title: How to make a button unclickable
body: <p>So right now i am having trouble making the next button unclickable when it is on the last page of the activity. As of right now it goes back to the first screen. How do i make it so that it know when to grey out the button or make it unclickable when the user gets to the last screen.</p>
  
  <p>Here is my code: </p>
  
  <pre><code>public class ReadingActivity extends Activity implements OnClickListener {
  
      private ViewFlipper viewFlipper;
      Button btnNext, btnPrev;
      private float lastX;
  
      /** Called when the activity is first created */
  
      @Override
      protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.reading);
          viewFlipper=(ViewFlipper)findViewById(R.id.view_flipper);
          btnNext=(Button)findViewById(R.id.btnNext);
          btnPrev=(Button)findViewById(R.id.btnPre);
  
  
          btnNext.setOnClickListener(this);
          btnPrev.setOnClickListener(this);
  
          btnNext.setEnabled(true);
      }
  
  
  
      @Override
      public void onClick(View arg0) {
          // TODO Auto-generated method stub
  
          switch(arg0.getId()){
          case R.id.btnNext:
              viewFlipper.setInAnimation(this, R.anim.in_from_right);
              viewFlipper.setOutAnimation(this, R.anim.out_to_left);
              viewFlipper.showNext();
              break;
          case R.id.btnPre:
              viewFlipper.setInAnimation(this, R.anim.in_from_left);
              viewFlipper.setOutAnimation(this, R.anim.out_to_right);
              viewFlipper.showPrevious();
              break;
          }
  
      }
  
  
  }
  </code></pre>