英文:
Final variable being changed without any = statements
问题
int[] mouseCoordinates = new int[2]; // 获取点击的坐标
mouseCoordinates = mouseListenerExample.getCoordinates();
final int[] baseCoordinates = mouseCoordinates; // 基准坐标（无点击）问题所在//
int[][] totalCoordinates = new int[4][2]; // 收集4次鼠标点击的所有坐标
for (int i = 0; i < 4; i++){ // 目标是获取4次点击的坐标
while (mouseCoordinates[0] == baseCoordinates[0]){
mouseCoordinates = mouseListenerExample.getCoordinates(); // 问题出在这里：当 mouseListenerExample.getCoordinates() 发生变化时，mouseCoordinates 也会改变，baseCoordinates 也在改变，尽管不应该有这种情况发生。
if (mouseCoordinates[0] != baseCoordinates[0]) {
break;
}
}
totalCoordinates[i] = mouseListenerExample.getCoordinates();
mouseListenerExample.setCoordinates(baseCoordinates);
mouseCoordinates = baseCoordinates;
}
英文:
I'm making an autoclicking project in java for personal use, and using the following method to get coordinates of a click from a class that extends MouseAdapter. The click is being done on a JFrame.
int[] mouseCoordinates = new int[2]; //The coordinates of the click
mouseCoordinates = mouseListenerExample.getCoordinates();
final int[] baseCoordinates = mouseCoordinates; //The base coordinates (no click) which is this problem//
int[][] totalCoordinates = new int[4][2]; //An array that collects all coordinates of 4 mouse clicks
for (int i = 0; i < 4; i++){ //the goal is to get the coordinates of 4 clicks
while (mouseCoordinates[0] == baseCoordinates[0]){
mouseCoordinates = mouseListenerExample.getCoordinates(); //The problem occurs here: when mouseListenerExample.getCoordinates() changes, mouseCoordinates is changed, baseCoordinates is also changing, which it shouldnt, since there are no statements that say so.
if (mouseCoordinates[0] != baseCoordinates[0]) {
break;
}
}
totalCoordinates[i] = mouseListenerExample.getCoordinates();
mouseListenerExample.setCoordinates(baseCoordinates);
mouseCoordinates = baseCoordinates;
}
Is there some statement that is changing baseCoordinates that I am missing?
答案1
得分: 1
你的 baseCoordinates 变量已被声明为 final，因此它是不可变的，但由于它是一个 int[] 或整型数组，它是一个引用变量，所以不能改变的是引用本身，而不是引用的状态，因此数组内部的整数是可以（在你的情况下确实）改变的。
你正在改变 mouseCoordinates 保存的值。由于 baseCoordinates 引用的是完全相同的 int[] 对象，这也会相应地改变 baseCoordinates 的值。如果你不希望它被改变，最好为最终变量创建一个全新的整型数组对象。
可以这样做：
final int[] baseCoordinates = new int[mouseCoordinates.length];
System.arraycopy(mouseCoordinates, 0, baseCoordinates, 0, mouseCoordinates.length);
英文:
Your baseCoordinates variable has been declared final, and so it cannot change, but since it is an int[] or int-array, it is a reference variable, and so what cannot change is the reference itself, not the state of the reference, and so the ints held within the array can (and in your case -- do) change.
You're changing the values held by mouseCoordinates. Since the baseCoordinates refers to the exact same int[] object, then this will likewise change the values for baseCoordinates. Best to create a completely new int object for the final variable if you don't want it changed.
Do something like:
final int[] baseCoordinates = new int[mouseCoordinates.length];
System.arraycopy( mouseCoordinates, 0, baseCoordinates , 0, mouseCoordinates.length );
答案2
得分: 0
所以在大致查看了一下后，我只是将数组替换为单独的整数，并在跳出循环之前添加了一个打印语句，这样就使得它正常工作了。
英文:
So after some looking around, i just replaced the arrays with individual ints, and added a print statement right before the break, and it made it work.
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