Please tell me the cause of the Android putExtra code execution error

Blockquote

int to save the value of) change and there was an error in the process by which you store the value and activity to the value of an App is forced exit in the process I think. I don't know the cause. Please let me know. Generous spacing gives healthier and value which is an error in value also went with the ID code and switching activity, the app will be forcibly shut down.

Main Activity Java

EditText editTextNo = (EditText) findViewById(R.id.editTextNo) ; String strNo = editTextNo.getText().toString() ; if (!strNo.isEmpty() && strNo.matches("^[0-9]*$")) { // check numbers by RegEx. intent.putExtra("contact_no", Integer.parseInt(strNo)) ; } } else { intent.putExtra("contact_no", 0) ; }

Contact Activity Java

TextView textNo = (TextView)findViewById(R.id.editTextNo); int num = intent.getIntExtra("contact_no",0); textNo.setText(Integer.toString(num));

< Error values >

E/AndroidRuntime: FATAL EXCEPTION: main Process: com.example.putextratest, PID: 12684 java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.putextratest/com.example.putextratest.ContactActivity}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3333) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3477) 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$H.handleMessage(ActivityThread.java:2043) at android.os.Handler.dispatchMessage(Handler.java:106) at android.os.Looper.loop(Looper.java:216) at android.app.ActivityThread.main(ActivityThread.java:7464) at java.lang.reflect.Method.invoke(Native Method) at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:549) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:955) Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.TextView.setText(java.lang.CharSequence)' on a null object reference at com.example.putextratest.ContactActivity.onCreate(ContactActivity.java:19) at android.app.Activity.performCreate(Activity.java:7990) at android.app.Activity.performCreate(Activity.java:7979) at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1309) at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3308) at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3477)  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$H.handleMessage(ActivityThread.java:2043)  at android.os.Handler.dispatchMessage(Handler.java:106)  at android.os.Looper.loop(Looper.java:216)  at android.app.ActivityThread.main(ActivityThread.java:7464)  at java.lang.reflect.Method.invoke(Native Method)  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:549)  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:955)