android hello world app help
<p>i am learning android apps and i made this app and it doesnt work</p>

<pre><code>  package com.android.test;

  import android.app.Activity;
  import android.os.Bundle;
  import android.view.View;
  import android.view.View.OnClickListener;
  import android.widget.Button;
  import android.widget.Toast;

  public class HelloWorld extends Activity {
      /** Called when the activity is first created. */
      @Override
      public void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.main);
          Button button = (Button) findViewById(R.id.Button01);
          button.setOnClickListener(new OnClickListener() {
              @Override
              public void onClick(View v) {
                  Toast.makeText(HelloWorld.this, "Hello World", Toast.LENGTH_SHORT).show();
              }
          });
      }
  }
</code></pre>

<p>but it doesnt work!!! please tell me what is wrong and help me to solve it!1</p>
