Access TextView from another class

Question

I have my main boot class loading main.xml, but I'm trying to figure out how to access a TextView from another class that loads information from a database. I would like to publish this information in a TextView.

So far, I have not found useful examples on Google.

EDIT: This is my class that does the database work:

import android.widget.TextView;import android.view.View; public class DBWork{ private View view; ... TextView tv = (TextView) view.findViewById(R.id.TextView01); tv.setText("TEXT ME") 

However, every time I do this, I get a nullpointerexception

Answer 1

If I were you, I would save all your UI updates in your main Activity class. You simply get your DBWork class to return the text you want to display to your Activity . So something like:

 public class Main extends Activity { @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.main); TextView tv = (TextView) view.findViewById(R.id.TextView01); DBWork db = new DBWork("192.168.2.14:8080/DH/DPost";, "test_db"); tv.setText(db.getText()); } } 

Then your db class:

 public class DBWork{ ... public String getText(){ //do stuff return ""; } } 

Please note that any database operations that you perform during onCreate should be as fast as possible, as they work in the user interface thread. If you intend to make lengthy database queries, you should use AsyncTask or create a new Thread and use Handler to update the user interface.

Answer 2

You should use LayoutInflater:

  LayoutInflater inflater = getLayoutInflater(); View myView = inflater.inflate(R.layout.main, null); TextView myTextView = (TextView) findViewById(R.id.myTextViewInXml); 

Answer 3

You can pass links to all of your controls after you instantiate the class. I personally pass the entire class that has all the controls as public variables.

Answer 4

You must define your TextView using xml and assign it an identifier. Example:

 <TextView android:layout_width="wrap_content" android:layout_height="match_parent" android:textColor="#FFF" android:gravity="center_vertical|right" android:paddingLeft="5dip" android:paddingRight="5dip" android:text="@string/name" android:id="@+id/myTextViewInXml"/> 

Then you can access it in each class using

  TextView myTextView = (TextView) findViewById(R.id.myTextViewInXml); 

Answer 5

Right:

  LayoutInflater inflater = getLayoutInflater(); View myView = inflater.inflate(R.layout.main, null); TextView myTextView = (TextView) findViewById(R.id.myTextViewInXml); 

But before you specify which file you want to use:

setContentView (XML file identifier that includes R.id.myTextViewInXml)

Without this, findViewById(R.id.myTextViewInXml); will always return null .

This is an example:

 public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.virtualtour); // before !! progress_bar = (ProgressBar) findViewById(R.id.vt_progress); loading_ly = (RelativeLayout) findViewById(R.id.vt_layout_loading); panorama_description = (TextView) findViewById(R.id.vt_description); virtualtour_relatively = (RelativeLayout) findViewById(R.id.vt_layout_opengl); ......... 

Answer 6

 TextView bt1 =m_activity.findViewById(R.id.textview1); 

In the above example, where view bt1 belongs to another class. You can access bt1 with an instance of the class and get the identifier. Now do what you want to do with the bt1 instance.

Note. Make Sure bt1 public in another class