title: Dynamically set text in a TextView inside a Layout - Android
body: <p>I have this layout, containing a single <code>TextView</code>, but I would like to be able to change it's content (the text to be visualized) in a dynamic way, using java code.</p>
  
  <pre><code>&lt;LinearLayout
  
      xmlns:android="http://schemas.android.com/apk/res/android"
      android:orientation="horizontal"
      android:layout_width="fill_parent"
      android:layout_height="fill_parent"&gt;
  
       &lt;TextView 
  
          android:id="@+id/list_header"
          android:layout_width="fill_parent"
          android:layout_height="fill_parent"
          android:gravity="center_vertical"
          android:layout_alignParentTop="true"
          android:layout_alignParentBottom="true"
          android:textStyle="bold"
          android:textSize="22dp"
          android:textColor="#FFFFFF"
          android:padding="10dp"
          android:background="#336699" 
  
       /&gt;
  
  &lt;/LinearLayout&gt;
  </code></pre>
  
  <p>As you can see I have not defined the <code>android:text="blablabla"</code> cause it is not fixed at the point of the code in which I use it.</p>
  
  <p>I would like some method such as:</p>
  
  <pre><code>TextView headerValue = (TextView) findViewById(R.id.list_header);
  headerValue.setText( "blablabla" );
  </code></pre>
  
  <p>but this won't work because I use this layout for defining the style of a header of the list, and these lines conflict with the following I need to use:</p>
  
  <pre><code>View header = (View)getLayoutInflater().inflate(R.layout.list_header_layout, null);
  listView.addHeaderView(header);
  </code></pre>
  
  <p>Can you please help me fix this problem?</p>
  
  <hr>
  
  <p><strong>LOGCAT:</strong></p>
  
  <pre><code>E/AndroidRuntime( 1468):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
  E/AndroidRuntime( 1468):    at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1981)
  E/AndroidRuntime( 1468):    at android.app.ActivityThread.access$600(ActivityThread.java:123)
  E/AndroidRuntime( 1468):    at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1147)
  E/AndroidRuntime( 1468):    at android.os.Handler.dispatchMessage(Handler.java:99)
  E/AndroidRuntime( 1468):    at android.os.Looper.loop(Looper.java:137)
  E/AndroidRuntime( 1468):    at android.app.ActivityThread.main(ActivityThread.java:4424)
  E/AndroidRuntime( 1468):    at java.lang.reflect.Method.invokeNative(Native Method)
  E/AndroidRuntime( 1468):    at java.lang.reflect.Method.invoke(Method.java:511)
  E/AndroidRuntime( 1468):    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:784)
  E/AndroidRuntime( 1468):    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:551)
  E/AndroidRuntime( 1468):    at dalvik.system.NativeStart.main(Native Method)
  E/AndroidRuntime( 1468): Caused by: java.lang.RuntimeException: Unable to start activity ComponentInfo{com.DVA_HLUI/com.DVA_HLUI.DVA_HLUISuperviseActivity}: java.lang.NullPointerException
  E/AndroidRuntime( 1468):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1956)
  E/AndroidRuntime( 1468):    at android.app.ActivityThread.startActivityNow(ActivityThread.java:1797)
  E/AndroidRuntime( 1468):    at android.app.LocalActivityManager.moveToState(LocalActivityManager.java:135)
  E/AndroidRuntime( 1468):    at android.app.LocalActivityManager.startActivity(LocalActivityManager.java:347)
  E/AndroidRuntime( 1468):    at android.widget.TabHost$IntentContentStrategy.getContentView(TabHost.java:682)
  E/AndroidRuntime( 1468):    at android.widget.TabHost.setCurrentTab(TabHost.java:346)
  E/AndroidRuntime( 1468):    at android.widget.TabHost.addTab(TabHost.java:236)
  E/AndroidRuntime( 1468):    at com.DVA_HLUI.DVA_HLUIActivity.onCreate(DVA_HLUIActivity.java:41)
  E/AndroidRuntime( 1468):    at android.app.Activity.performCreate(Activity.java:4465)
  E/AndroidRuntime( 1468):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
  E/AndroidRuntime( 1468):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
  E/AndroidRuntime( 1468):    ... 11 more
  E/AndroidRuntime( 1468): Caused by: java.lang.NullPointerException
  E/AndroidRuntime( 1468):    at com.DVA_HLUI.DVA_HLUISuperviseActivity.onCreate(DVA_HLUISuperviseActivity.java:41)
  E/AndroidRuntime( 1468):    at android.app.Activity.performCreate(Activity.java:4465)
  E/AndroidRuntime( 1468):    at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1049)
  E/AndroidRuntime( 1468):    at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1920)
  E/AndroidRuntime( 1468):    ... 21 more
  </code></pre>
  
  <hr>
  
  <p><strong>Activity Class:</strong></p>
  
  <pre><code>public class MyActivity extends ListActivity 
  {
  
      @Override
      protected void onCreate(Bundle savedInstanceState) 
      { 
  
          super.onCreate(savedInstanceState);
          setContentView(R.layout.list_activity);
  
          ListView listView = (ListView) findViewById(android.R.id.list);
  
          listEntryClass listEntries[] = new listEntryClass[]
          {
              new listEntryClass( "bla", "bla"),
              new listEntryClass( "bla", "bla" )
          };
  
          listEntryArrayAdapter adapter = new listEntryArrayAdapter(this, R.layout.list_entry_layout, listEntries);
  
          TextView headerValue = (TextView) findViewById(R.id.list_header);
          headerValue.setText( this.getString(R.string.headerSupervise) );
  
          View header = (View)getLayoutInflater().inflate(R.layout.list_header_layout, null);
          listView.addHeaderView(header);
          listView.setAdapter(adapter);
  }
  </code></pre>