Android Changing xml

Question

Hello I want to change text in my textView , but dont know how. I tryed to change it like this

TextView textView3 = (TextView) findViewById(R.id.textView3);
textView3.append("hi");

But this textView is in another xml-file.

the compiler outputs

FATAL EXCEPTION: main
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.nividimka.shopapplication/com.example.nividimka.shopapplication.ShopActivity}: java.lang.NullPointerException
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2351)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2403)
at android.app.ActivityThread.access$600(ActivityThread.java:165)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1373)
at android.os.Handler.dispatchMessage(Handler.java:107)
at android.os.Looper.loop(Looper.java:194)
at android.app.ActivityThread.main(ActivityThread.java:5391)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.example.nividimka.shopapplication.ShopActivity.onCreate(ShopActivity.java:62)
at android.app.Activity.performCreate(Activity.java:5122)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1150)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2315)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2403) 
at android.app.ActivityThread.access$600(ActivityThread.java:165) 
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1373) 
at android.os.Handler.dispatchMessage(Handler.java:107) 
at android.os.Looper.loop(Looper.java:194) 
at android.app.ActivityThread.main(ActivityThread.java:5391) 
at java.lang.reflect.Method.invokeNative(Native Method) 
at java.lang.reflect.Method.invoke(Method.java:525) 
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833) 
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600) 
at dalvik.system.NativeStart.main(Native Method)

score 0 · Answer 1 · answered Nov 28 '15 at 06:43

0

There's no textview with id R.id.textView3, so findViewById returns null. Are you sure you've called setContentView, or the layout is attached to your activity?

answered Nov 28 '15 at 06:43

UtsavShah

857
1
9
20

Blue_Alien · Accepted Answer · 2015-11-28T07:13:16.033

the question is not clear, but i believe you are trying to update the text of a TextView which is on another activity/previous. Then you may declare the TextView as public static in the class where the actual layout file(containing textview) inflated.

Class PreviousActivity extends Activity{
     public static TextView textView3 ;


// inside onCreate(), after setContentView()
//initialize to avoid null-pointer.
textView3 = (TextView) findViewById(R.id.textView3);
}

then you can try from otherActivity.

PreviousActivity.textView3 .append("new txt");

Android Changing xml

2 Answers2