샘플 예제 : 버튼 클릭시 글자 변경 출력과 메뉴-옵션

public class Hello extends Activity {
 
 SharedPreferences preferences;
 private EditText text;
 
 // onCreate(Bundle) is where you initialize
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
     
        super.onCreate(savedInstanceState);
           
        // setContentView(int) with a layout resource defining your UI
        setContentView(R.layout.main);
       
       
        // findViewById(int) to retrieve the widget int
        // that UI that you need to interact with programmatically
        text = (EditText)findViewById(R.id.EditText01);   
        text.setText("눌린 버튼이 없습니다.");
       
        Button button = (Button)findViewById(R.id.Button04);

        // init preference
        preferences =
            PreferenceManager.getDefaultSharedPreferences(this);

        button.setOnClickListener(new OnClickListener(){
         @Override
         public void onClick(View v){
          String username = preferences.getString("username", "n/a");
          String password = preferences.getString("password", "n/a");

          Toast.makeText(Hello.this, "U: "+username+
          " P:  "+password, Toast.LENGTH_LONG).show();
         }
        }); // setOnClickListener
  
    }

 // XML을 통해서 버튼과 연결된다.
    public void myClickHandler(View view)
    {
     switch(view.getId())
     {
     case R.id.Button01:
      text.setText("첫번째 버튼 눌림");
      break;
     case R.id.Button02:
      text.setText("두번째 버튼 눌림");
      break;
     case R.id.Button03:
      text.setText("세번째 버튼 눌림");
      break;
     }
    }

    // 메뉴 생성후에 추가
    @Override
    public boolean onCreateOptionsMenu(Menu menu)
    {
     MenuInflater inflater = getMenuInflater();
     inflater.inflate(R.menu.menu, menu);
     return true;
    }

    //메뉴아이템 생성후에 추가
    @Override
    public boolean onOptionsItemSelected(MenuItem item)
    {
     switch(item.getItemId())
     {
     case R.id.preferences:
      Intent i = new Intent(Hello.this,Preferences.class);
      startActivity(i);

      Toast.makeText(Hello.this,"관리할수",
              Toast.LENGTH_LONG).show();
      break;
     }
     return true;
    }
   
}

public class Preferences extends PreferenceActivity {
 @Override
 public void onCreate(Bundle savedInstanceState)
 {
  super.onCreate(savedInstanceState);
  addPreferencesFromResource(R.xml.preferences);
 }
}