Variable values available but always show null pointer exception. How to solve it

Question

if(  str_driversig != null && str_driversig.length()>0 &&  !str_driversig.contentEquals(null))
    {
}else
    {
        Toast.makeText(context,"Please give Driver Signature",Toast.LENGTH_SHORT).show();
    }

here str_driversig variable vaue like ...../..../signature/81046.png

Always show error below:

UncaughtException: java.lang.NullPointerException: Null reference used for synchronization (monitor-enter)
   at java.lang.String.contentEquals(String.java:958)
   at com.main.exam.ui.driverchecklist.AddDriverChecklist.save_driver_checklist(AddDriverChecklist.java:1318)
   at com.main.exam.ui.driverchecklist.AddDriverChecklist.onClick(AddDriverChecklist.java:367)
   at android.view.View.performClick(View.java:6261)
   at android.widget.TextView.performClick(TextView.java:11185)
   at android.view.View$PerformClick.run(View.java:23752)
   at android.os.Handler.handleCallback(Handler.java:751)
   at android.os.Handler.dispatchMessage(Handler.java:95)
   at android.os.Looper.loop(Looper.java:154)
   at android.app.ActivityThread.main(ActivityThread.java:6776)
   at java.lang.reflect.Method.invoke(Native Method)
   at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1518)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1408)

some time value comes like "null" string . so me checked like !str_driversig.contentEquals("null") — Krishna android, Mar 12 '18 at 23:13
Possible duplicate of [What is a NullPointerException, and how do I fix it?](https://stackoverflow.com/questions/218384/what-is-a-nullpointerexception-and-how-do-i-fix-it) — Alessandro Da Rugna, Mar 13 '18 at 01:07

score 1 · Accepted Answer · answered Mar 12 '18 at 23:17

1

You are trying to check if the data string equals to null which would be through !str_driversig.contentEquals("null") and not !str_driversig.contentEquals(null). The null is causing the NPE in your case.

answered Mar 12 '18 at 23:17

Napster

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Variable values available but always show null pointer exception. How to solve it

1 Answers1