我用android手机向arduino发送信息出现fatal exception main java.lang.nullpointerexception错误

我用android手机向arduino发送信息出现fatal exception main java.lang.nullpointerexception错误​

android程序在我手机上总是崩溃，程序运行日志显示错误在以下紫色部分处，存在java.lang.nullPointerException异常，导致每次准备打开电灯时程序都会崩溃。

else{
btout.write("1".getBytes());
btout.flush();
lightButton.setImageResource(R.drawable.light_open);
lightStatus = true;
}
问了很多人都不知道该怎么解决，我刚刚接触android和arduino实在是没有办法了。希望各位大神能够帮帮我，谢谢了。我把错误日志放在最后了。我用的开发环境是直接从官方网站下载的adt-bundle-windows-x86-20131030，SDK版本是22.6.3，手机是android 4.0.4版本。（如果需要源程序请发信息到我邮箱：qq768135@gmail.com）

具体代码在下面：

package com.liuyongliang.smartlightingsystem;



import java.io.IOException;

import java.io.OutputStream;

import java.util.UUID;



import android.app.Activity;

import android.bluetooth.BluetoothAdapter;

import android.bluetooth.BluetoothDevice;

import android.bluetooth.BluetoothSocket;

import android.content.Intent;

import android.content.SharedPreferences;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuInflater;

import android.view.MenuItem;

import android.view.View;

import android.widget.ImageButton;

import android.widget.TextView;



public class MainActivity extends Activity {

	/** Called when the activity is first created. */



	private static final String PREF_BLUETOOTH_DEVICE_MAC = "BLUETOOTH_DEVICE_MAC";



	BluetoothAdapter localAdapter;

	BluetoothSocket lightSocket;

	OutputStream btout;

	boolean lightStatus = false;

	ImageButton lightButton;



	@Override

	public void onCreate(Bundle savedInstanceState) {



		super.onCreate(savedInstanceState);

		setContentView(R.layout.activity_main);

		TextView author = (TextView) this.findViewById(R.id.textView1);

		author.setText("再续朝圣路");

		lightButton = (ImageButton) this.findViewById(R.id.imageButton1);

		lightButton.setOnClickListener(new View.OnClickListener() {



			@Override

			public void onClick(View v) {

				// TODO Auto-generated method stub

				// if(btout!=null){



				try {

					if (lightStatus) {

						btout.write("0".getBytes());

						btout.flush();

						lightButton.setImageResource(R.drawable.light_close);

						lightStatus = false;

					} else {

						btout.write("1".getBytes());

						btout.flush();

						lightButton.setImageResource(R.drawable.light_open);

						lightStatus = true;

					}



				} catch (IOException e) {

					e.printStackTrace();

				}

				// }

			}

		});

		enableBT();



		SharedPreferences settingActivity = getPreferences(MODE_PRIVATE);

		String device_mac = settingActivity.getString(

				PREF_BLUETOOTH_DEVICE_MAC, null);

		if (device_mac == null) {

			Intent serverIntent = null;

			serverIntent = new Intent(MainActivity.this,

					DeviceListActivity.class);

			startActivityForResult(serverIntent, 1);

		} else {

			BluetoothDevice myLightDevice = localAdapter

					.getRemoteDevice(device_mac);

			connectDevice(myLightDevice);

		}

	}



	public void enableBT() {

		localAdapter = BluetoothAdapter.getDefaultAdapter();

		// If Bluetooth not enable then do it



		if (!localAdapter.isEnabled()) {

			localAdapter.enable();

			while (!(localAdapter.isEnabled())) {



			}

		}

	}



	@Override

	protected void onDestroy() {



		try {

			btout.close();

			lightSocket.close();

		} catch (IOException e) {

			e.printStackTrace();

		}

		super.onDestroy();

	}



	public void onActivityResult(int requestCode, int resultCode, Intent data) {

		switch (requestCode) {

		case 1:

			// When DeviceListActivity returns with a device to connect

			if (resultCode == Activity.RESULT_OK) {

				connectDevice(getBluetoothDevice(data, true));

			}

			break;

		}

	}



	public BluetoothDevice getBluetoothDevice(Intent data, boolean secure) {

		// Get the device MAC address

		String address = data.getExtras().getString(

				DeviceListActivity.EXTRA_DEVICE_ADDRESS);



		SharedPreferences settingActivity = getPreferences(MODE_PRIVATE);

		SharedPreferences.Editor prefEditor = settingActivity.edit();

		prefEditor.putString(PREF_BLUETOOTH_DEVICE_MAC, address);

		prefEditor.commit();

		// Get the BLuetoothDevice object

		return localAdapter.getRemoteDevice(address);

	}



	private void connectDevice(BluetoothDevice device) {



		try {

			lightSocket = device.createRfcommSocketToServiceRecord(UUID

					.fromString("00001101-0000-1000-8000-00805F9B34FB"));



			lightSocket.connect();



			if (lightSocket != null) {

				try {

					btout = lightSocket.getOutputStream();

					// btout.write("MobilePhone Connected!".getBytes());

					// btout.flush();

				} catch (IOException e) {

					e.printStackTrace();

				}

			} else {

				// Error

			}



		} catch (IllegalArgumentException e) {

			e.printStackTrace();

		} catch (IOException e) {

			e.printStackTrace();

		}

	}



	@Override

	public boolean onCreateOptionsMenu(Menu menu) {

		MenuInflater inflater = getMenuInflater();

		inflater.inflate(R.menu.main, menu);

		return true;

	}



	@Override

	public boolean onOptionsItemSelected(MenuItem item) {

		Intent serverIntent = null;

		switch (item.getItemId()) {

		case R.id.secure_connect_scan:

			// Launch the DeviceListActivity to see devices and do scan

			serverIntent = new Intent(MainActivity.this,

					DeviceListActivity.class);

			startActivityForResult(serverIntent, 1);

			return true;

		}

		return false;

	}

}