Question

I am programming a twitter app. I am making a search bar for usernames/hashtags, and I am having some trouble adding views generated from XML to the currently existing LinearLayout.

here is Search.java

public class Search extends Activity{

String searchType = "username";

public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_search);

    EditText t = (EditText)findViewById(R.id.search_content);
    t.setOnClickListener(onClickSearch);
    t.setWidth(225);

    Button b = (Button)findViewById(R.id.search_button_search);
    b.setOnClickListener(onClickButton);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    getMenuInflater().inflate(R.menu.activity_search, menu);
    return true;
}

OnClickListener onClickSearch = new OnClickListener(){

    public void onClick(View v) {
        EditText searchContent = (EditText)findViewById(R.id.search_content);
        EditText clickedContent = (EditText)v;
        if((EditText)findViewById(R.id.search_content) == (EditText)v){
            EditText t = (EditText)v;
            t.setText("");
        }

        //EditText searchContent = (EditText)findViewById(R.id.search_content);
        //EditText clickedContent = (EditText)v;

        /*if((Button)v == (Button)findViewById(R.id.search_button_type)){
            EditText t = (EditText)findViewById(R.id.search_content);
            Search.this.searchByUserName(t.getText().toString());
        }

        if((Button)v == (Button)findViewById(R.id.search_button_search)){

        }*/
    }

};

OnClickListener onClickButton = new OnClickListener(){

    public void onClick(View v) {
        //if((Button)v == (Button)findViewById(R.id.search_button_search)){
            EditText t = (EditText)findViewById(R.id.search_content);
            Search s = new Search();
            s.searchByUserName(t.getText().toString());
        //}

        //if((Button)v == (Button)findViewById(R.id.search_button_search)){

        //}
    }

};

public void searchByUserName(String userName){
    //System.out.println("beginning->searchByUserName");
    TwitterHandler handler = new TwitterHandler();
    List<View> views = handler.queryUserName(userName, this);

    LinearLayout ll = (LinearLayout)findViewById(R.id.search_panel);
    for(int i = 0; i < views.size(); i++){
        ll.addView(views.get(i));
    }
}

}

here is the XML

<LinearLayout 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:id="@+id/search_panel" >
    <Button
       android:id="@+id/search_button_type"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Search Type"/>

    <EditText
        android:id="@+id/search_content"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Search Here" >
    </EditText>

    <Button
        android:id="@+id/search_button_search"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Search"/>
</LinearLayout>

My LogCat is telling me there is a NullPointerException, the process is forced to quit on the android virtual device. Please Help!!!

Here is the TwitterHandler

public class TwitterHandler extends DefaultHandler{
private final String USER_SEARCH = "https://api.twitter.com/1/users/lookup.xml?screen_name=";

public List<View> queryUserName(String userName, Context context){
    System.out.println("beginning->queryUserName");
    String url = USER_SEARCH + userName;
    //ListView view = new ListView(context);
    List<View> views = new ArrayList<View>();
    Document doc = null;
    DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
    try {
        System.out.println("in try statement->queryUserName");
        DocumentBuilder db = dbf.newDocumentBuilder();

        InputSource is = new InputSource();
        is.setCharacterStream(new StringReader(url));
        doc = db.parse(is); 

        NodeList nl = doc.getChildNodes();

        for(int i = 0; i < nl.getLength(); i++){
            Element e = (Element)nl.item(i);
            TextView t = new TextView(context);

            String name = "";
            String screenName = "";
            Bitmap bitmap = null;

            Node n = (Node)e.getChild("name");
            name = n.getTextContent();
            t.setText(name);
            views.add(t);

            t = new TextView(context);
            n = (Node)e.getChild("screen_name");
            screenName = n.getTextContent();
            t.setText(screenName);
            views.add(t);

            n = (Node)e.getChild("profile_image_url");
            bitmap = getBitmap(n.getTextContent());
            ImageView imageView = new ImageView(context);
            imageView.setImageBitmap(bitmap);
            views.add(imageView);

        }

    }catch(Exception e){ }
    return views;
}

private Bitmap getBitmap(String imageUrl) throws IOException{
InputStream inputStream = null;
 URL u = new URL(imageUrl);
 URLConnection conn = u.openConnection();

 try{
      HttpURLConnection httpConn = (HttpURLConnection)conn;
      httpConn.setRequestMethod("GET");
      httpConn.connect();

      if (httpConn.getResponseCode() == HttpURLConnection.HTTP_OK) {
          inputStream = httpConn.getInputStream();
      }
 }
 catch (Exception ex) { }

return BitmapFactory.decodeStream(inputStream);

}

}

Here is the Log

07-26 17:00:24.523: D/AndroidRuntime(335): Shutting down VM
07-26 17:00:24.523: W/dalvikvm(335): threadid=1: thread exiting with uncaught exception     (group=0x40015560)
07-26 17:00:24.533: E/AndroidRuntime(335): FATAL EXCEPTION: main
07-26 17:00:24.533: E/AndroidRuntime(335): java.lang.ClassCastException:   java.util.AbstractList$SubAbstractListRandomAccess
07-26 17:00:24.533: E/AndroidRuntime(335):  at    com.example.twitter.viewer.Search.searchByUserName(Search.java:84)
07-26 17:00:24.533: E/AndroidRuntime(335):  at com.example.twitter.viewer.Search$2.onClick(Search.java:71)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.view.View.performClick(View.java:2485)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.view.View$PerformClick.run(View.java:9080)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.os.Handler.handleCallback(Handler.java:587)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.os.Handler.dispatchMessage(Handler.java:92)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.os.Looper.loop(Looper.java:123)
07-26 17:00:24.533: E/AndroidRuntime(335):  at android.app.ActivityThread.main(ActivityThread.java:3683)
07-26 17:00:24.533: E/AndroidRuntime(335):  at java.lang.reflect.Method.invokeNative(Native Method)
07-26 17:00:24.533: E/AndroidRuntime(335):  at java.lang.reflect.Method.invoke(Method.java:507)
07-26 17:00:24.533: E/AndroidRuntime(335):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
07-26 17:00:24.533: E/AndroidRuntime(335):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
07-26 17:00:24.533: E/AndroidRuntime(335):  at dalvik.system.NativeStart.main(Native Method)

Answer 1

You are trying to make a new Instance Object of your Search Activity.
In which your contentView is not available, so you can not define LinearLayout at searchByUserName method.

Instead just simple use method name..

So Replace these lines,

Search s = new Search();
s.searchByUserName(t.getText().toString());

with only,

searchByUserName(t.getText().toString());