Android OnClickListener Not Working

Question

I wrote a simple code for adding two numbers. But whenever I use the button OnClickListener() function the app is crashing.

import android.support.v7.app.ActionBarActivity;
import android.widget.Button;
import android.widget.TextView;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.widget.EditText;


public class MainActivity extends ActionBarActivity {
    Button button1; 
    EditText txtbox1,txtbox2; 
    TextView tv; 
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        txtbox1 = (EditText) findViewById(R.id.editText1);
        txtbox2 = (EditText) findViewById(R.id.editText2);
        button1 = (Button) findViewById(R.id.button1);
        tv = (TextView) findViewById(R.id.textView1);
        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                .add(R.id.container, new PlaceholderFragment()).commit();
        }

    button1.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v) { 
        String a,b; 
                    Integer vis; 
                    a = txtbox1.getText().toString(); 
                    b = txtbox2.getText().toString(); 
                    vis = Integer.parseInt(a)+Integer.parseInt(b); 
                    tv.setText(vis.toString()); 
            }
    });
}

So to check what was wrong I changed the code in button1.setOnClickListener to a simple just changing the textview to some random text. Still the app is crashing. So I guess the problem is in my button function only.

Here is my xml file as well.

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#FFFFFF"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.chawla.MainActivity$PlaceholderFragment" >

<EditText
    android:id="@+id/editText1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:hint="@string/edit_text1"
     />

<Button
    android:id="@+id/button1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/editText1"
    android:layout_below="@+id/editText1"
    android:layout_marginTop="81dp"
    android:text="@string/button_text" 
    android:clickable="true"
    />

<EditText
    android:id="@+id/editText2"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:layout_alignLeft="@+id/editText1"
    android:layout_below="@+id/editText1"
    android:layout_marginTop="18dp"
    android:ems="10"
    android:hint="@string/edit_text2" />

<TextView
    android:id="@+id/textView1"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_below="@+id/button1"
    android:layout_centerHorizontal="true"
    android:layout_marginTop="98dp"
    android:text="hi" />

Here is the stacktrace

06-04 18:24:35.150: E/AndroidRuntime(12289): FATAL EXCEPTION: main
06-04 18:24:35.150: E/AndroidRuntime(12289): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.chawla/com.example.chawla.MainActivity}: java.lang.NullPointerException
06-04 18:24:35.150: E/AndroidRuntime(12289):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2304)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2354)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at android.app.ActivityThread.access$600(ActivityThread.java:153)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1247)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at android.os.Handler.dispatchMessage(Handler.java:99)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at android.os.Looper.loop(Looper.java:137)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at android.app.ActivityThread.main(ActivityThread.java:5228)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at java.lang.reflect.Method.invokeNative(Native Method)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at java.lang.reflect.Method.invoke(Method.java:511)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:561)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at dalvik.system.NativeStart.main(Native Method)
06-04 18:24:35.150: E/AndroidRuntime(12289): Caused by: java.lang.NullPointerException
06-04 18:24:35.150: E/AndroidRuntime(12289):    at com.example.chawla.MainActivity.onCreate(MainActivity.java:35)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at android.app.Activity.performCreate(Activity.java:5213)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
06-04 18:24:35.150: E/AndroidRuntime(12289):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2258)
06-04 18:24:35.150: E/AndroidRuntime(12289):    ... 11 more

Thanks in Advance

http://stackoverflow.com/questions/23653778/nullpointerexception-accessing-views-in-oncreate. possible duplicate — Raghunandan, Jun 04 '14 at 12:39
@Android-Developer No stack trace there. No error is being given. The app crashes. — user3481478, Jun 04 '14 at 12:46
@user3481478 what seems different. Your views belong to fragment layout and its certainly looks like a duplicate of that — Raghunandan, Jun 04 '14 at 12:48
@user3481478 if the app crashes, it should be a stacktrace in LogCat, so post it here. — hardartcore, Jun 04 '14 at 12:49
and just remove the + at the xml: android:layout_below="@+id/button1". Everywhere You wrote this it has to be for example layout_below="@id/button1"... — Opiatefuchs, Jun 04 '14 at 12:56
@user3481478 initialize your views in `onCreateView` of Fragment. The views belong to Fragment — Raghunandan, Jun 04 '14 at 13:08
@Raghunandan Whats the meaning of LayoutInflater, inflater? Seems I am missing something. The video lectures doesnt include any of this. Would be glad if you provide me a link from which I can study. — user3481478, Jun 04 '14 at 13:57
@user3481478 read the docs. that is best tutorial for a beginner — Raghunandan, Jun 04 '14 at 14:46

wissem46 · Answer 1 · 2014-06-04T13:20:26.860

0

you should remove this line from xml if you are implementing your own OnclickListener in your class:

      android:clickable="true"

i got the same problem , and that was the main reason.

edited Jun 04 '14 at 13:20

answered Jun 04 '14 at 13:13

wissem46

393
3
5
14

Naa Same error coming – user3481478 Jun 04 '14 at 13:49

Android OnClickListener Not Working

1 Answers1