Android 当我单击打开弹出窗口的按钮时，应用程序崩溃

我正在尝试一个弹出窗口，它有一个EditText字段供用户输入新预算，还有一个保存值的按钮。单击“保存”按钮后，主活动中的文本视图应根据用户在弹出窗口的预算（EditText）中输入的内容进行更改。但是，当我为popupwindow中的“保存”按钮实现OnClickListener时，一旦我尝试从主活动导航到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);
            }
        });


    }

上面的代码显示了从主活动打开PopupWindow的OnClick方法。“button_savebudget”用于保存值并更改主活动中的文本视图

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);
            }
        });


    }

日志如下：-

    --------- 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\u savebudget”是导致崩溃的原因，因为一旦我删除了那段特定的代码，应用程序就不会崩溃，但我不确定还需要修改什么来修复它

试试看

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

---

为什么不使用自定义对话框？请尝试此按钮\u savebudget=popupView。findViewById（R.id.budget\u save）；这管用！谢谢！！