我刚用Arduino完成了一个控制房子灯光的系统。 ON和OFF的序列代码是I和O. 我正在尝试学习android编程，并使用它来处理这个项目与蓝牙。 一切正常，但当按下发送“I”或“O”的按钮时应用程序崩溃。初始化蓝牙连接的按钮也会崩溃。 这是我的代码
package com.macho.projects.lightcontroller;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import java.io.OutputStream;
import java.io.InputStream;
import java.io.*;
import android.bluetooth.*;
import java.util.*;
import android.os.*;
import android.util.*;
public class Physical extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_physical);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.menu_physical, menu);
return true;
}
private OutputStream outputStream;
private InputStream inStream;
public void Link (View v) throws IOException {
init();
v.bringToFront();
}
public void ON (View v) throws IOException
{
write("I");
}
public void OFF (View v) throws IOException
{
write("O");
}
private void init() throws IOException {
BluetoothAdapter blueAdapter = BluetoothAdapter.getDefaultAdapter();
if (blueAdapter != null) {
if (blueAdapter.isEnabled()) {
Set<BluetoothDevice> bondedDevices = blueAdapter.getBondedDevices();
if(bondedDevices.size() > 0){
BluetoothDevice[] devices = (BluetoothDevice[]) bondedDevices.toArray();
BluetoothDevice device = devices[0];
ParcelUuid[] uuidas = device.getUuids();
BluetoothSocket socket = device.createRfcommSocketToServiceRecord(uuidas[0].getUuid());
socket.connect();
outputStream = socket.getOutputStream();
inStream = socket.getInputStream();
}
Log.e("error", "No appropriate paired devices.");
}else{
Log.e("error", "Bluetooth is disabled.");
}
}
}
public void write(String s) throws IOException {
outputStream.write(s.getBytes());
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
//noinspection SimplifiableIfStatement
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
如果你们可以帮我一些代码，真的非常感谢。 对不起，如果我的英语不好。我不是母语。
日志：
09-13 09:27:46.652 23310-23310/com.macho.projects.lightcontroller D/OpenGLRenderer﹕ Enabling debug mode 0
09-13 09:28:19.179 23310-23310/com.macho.projects.lightcontroller D/AndroidRuntime﹕ Shutting down VM
09-13 09:28:19.179 23310-23310/com.macho.projects.lightcontroller W/dalvikvm﹕ threadid=1: thread exiting with uncaught exception (group=0x415d9d40)
09-13 09:28:19.197 23310-23310/com.macho.projects.lightcontroller E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.macho.projects.lightcontroller, PID: 23310
java.lang.IllegalStateException: Could not execute method of the activity
at android.view.View$1.onClick(View.java:3841)
at android.view.View.performClick(View.java:4456)
at android.view.View$PerformClick.run(View.java:18465)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.reflect.InvocationTargetException
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3836)
at android.view.View.performClick(View.java:4456)
at android.view.View$PerformClick.run(View.java:18465)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)
Caused by: java.lang.NullPointerException
at com.macho.projects.lightcontroller.Physical.write(Physical.java:75)
at com.macho.projects.lightcontroller.Physical.ON(Physical.java:44)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at android.view.View$1.onClick(View.java:3836)
at android.view.View.performClick(View.java:4456)
at android.view.View$PerformClick.run(View.java:18465)
at android.os.Handler.handleCallback(Handler.java:733)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:136)
at android.app.ActivityThread.main(ActivityThread.java:5086)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:785)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:601)
at dalvik.system.NativeStart.main(Native Method)