E/AndroidRuntime: FATAL EXCEPTION: main [dupli]

Question

When I run my application something went wrong and I got this error:

05-09 09:23:21.215 9003-9003/? I/art: Late-enabling -Xcheck:jni 05-09 09:23:21.544 9003-9003/com.example.aryan.lb_minisquad_re2 D/AndroidRuntime: Shutting down VM 05-09 09:23:21.545 9003-9003/com.example.aryan.lb_minisquad_re2 E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.aryan.lb_minisquad_re2, PID: 9003 java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.aryan.lb_minisquad_re2/com.example.aryan.lb_minisquad_re2.MainActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.Window.findViewById(int)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2236) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) at android.app.ActivityThread.access$800(ActivityThread.java:151) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5254) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'android.view.View android.view.Window.findViewById(int)' on a null object reference at android.app.Activity.findViewById(Activity.java:2072) at com.example.aryan.lb_minisquad_re2.MainActivity.(MainActivity.java:19) at java.lang.reflect.Constructor.newInstance(Native Method) at java.lang.Class.newInstance(Class.java:1606) at android.app.Instrumentation.newActivity(Instrumentation.java:1066) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2226) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2387) at android.app.ActivityThread.access$800(ActivityThread.java:151) at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1303) at android.os.Handler.dispatchMessage(Handler.java:102) at android.os.Looper.loop(Looper.java:135) at android.app.ActivityThread.main(ActivityThread.java:5254) at java.lang.reflect.Method.invoke(Native Method) at java.lang.reflect.Method.invoke(Method.java:372) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:903) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:698) 05-09 09:23:24.923 9003-9003/com.example.aryan.lb_minisquad_re2 I/Process: Sending signal. PID: 9003 SIG: 9

And Here's My MainActivity.java

@Override
protected void onCreate(Bundle savedInstanceState) //TODO solve runtime problem(E/AndroidRuntime: FATAL EXCEPTION: main)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

}
TextView tvnum = (TextView) findViewById(R.id.TV_num);//creating object of TextView
 public int id = 100;//id is first number of tv num
Button btnMin = (Button) findViewById(R.id.btnMIN); //creating object of  btnMin to avoid of exceptions
  public void onbtnMinClicked()//calling onClick listener of btnMin
  {
      String num =  tvnum.getText().toString();//num is value of tvnum
      num = String.valueOf(--id);//setting num one less than self(what btnmin have to do
      tvnum.setText( num );//setting num again to the tvnum
  }
}

This cannot be solved without a stacktrace and code. So unless you supply that, as ThingyWotsit said, something went wrong — Zoe, May 09 '17 at 13:53

Basil Battikhi · Accepted Answer · 2017-05-09T14:17:10.677

1

your instantiation must be inside a method check the following and under setContentView method

TextView tvnum =null;
Button btnMin=null;
@Override
protected void onCreate(Bundle savedInstanceState) //TODO solve runtime problem(E/AndroidRuntime: FATAL EXCEPTION: main)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
 tvnum = (TextView) findViewById(R.id.TV_num);//creating object of TextView
int id = 100;//id is first number of tv num
btnMin = (Button) findViewById(R.id.btnMIN);
}

edited May 09 '17 at 14:17

answered May 09 '17 at 14:10

Basil Battikhi

2,638
1
18
34

so I can't make my variables public in onCreate method and I can't use it in onClick method. – aryan gholizadeh May 09 '17 at 14:15
Check my updated Answer, this is how you can make them public So you can use them anywhere that you want inside the class – Basil Battikhi May 09 '17 at 14:17

E/AndroidRuntime: FATAL EXCEPTION: main [dupli]

1 Answers1