Given the following program class Game { private static final int DELAY = 500; private int x; public Game() { x = 0; } public void addX() { try { int y = x; Thread.sleep((int) (DELAY * Math.random())); y += 1; x = y; System.out.println("x=" + x); } catch (InterruptedException e) { } } } public class Homework8 { public static void main(String[] args) { var game = new Game(); for (int i = 0; i < 2; i++) { new Thread(() -> { for (int j = 0; j < 2; j++) game.addX(); }).start(); } } } The output could be x=1 x=1 x=2 x=2 or x=1 x=2 x=1 x=2 However, we desire the output to be x=1 x=2 x=3 x=4 1. Modify the addX method using "synchronized" to get the desired output.
时间: 2023-12-15 08:05:05 浏览: 87
To get the desired output of x=1 x=2 x=3 x=4, we need to ensure that the threads execute the addX() method in a synchronized manner. Here's the modified Game class with synchronized:
```
class Game {
private static final int DELAY = 500;
private int x;
public Game() {
x = 0;
}
public synchronized void addX() {
try {
int y = x;
Thread.sleep((int) (DELAY * Math.random()));
y += 1;
x = y;
System.out.println("x=" + x);
} catch (InterruptedException e) {
}
}
}
```
In the modified addX() method, we have added the synchronized keyword to ensure that only one thread can execute it at a time. This will prevent two threads from accessing and modifying the x variable at the same time, which was causing the wrong output.
Now, when we run the Homework8 class, the output will always be x=1 x=2 x=3 x=4.
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