Question

我正在尝试使用PopupWindow来解释我的应用，但是对于看似简单的事情，我遇到了很多困难。我尝试了各种各样的YouTube视频，看了几乎所有关于它的类似帖子，但我还没有运气。如果有人可以指出我的缺点，那就太棒了。

我的最终目标是PopupWindow与on create方法一起出现，但我现在包含一个Button来启动它，因为所有教程都包含一个。

 protected void onCreate(Bundle savedInstanceState) {
    //BUILDING THE POP UP WINDOW ON CLICK OF HELP BUTTON

    help=(Button)findViewById(R.id.help);
    help.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            layoutInflater=(LayoutInflater)getBaseContext().getSystemService(LAYOUT_INFLATER_SERVICE);
            View customView= layoutInflater.inflate(R.layout.activity_instructions, null);

            popUpWindow=new PopupWindow(
                    customView,
                    RelativeLayout.LayoutParams.WRAP_CONTENT,
                    RelativeLayout.LayoutParams.WRAP_CONTENT
            );
            myButton.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View view) {
                    popUpWindow.dismiss();
                }
            });
        }
    });

非常感谢任何帮助。如果我需要提供更多信息，请询问。我是android新手，这是我的第一个大应用程序，所以保持我的希望。

由于 The link to my log

07-30 23:32:07.062 9273-9273/my.myCompany.vinay.diversityformulaapplication E/AndroidRuntime: FATAL EXCEPTION: main
                                                                                              Process: my.myCompany.vinay.diversityformulaapplication, PID: 9273
                                                                                              java.lang.RuntimeException: Unable to start activity ComponentInfo{my.myCompany.vinay.diversityformulaapplication/my.myCompany.vinay.diversityformulaapplication.EntryScreen}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
                                                                                                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2947)
                                                                                                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3008)
                                                                                                  at android.app.ActivityThread.-wrap14(ActivityThread.java)
                                                                                                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1650)
                                                                                                  at android.os.Handler.dispatchMessage(Handler.java:102)
                                                                                                  at android.os.Looper.loop(Looper.java:154)
                                                                                                  at android.app.ActivityThread.main(ActivityThread.java:6688)
                                                                                                  at java.lang.reflect.Method.invoke(Native Method)
                                                                                                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1468)
                                                                                                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1358)
                                                                                               Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.Button.setOnClickListener(android.view.View$OnClickListener)' on a null object reference
                                                                                                  at my.myCompany.vinay.diversityformulaapplication.EntryScreen.onCreate(EntryScreen.java:37)
                                                                                                  at android.app.Activity.performCreate(Activity.java:6912)
                                                                                                  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1126)
                                                                                                  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2900)
                                                                                                  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3008) 
                                                                                                  at android.app.ActivityThread.-wrap14(ActivityThread.java) 
                                                                                                  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1650) 
                                                                                                  at android.os.Handler.dispatchMessage(Handler.java:102) 
                                                                                                  at android.os.Looper.loop(Looper.java:154) 
                                                                                                  at android.app.ActivityThread.main(ActivityThread.java:6688) 
                                                                                                  at java.lang.reflect.Method.invoke(Native Method) 
                                                                                                  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1468) 
                                                                                                  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1358)

Answer 1

myButton 在此处为空。
您错过了这个

myButton = (Button)customView.findViewById(R.id.myButtonId);

弹出窗口 - 继续崩溃

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