How to set a background image in android

Question

Im very new to this android development.I just started to create a hello world application.

I tried to set a background image and it is working fine.When i tried to add a text on the image it is not working.

I tried in the way below.Can anyone please help me where im going wrong.

in

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" 
    android:background="@drawable/andriod" 
    android:layout_gravity="center_vertical" 
    android:gravity="center_vertical"> 

    <TextView
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />

</LinearLayout>

HelloActivity.java

  import android.app.Activity;
  import android.os.Bundle;
  import android.widget.TextView;
  //import android.widget.ImageView;    

    public class HelloActivity extends Activity {
    //    /** Called when the activity is first created. */
    //    @Override
    //    public void onCreate(Bundle savedInstanceState) {
    //        super.onCreate(savedInstanceState);
    //        setContentView(R.layout.main);
    //    }    

    /** Called when the activity is first created. */
       @Override

       public void onCreate(Bundle savedInstanceState) {
           super.onCreate(savedInstanceState);

           TextView tv = new TextView(this);              
           tv.setText("This is the first andorid app");          
           setContentView(R.layout.main);         
       }
}

When running it is showing the background image but "This is the first andorid app" is not showing.

Hoping for your help

Answer 1

First you need to give the textview an id in XML file, so that it can be accessed in the Java source (note the android:id attribute in following 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" 
    android:background="@drawable/andriod" 
    android:layout_gravity="center_vertical" 
    android:gravity="center_vertical"> 

    <TextView
        android:id="@+id/textView"

        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:text="@string/hello" />

</LinearLayout>

Now set the text in this textview;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    TextView textView = (TextView) findViewId(R.id.textView);

    textView.setText("This is the first andorid app");
}

Note, how the textview declared in XML is accessed from here.

It is not

TextView textView = new TextView(this);

this will create a new textview. But what we need here is

TextView textView = (TextView) findViewId(R.id.textView);

this will refer to the textview declared in XML file above.

Answer 2

You need to fetch the TextView from the current content view .. add these lines after setContentView(..), also add an id to your text view in the layout

TextView tv = (TextView)findViewById(...)