android - 当我单击打开弹出窗口的按钮时，应用程序崩溃

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2年前关闭。




我正在尝试使用一个具有EditText字段的弹出窗口，供用户输入新预算和一个用于保存值的按钮。单击“保存”按钮后，主 Activity 中的TextView应该根据用户在弹出窗口中输入的预算(EditText)中的内容而变化。但是，当我为popupwindow中的“保存”按钮实现OnClickListener时，一旦我尝试从主 Activity 导航到popupwindow，应用程序就会崩溃。

public void onButtonShowPopupWindowClick(View view) {

        // inflate the layout of the popup window
        LayoutInflater inflater = (LayoutInflater)
                getSystemService(LAYOUT_INFLATER_SERVICE);
        View popupView = inflater.inflate(R.layout.spending_budgetpopup, null);

        // create the popup window
        int width = RelativeLayout.LayoutParams.WRAP_CONTENT;
        int height = RelativeLayout.LayoutParams.WRAP_CONTENT;
        boolean focusable = true; // lets taps outside the popup also dismiss it
        final PopupWindow popupWindow = new PopupWindow(popupView, width, height, focusable);

        // show the popup window
        // which view you pass in doesn't matter, it is only used for the window tolken
        popupWindow.showAtLocation(view, Gravity.CENTER, 0, 0);

        // dismiss the popup window when touched
        popupView.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View v, MotionEvent event) {
                popupWindow.dismiss();
                return true;
            }
        });



        Button button_savebudget = findViewById(R.id.budget_save);


        button_savebudget.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                String budget = newbudget.getText().toString();
                amount_budget.setText(budget);
            }
        });


    }

上面的代码显示了OnClick方法，该方法从主要 Activity 中打开PopupWindow。而“button_savebudget”是保存值并在主 Activity 中更改TextView。

的logcat如下:

    --------- beginning of crash
10-11 16:08:25.552 4980-4980/com.example.hannzern1998.spendingtest E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.hannzern1998.spendingtest, PID: 4980
    java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
        at com.example.hannzern1998.spendingtest.MainActivity.onButtonShowPopupWindowClick(MainActivity.java:100)
        at com.example.hannzern1998.spendingtest.MainActivity$1.onClick(MainActivity.java:44)
        at android.view.View.performClick(View.java:6294)
        at android.view.View$PerformClick.run(View.java:24770)
        at android.os.Handler.handleCallback(Handler.java:790)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:164)
        at android.app.ActivityThread.main(ActivityThread.java:6494)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)

我很确定“button_savebudget”是导致崩溃的原因，因为一旦删除了特定的代码段，应用程序就不会崩溃，但是我不确定还有什么要修改的!

最佳答案

尝试

Button button_savebudget = popupView.findViewById(R.id.budget_save);

关于android - 当我单击打开弹出窗口的按钮时，应用程序崩溃，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/52755236/

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Answer 1

尝试

Button button_savebudget = popupView.findViewById(R.id.budget_save);