Hey all I am having an issue fixing the following error:

java.lang.RuntimeException: Unable to start activity ComponentInfo{com.xxxxxxxxxxxx/com.xxxxxxxxxxx.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.reflect.Method.getName()' on a null object reference
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3270)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409)
    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83)
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135)
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95)
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016)
    at android.os.Handler.dispatchMessage(Handler.java:107)
    at android.os.Looper.loop(Looper.java:214)
    at android.app.ActivityThread.main(ActivityThread.java:7356)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)
 Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.String java.lang.reflect.Method.getName()' on a null object reference
    at com.xxxxxxxxxxxx.model.GlobalCls.logData(GlobalCls.java:301)
    at com.xxxxxxxxxxxx.MainActivity.onCreate(MainActivity.java:248)
    at android.app.Activity.performCreate(Activity.java:7802)
    at android.app.Activity.performCreate(Activity.java:7791)
    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1299)
    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3245)
    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3409) 
    at android.app.servertransaction.LaunchActivityItem.execute(LaunchActivityItem.java:83) 
    at android.app.servertransaction.TransactionExecutor.executeCallbacks(TransactionExecutor.java:135) 
    at android.app.servertransaction.TransactionExecutor.execute(TransactionExecutor.java:95) 
    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:2016) 
    at android.os.Handler.dispatchMessage(Handler.java:107) 
    at android.os.Looper.loop(Looper.java:214) 
    at android.app.ActivityThread.main(ActivityThread.java:7356) 
    at java.lang.reflect.Method.invoke(Native Method) 
    at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930) 

My code I'm calling:

@Override
protected void onCreate(Bundle savedInstanceState) {
    this.getWindow().setType(WindowManager.LayoutParams.TYPE_KEYGUARD_DIALOG);
    GlobalCls.hideSystemUI(getWindow());
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    
    ... more code here...
    if (GlobalCls.isDebugging) { GlobalCls.logData(true, new Object(){}.getClass(), null); }
    ... more code here...
}

And the class I am calling GlobalCls:

 public static void logData(Boolean isErr, Class _c, List<String> txt, String... _Other) {
    String methodName = _c.getClass().getEnclosingMethod().getName();
    String className = _c.getClass().getEnclosingClass().getSimpleName();
    Log.d("app", className   ":"   methodName);
    ... more code here...
 }

The error being on this line of code:

 _c.getClass().getEnclosingMethod().getName();

I am not understanding why I am getting that error when I know _c has data and is not null?

If I call the same code but within the same class function it works as it should:

So, what am I missing here?

CodePudding user response：

The error says it all, by passing in new Object(){}.getClass():

if (GlobalCls.isDebugging) { GlobalCls.logData(true, new Object(){}.getClass(), null); }

you have passed a null/empty Object which you translated into a null Class into your method, hence it throws a NullPointerException (which is literally on top of your huge error message).

Try passing in something else that is not a new Object() and it should work.

Also, this question is similar to object is null even after instantiating it

CodePudding user response：

Simple error (probably from refactoring?), you are doing _c.getClass() thus getting a Class object for java.lang.Class which in turn is not a local or anonymous class and consequently getEnclosingMethod() returns null on which you then try to invoke getName().

remove the extra call:

public static void logData(Boolean isErr, Class _c, List<String> txt, String... _Other) {
    String methodName = _c.getEnclosingMethod().getName();
    String className = _c.getEnclosingClass().getSimpleName();
    ... more code here...
}