Programming are endless.

import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.content.Intent;
import android.os.Bundle;
import android.view.Menu;
import android.widget.Toast;

public class MainActivity extends Activity {
    // 요청코드 상수 정의
    private static final int REQUEST_ENABLE_BT = 3;
    // 객체 선언
    private BluetoothAdapter mBluetoothAdapter = null;


	@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);

        // 기기가 블루투스를 지원하는지 확인
        mBluetoothAdapter  = BluetoothAdapter.getDefaultAdapter(); 
        if(mBluetoothAdapter == null) {
        	Toast.makeText(this, "블루투스를 사용할 수 없습니다.", Toast.LENGTH_LONG).show();
        	finish();
        	return ;
        }
    }
   
	public void onStart() {
		super.onStart();
		// 블루투스가 활성화 되어 있는지 확인
		if(!mBluetoothAdapter.isEnabled()) {
			Intent enableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE); 
			startActivityForResult(enableIntent, REQUEST_ENABLE_BT);
		}
	}
   
	public void onActivityResult(int requestCode, int resultCode, Intent data) {
		switch(requestCode) {
		case REQUEST_ENABLE_BT:
			if(resultCode == Activity.RESULT_OK) {
				Toast.makeText(this, "블루투스를 활성화하였습니다.", Toast.LENGTH_LONG).show();
			} else {
				Toast.makeText(this, "블루투스를 활성화하지 못했습니다.", Toast.LENGTH_LONG).show();
			}
		}
	}
	
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }
    
}