如何等待 Android 對話框完成？

Question

我正在做一個逃脫游戲，我有一個 useObjectButton。 單擊時，它會顯示一個帶有 ListView 的對話框，我希望它在玩家單擊對話框的某個項目后更新信息。 但是，它會立即更新，我不知道如何修復它。

我的對話框如下所示：

public Inventory.ITEM selectItem() {

        if (game.inventory.isEmpty()) {

            Toast.makeText(this, "Inventory is empty", Toast.LENGTH_SHORT).show();
            return null;

        } else {

            AlertDialog inventoryDialog;
            AlertDialog.Builder inventoryDialogBuilder = new AlertDialog.Builder(ActivityGame.this);
            View inventoryPopup = getLayoutInflater().inflate(R.layout.inventory, null, false);

            inventoryDialogBuilder.setView(inventoryPopup);
            inventoryDialog = inventoryDialogBuilder.create();
            inventoryDialog.setCancelable(true);

            ListView lvInventory = inventoryPopup.findViewById(R.id.inventory_lv);

            if (!game.inventory.isEmpty()) {

                ArrayAdapter adapter = new ArrayAdapter(ActivityGame.this, android.R.layout.simple_list_item_1, game.inventory.getInventory());
                lvInventory.setAdapter(adapter);
                   
                lvInventory.setOnItemClickListener((parent, view, position, id) -> {
                    selectedItem = game.inventory.getItem(position);
                    inventoryDialog.dismiss();    
                });    

                inventoryDialog.show();

            }
        }
}

我在各種函數中調用它，例如：

btnUseObject.setOnClickListener(v -> {
            Inventory.ITEM item=selectItem();
            info.setText(game.nightStand.useObject(item));
            if(game.nightStand.isUnlocked()) {
                btnDrawer1.setEnabled(true);
                btnDrawer2.setEnabled(true);
            }
        });

Answer 1

首先，您必須了解這些指令的異步性質：

Inventory.ITEM item=selectItem();

和

lvInventory.setOnItemClickListener((parent, view, position, id) -> {
    selectedItem = game.inventory.getItem(position);
    inventoryDialog.dismiss();    
});

您不能讓此方法返回 selectedItem 的值，因為它在執行時是未知的。 將單擊偵聽器綁定到按鈕的時間與用戶實際單擊按鈕的操作不同。 你應該做的是給一個 function 作為異步 function 的參數，當用戶單擊按鈕時，它會被調用。 像這樣的東西：

    public void selectItem(Consumer callbackFn) {
        if (game.inventory.isEmpty()) {
            Toast.makeText(this, "Inventory is empty", Toast.LENGTH_SHORT).show();
            return;
        }
        
        AlertDialog inventoryDialog;
        AlertDialog.Builder inventoryDialogBuilder = new AlertDialog.Builder(ActivityGame.this);
        View inventoryPopup = getLayoutInflater().inflate(R.layout.inventory, null, false);
    
        inventoryDialogBuilder.setView(inventoryPopup);
        inventoryDialog = inventoryDialogBuilder.create();
        inventoryDialog.setCancelable(true);
    
        ListView lvInventory = inventoryPopup.findViewById(R.id.inventory_lv);
        ArrayAdapter adapter = new ArrayAdapter(ActivityGame.this, android.R.layout.simple_list_item_1, game.inventory.getInventory());
        lvInventory.setAdapter(adapter);
            
        lvInventory.setOnItemClickListener((parent, view, position, id) -> {
            // The asynchronous function that gets called whenever an user clicks a button. 
            // You cannot return a value from it because it is not immediately known at execution time.
            callbackFn.accept(game.inventory.getItem(position));
            inventoryDialog.dismiss();    
        });
    
    inventoryDialog.show();
}

接着

btnUseObject.setOnClickListener(v -> {
    Consumer callbackFn = (Inventory.ITEM item) -> {
        info.setText(game.nightStand.useObject(item));
        if (game.nightStand.isUnlocked()) {
            btnDrawer1.setEnabled(true);
            btnDrawer2.setEnabled(true);
        }
    };

    selectItem(callbackFn); // When an user clicks the button, please execute my callback function
});