CODEWITHSUNDEEP
androidandroid-button
user1137313
user1137313

Reputation: 2410

Android Button onClick listener error

This is ridiculous , I have a simple activity inside my project, with a button and some spinners. In onCreate of the activity, I want to set the onClick event for the button (just like I do for other activities in my project. But for some unknown reasons I gen an error when creating the activity that refers to the line with the setOnClickListener. If I comment the entire listener stuff, the activity works so it's all there in the On Click listener declaration. Here is my code:

 protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
        setContentView(R.layout.activity_send_msg);

        final Button btn_rev = (Button) findViewById(R.id.btn_reveniremsg);
        btn_rev.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                finish();
            }
        });

(The error will point to the line with final Button btn_rev... of the above code)

And now the Logat:

W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0xa62d9288)
E/AndroidRuntime﹕ FATAL EXCEPTION: main
    java.lang.RuntimeException: Unable to start activity ComponentInfo{app_pathmyblabla./activitymyblabla._path}: java.lang.NullPointerException
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2059)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
            at android.app.ActivityThread.access$600(ActivityThread.java:130)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4745)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)
     Caused by: java.lang.NullPointerException
            at myblabla.app.SendMsgActivity.onCreate (SendMsgActivity.java:32)
            at android.app.Activity.performCreate(Activity.java:5008)
            at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1079)
            at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2023)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2084)
            at android.app.ActivityThread.access$600(ActivityThread.java:130)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1195)
            at android.os.Handler.dispatchMessage(Handler.java:99)
            at android.os.Looper.loop(Looper.java:137)
            at android.app.ActivityThread.main(ActivityThread.java:4745)
            at java.lang.reflect.Method.invokeNative(Native Method)
            at java.lang.reflect.Method.invoke(Method.java:511)
            at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
            at dalvik.system.NativeStart.main(Native Method)
            I/Process﹕ Sending signal. PID: 5821 SIG: 9

And the line with the blue color is at myblabla.app.SendMsgActivity.onCreate (SendMsgActivity.java:32)

The row that the blue link points to is the first line of my code above.

What is going on? I had automatically generated the code of the clickListener, it was generated by the IDE (Android Studio). I just added finish(); inside the onClick.

Also, I have the same listener code in other activities, and they work just fine

Please tell me what I am doing wrong.

XML of the layout

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context="mypack.app.SendMsgActivity"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="10dp">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/imageView"
            android:src="@drawable/abc_spinner_ab_focused_holo_light" />

        <RelativeLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_gravity="right"
            android:gravity="right">

            <Button
                style="?android:attr/buttonStyleSmall"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Renunta"
                android:id="@+id/button"
                android:layout_gravity="right"
                android:gravity="right|end|fill_vertical" />
        </RelativeLayout>
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:id="@+id/linearLayout">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Titlu mesaj"
            android:id="@+id/textView" />

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/editText"
            android:layout_weight="1" />
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/linearLayout3">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Continut mesaj:"
            android:id="@+id/textView3"
            android:layout_gravity="center_vertical"
            android:layout_alignBottom="@+id/editText2"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" />

        <EditText
            android:layout_width="480dp"
            android:layout_height="wrap_content"
            android:inputType="textMultiLine"
            android:ems="10"
            android:id="@+id/editText2"
            android:layout_gravity="center_vertical"
            android:layout_below="@+id/linearLayout2"
            android:layout_alignParentRight="true"
            android:layout_alignParentEnd="true"
            android:layout_toRightOf="@+id/textView3" />
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/linearLayout"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:id="@+id/linearLayout2">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Destinatie mesaj"
            android:id="@+id/textView2" />

        <Spinner
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/spinnertipdest"
            android:entries="@array/tipuridestinatie"
            android:prompt="@string/tipdest_prompt"
            android:layout_weight="1" />
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Alege reprezentant"
            android:id="@+id/lbl_destinatie" />

        <Spinner
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/spinneruzer"
            android:layout_weight="1" />
    </LinearLayout>

</LinearLayout>

Thank you

Upvotes: 0

Views: 2156

Answers (3)

navjotdhanawat
navjotdhanawat

Reputation: 333

your code 

final Button btn_rev = (Button) findViewById(R.id.btn_reveniremsg);

It must be

final Button btn_rev = (Button) findViewById(R.id.button);

Upvotes: 1

RobertM
RobertM

Reputation: 297

This xml will work:

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context="mypack.app.SendMsgActivity"
    android:orientation="vertical"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:padding="10dp">

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content">

        <ImageView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/imageView"
            android:src="@drawable/abc_spinner_ab_focused_holo_light" />

        <RelativeLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:layout_gravity="right"
            android:gravity="right">

            <Button
                style="?android:attr/buttonStyleSmall"
                android:layout_width="wrap_content"
                android:layout_height="wrap_content"
                android:text="Renunta"
                android:id="@+id/btn_reveniremsg"
                android:layout_gravity="right"
                android:gravity="right|end|fill_vertical" />
        </RelativeLayout>
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:id="@+id/linearLayout">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Titlu mesaj"
            android:id="@+id/textView" />

        <EditText
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/editText"
            android:layout_weight="1" />
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/linearLayout3">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Continut mesaj:"
            android:id="@+id/textView3"
            android:layout_gravity="center_vertical"
            android:layout_alignBottom="@+id/editText2"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" />

        <EditText
            android:layout_width="480dp"
            android:layout_height="wrap_content"
            android:inputType="textMultiLine"
            android:ems="10"
            android:id="@+id/editText2"
            android:layout_gravity="center_vertical"
            android:layout_below="@+id/linearLayout2"
            android:layout_alignParentRight="true"
            android:layout_alignParentEnd="true"
            android:layout_toRightOf="@+id/textView3" />
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/linearLayout"
        android:layout_alignParentRight="true"
        android:layout_alignParentEnd="true"
        android:id="@+id/linearLayout2">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Destinatie mesaj"
            android:id="@+id/textView2" />

        <Spinner
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/spinnertipdest"
            android:entries="@array/tipuridestinatie"
            android:prompt="@string/tipdest_prompt"
            android:layout_weight="1" />
    </LinearLayout>

    <LinearLayout
        android:orientation="horizontal"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent">

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Alege reprezentant"
            android:id="@+id/lbl_destinatie" />

        <Spinner
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:id="@+id/spinneruzer"
            android:layout_weight="1" />
    </LinearLayout>

</LinearLayout>

Upvotes: 1

Blo
Blo

Reputation: 11988

Your Button has this id: 

android:id="@+id/button"

and it's the cause of your NullPointerException. Try this set the right id as follows: 

Button btn_rev = (Button) findViewById(R.id.button);

Upvotes: 4

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