类中工作(Woop!),但在Level类中不工作。我所做的是在if(isDownPressed()&&isLeftPressed())中放置System.out.println(“keyPressed”){。但是当我加载Level并按下left时,控制台中没有发生任何事情:(为什么要在不同的课程中出于相同的目的收听相同的事件?您应该查看您的设计+1“要触发键盘事件,组件必须具有键盘焦点。”—+1”要触发键盘事件,组件必须具有键盘焦点。”-