ListView with customized items

Question

i have looked at the issue closely since you guys were so confident and i found that i have typed the incorrect layout name while i was typing in the question (sorry about that)

the correct contentview i have is this:

setContentView(R.layout.main);

End Edit

i see my id in R.Java:

public static final int txtReadMore_link=0x7f06000e;

Update:

03-19 17:05:07.158: E/AndroidRuntime(1356): java.lang.RuntimeException: Unable to start activity ComponentInfo{net.website.playlist_activity}: java.lang.NullPointerException
03-19 17:05:07.158: E/AndroidRuntime(1356):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1647)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1663)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at android.app.ActivityThread.access$1500(ActivityThread.java:117)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:931)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at android.os.Handler.dispatchMessage(Handler.java:99)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at android.os.Looper.loop(Looper.java:123)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at android.app.ActivityThread.main(ActivityThread.java:3683)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at java.lang.reflect.Method.invokeNative(Native Method)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at java.lang.reflect.Method.invoke(Method.java:507)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at dalvik.system.NativeStart.main(Native Method)
03-19 17:05:07.158: E/AndroidRuntime(1356): Caused by: java.lang.NullPointerException
03-19 17:05:07.158: E/AndroidRuntime(1356):     at net.website.playlist_activity.onCreate(playlist_activity.java:101)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
03-19 17:05:07.158: E/AndroidRuntime(1356):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1611)

i am trying to access textview from the custom listview and below is the code and i am getting null ref error... how can i access to the txtReadMore_link ?

show the new activity when the user click on the link.

playlist_activity

private TextView link;
@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.list_row);

       //throwing error - NULL????
       link = (TextView)findViewById(R.id.txtReadMore_link);

       link.setOnClickListener(new OnClickListener() {
        public void onClick(View v) {
        int duration = Toast.LENGTH_SHORT;
        TextView tx =(TextView)v.findViewById(R.id.txtReadMore_link); 
        Toast toast = Toast.makeText(playlist_activity.this, tx.getText(), duration);
        toast.show();               
        }
    });
}

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical">

    <ListView
        android:id="@+id/list"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:divider="#b5b5b5"
        android:dividerHeight="1dp"
        android:listSelector="@drawable/list_selector"></ListView>    
</LinearLayout>

list_row.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:background="@drawable/list_selector"
    android:orientation="horizontal"
    android:padding="5dip" >

    <!--  ListRow Left sied Thumbnail image -->
    <LinearLayout android:id="@+id/thumbnail" 
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="3dip"      
        android:layout_alignParentLeft="true"
        android:background="@drawable/image_bg" 
        android:layout_marginRight="5dip">

        <ImageView     
            android:id="@+id/list_image"   
            android:layout_width="50dip"
            android:layout_height="50dip"
            android:src="@drawable/rihanna"/>

    </LinearLayout>

    <!-- Title Of Song-->
    <TextView
        android:id="@+id/title"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignTop="@+id/thumbnail"
        android:layout_toRightOf="@+id/thumbnail"
        android:text="Rihanna Love the way lie"
        android:textColor="#040404"
        android:typeface="sans" 
        android:textSize="15dip"
        android:textStyle="bold"/>

    <!-- Artist Name -->
    <TextView
        android:id="@+id/artist"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/title"
        android:textColor="#343434"
        android:textSize="10dip"
        android:layout_marginTop="1dip"
        android:layout_toRightOf="@+id/thumbnail"
        android:text="Just gona stand there and ..." />


       <TextView
            android:id="@+id/txtReadMore_link"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" 
            android:layout_margin="5dp" 
            android:clickable="true"
            android:text="Click here to read more.."
            android:textSize="9sp" />



</RelativeLayout>

Answer 1

just clean your project and re run it like this : in your Eclipse IDE , click Project ==> Clean ==> Check your Project ==> Press OK . and Run again your project and it will works ;)

EDIT :

you have the NullPointerException because in your method setContentView() , you have specified the layout of your activity as : main.xml

And you are trying to find a View By id which is not in your layout main.xml ( it is on your list_row.xml) , verify that you have specified the exact layout of your Activity, or try to declare your TextView in your layout main.xml

Answer 2

You can't use findViewById() from the onCreate() method to search for a View that is in a ListView row layout. The correct way is to use a custom adapter and in the getView() method set the on click listener for that particular View. There are many question around StackOverflow regarding how to do this. Here are some tutorials:

http://www.vogella.de/articles/AndroidListView/article.html or http://commonsware.com/Android/excerpt.pdf

Answer 3

I suspect you are not setting the view you think you are for your activity, i.e. you do

setContentView(R.layout.list_row); 

in the onCreate, where you probably meant to say

setContentView(R.layout.main); 

As txtReadMore_link is on your main.xml, and not on your list_row.xml, the code will not be able to find the view and return null.