title: Null reference exception happen when calling buttons or textView from other activity in android
body: <p>here is the code that i used:</p>
  
  <pre><code>        try {
          Toast.makeText(getApplicationContext(),
                  "The application language now is English",
                  Toast.LENGTH_LONG).show();
  
          setContentView(R.layout.activity_main);
          welcomeTextView = (TextView) findViewById(R.id.Welcome_Text_View);
          welcomeTextView.setText(R.string.WelcomeTextView_1);
          Album_Button = (Button) findViewById(R.id.Album_Button);
          About_us_Button = (Button) findViewById(R.id.About_Us_Button);
          Contact_us_Button = (Button) findViewById(R.id.Contact_Us_Button);
          Exit_Button = (Button) findViewById(R.id.Exit_Button);
          Contact_us_Text = (TextView) findViewById(R.id.contact_us_text_view);
          Album_Button.setText(R.string.AlbumButton_1);
          About_us_Button.setText(R.string.AboutUsButton_1);
          Contact_us_Button.setText(R.string.ContactUsButton_1);
          Exit_Button.setText(R.string.Exit_Text_1);
  
          Contact_us_Text = (TextView) findViewById(R.id.contact_us_text_view);
          about_us_Text = (TextView) findViewById(R.id.About_Us_Text_View);
          Contact_us_Text.setText(R.string.Contact_Us_Text_1);
          about_us_Text.setText(R.string.About_Us_Text_1);
      }
  
      catch (Exception ex) {
          Toast.makeText(getApplicationContext(), ex.toString(),
                  Toast.LENGTH_LONG).show();
      }
  </code></pre>
  
  <p>what i am trying to do is to change the value of buttons text and textview text from another activity whenever i try to access these controls the compiler run into Null Pointer exception... can any one help me?</p>