我需要在if语句之外使用变量.它说如果最后我需要做,但如果我尝试使用它将无法工作

Question

我有这个代码:

public void onPlayerInteract(PlayerInteractEvent event) {
    final Action action = event.getAction();
    Location l1 = null;
    Location l2 = null;
    if (action == Action.LEFT_CLICK_BLOCK){
        l1 = event.getClickedBlock().getLocation();
    } else if (action == Action.RIGHT_CLICK_BLOCK) {
        l2 = event.getClickedBlock().getLocation();
    }

    Thread t = new Thread() {
        @Override
        public void run() {
            while(true) {
                try {
                    Thread.sleep(1000*60*60);
                    Location maxx = l1.getX();
                    Location maxy = l1.getY();
                    Location maxz = l1.getZ();

                    Location minx = l2.getX();
                    Location miny = l2.getY();
                    Location minz = l2.getZ();

                    if(l1.getX() > l2.getX()){
                        //I can't execute this, errors!
                    }
                } catch (InterruptedException ie) {
                }
            }
        }
    };
    t.start();

它给了我错误,并说要将l1和l2改为决赛.如果我将l1和l2更改为决赛,它会给我另一个错误,即l1 =等等,它表示要删除最后一个.

Answer 1

l1并且l2是方法的局部变量onPlayerInteract().在此方法中,您将创建一个使用这些局部变量l1和的匿名内部类l2.这是如果只可能l1和l2是最终的决定.但是根据定义,最终变量只能分配一次,然后分配null,然后为它们分配另一个值.因此,您需要复制l1和复制l2最终变量,并在匿名类中使用这些最终副本:

public void onPlayerInteract(PlayerInteractEvent event) {
    final Action action = event.getAction();
    Location l1 = null;
    Location l2 = null;
    if (action == Action.LEFT_CLICK_BLOCK){
        l1 = event.getClickedBlock().getLocation();
    } else if (action == Action.RIGHT_CLICK_BLOCK) {
        l2 = event.getClickedBlock().getLocation();
    }

    final Location l1Final = l1;
    final Location l2Final = l2;

    Thread t = new Thread() {
        @Override
        public void run() {
            while(true) {
                try {
                    Thread.sleep(1000*60*60);
                    Location maxx = l1Final.getX();
                    Location maxy = l1Final.getY();
                    Location maxz = l1Final.getZ();

                    Location minx = l2Final.getX();
                    Location miny = l2Final.getY();
                    Location minz = l2Final.getZ();


                    if(l1Final.getX() > l2Final.getX()){
                        // ...
                    }
                } catch (InterruptedException ie) {
                }
            }
        }
    };
    ...
}