java 更改另一个类中静态变量的值
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Changing the value of static variables in another class
提问by Charlie Landrigan
I am trying to display a character moving across the screen but the x and y variables stay the same. I am under the impression that when I change the value of a static variable it changes in every instance of the class.
我试图显示一个在屏幕上移动的字符，但 x 和 y 变量保持不变。我的印象是，当我更改静态变量的值时，它会在类的每个实例中更改。
here is the class where is meant to move the character
这是用于移动角色的课程
public class MoveChara {
private static int x, y;
private int dx, dy;
public void init() {
x = 30;
y = 50;
dx = 1;
dy = 1;
}
public void move() {
x += dx;
y += dy;
}
public int getX() {
return x;
}
public int getY() {
return y;
}
}
here is part of the class that calls the move method
这是调用 move 方法的类的一部分
public class Game implements Runnable {
private MoveChara move;
private boolean running = false;
public void run() {
init();
while(running) {
tick();
render();
}
stop();
}
private void init() {
move = new MoveChara;
}
private void tick() {
move.move();
}
}
and in the method that draws the character
并在绘制字符的方法中
public class Draw extends JPanel {
public MoveChara move;
public ImageMake imgm;
@Override
public void paintComponent(Graphics g) {
imgm = new ImageMake();
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g;
move = new MoveChara();
move.init();
g2d.drawImage(
imgm.createImg("Images/SpriteSheet.png"),
move.getX(),
move.getY(),
this
);
}
}
回答by goncalopinto
A static variable belongs to the class not to an instance of the class. To access a static variable from outside of its class you can do it like this:
静态变量属于类而不属于类的实例。要从其类外部访问静态变量，您可以这样做：
claasName.variablename = newValue;
Inside the paintComponentmethod there is a call to the init method in the parent class, this is initializing x and y everytime it is called. If you move the initialization to the static variables declarations this dhould work.
Let me know if it's this you are looking for.
在该paintComponent方法内部调用了父类中的 init 方法，每次调用时都会初始化 x 和 y。如果您将初始化移动到静态变量声明，这应该可行。如果这就是您要找的，请告诉我。
回答by Top Sekret
Static variables are shared across instances of the class. When edited, they change for all instances.
静态变量在类的实例之间共享。编辑后，它们会更改所有实例。
