出于某种原因，这个新的蓝牙代码导致我的应用程序“停止工作”并崩溃。当我得到这样的错误时，我怀疑它是Android Manifest。但是，我发现它没有任何问题。请将注意力集中在启动功能中的蓝牙代码上。没有它的代码工作而不会崩溃应用程序。我的格式也非常苛刻。
主要Activity.java
package com.example.real;
import java.util.Set;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.Context;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.net.Uri;
import android.os.Bundle;
import android.os.CountDownTimer;
import android.speech.tts.TextToSpeech;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class MainActivity extends Activity implements LocationListener{
Button start, stop;
TextView tv;
TextView tv2;
TextView sum;
LocationManager lm;
TextToSpeech Talker;
Intent phone = new Intent(Intent.ACTION_CALL);
String Hello = ("Hello World");
int i,sum1;
BluetoothAdapter mBluetoothAdapter;
BluetoothDevice mmDevice;
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Initilize Test Function Hello World
Button button = (Button) this.findViewById(R.id.Button01);
button.setOnClickListener(new OnClickListener()
{
@Override
public void onClick(View v)
{
Toast.makeText(MainActivity.this, "GPS in Progress", Toast.LENGTH_SHORT).show();
}
});
//Initialize Counter Sequence
start = (Button)findViewById(R.id.start);// Launch Seizure Sequence
stop = (Button)findViewById(R.id.stop);//Override Function
tv = (TextView)findViewById(R.id.tv);
tv.setText("30"); // starting from 30.
sum = (TextView)findViewById(R.id.sum);
final MyCounter timer = new MyCounter(30000,1000);
start.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v)
{
if(pairedDevices.size() > 0)
{
for(BluetoothDevice device : pairedDevices)
{
if(device.getName().equals("uIceblue2"))
{
mmDevice = device;
for(i=0;i<100;i++)
{
sum1 = sum1 + i;
sum.setText("Sum:"+sum1);
if(sum1 > 120)
{
timer.start();
}
}
}
}
}
}
});
stop.setOnClickListener(new OnClickListener() {
@Override
public void onClick(View v) {
timer.cancel();
tv.setText("Emergency Call to first responders prevented");
}
});
//Initialize GPS layout
tv2 = (TextView) findViewById(R.id.GPS);
lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
lm.requestLocationUpdates(LocationManager.GPS_PROVIDER, 20, 1, this);
}
public class MyCounter extends CountDownTimer{
public MyCounter(long millisInFuture, long countDownInterval) {
super(millisInFuture, countDownInterval);
}
@Override
public void onFinish() {
System.out.println("Timer Completed.");
tv.setText("Sending information to first responders.");
phone.setData(Uri.parse("tel:7034004407"));
startActivity(phone);
}
@Override
public void onTick(long millisUntilFinished) {
tv.setText((millisUntilFinished/1000)+"");
System.out.println("Timer : " + (millisUntilFinished/1000));
}
}
@Override
public void onLocationChanged(Location arg0)
{
String lat = String.valueOf(arg0.getLatitude());
String lon = String.valueOf(arg0.getLongitude());
Log.e("GPS", "location changed: lat="+lat+", lon="+lon);
tv2.setText("lat="+lat+", long="+lon);
}
public void onProviderDisabled(String arg0) {
Log.e("GPS", "provider disabled " + arg0);
}
public void onProviderEnabled(String arg0) {
Log.e("GPS", "provider enabled " + arg0);
}
public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
Log.e("GPS", "status changed to " + arg0 + " [" + arg1 + "]");
}
}
清单
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.real"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="@drawable/ic_launcher"
android:label="@string/app_name"
android:theme="@style/AppTheme" >
<activity
android:name="com.example.real.MainActivity"
android:label="@string/app_name"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
<uses-permission
android:name="android.permission.ACCESS_COARSE_LOCATION" />
<uses-permission
android:name="android.permission.ACCESS_FINE_LOCATION" />
<uses-permission
android:name="android.permission.ACCESS_LOCATION_EXTRA_COMMANDS" />
<uses-permission
android:name="android.permission.ACCESS_MOCK_LOCATION" />
<uses-permission
android:name="android.permission.BLUETOOTH" />
<uses-permission
android:name="android.permission.BLUETOOTH_ADMIN" />
<uses-permission
android:name="android.permission.CALL_PHONE" />
<uses-permission android:name="android.permission.INTERNET" />
</manifest>
错误记录
10-24 16:58:12.716: E/AndroidRuntime(794): FATAL EXCEPTION: main
10-24 16:58:12.716: E/AndroidRuntime(794): java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.real/com.example.real.MainActivity}: java.lang.NullPointerException
10-24 16:58:12.716: E/AndroidRuntime(794): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2137)
10-24 16:58:12.716: E/AndroidRuntime(794): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2261)
10-24 16:58:12.716: E/AndroidRuntime(794): at android.app.ActivityThread.access$600(ActivityThread.java:141)
10-24 16:58:12.716: E/AndroidRuntime(794): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1256)
10-24 16:58:12.716: E/AndroidRuntime(794): at android.os.Handler.dispatchMessage(Handler.java:99)
10-24 16:58:12.716: E/AndroidRuntime(794): at android.os.Looper.loop(Looper.java:137)
10-24 16:58:12.716: E/AndroidRuntime(794): at android.app.ActivityThread.main(ActivityThread.java:5103)
10-24 16:58:12.716: E/AndroidRuntime(794): at java.lang.reflect.Method.invokeNative(Native Method)
10-24 16:58:12.716: E/AndroidRuntime(794): at java.lang.reflect.Method.invoke(Method.java:525)
10-24 16:58:12.716: E/AndroidRuntime(794): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
10-24 16:58:12.716: E/AndroidRuntime(794): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
10-24 16:58:12.716: E/AndroidRuntime(794): at dalvik.system.NativeStart.main(Native Method)
10-24 16:58:12.716: E/AndroidRuntime(794): Caused by: java.lang.NullPointerException
10-24 16:58:12.716: E/AndroidRuntime(794): at com.example.real.MainActivity.<init>(MainActivity.java:124)
10-24 16:58:12.716: E/AndroidRuntime(794): at java.lang.Class.newInstanceImpl(Native Method)
10-24 16:58:12.716: E/AndroidRuntime(794): at java.lang.Class.newInstance(Class.java:1130)
10-24 16:58:12.716: E/AndroidRuntime(794): at android.app.Instrumentation.newActivity(Instrumentation.java:1061)
10-24 16:58:12.716: E/AndroidRuntime(794): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2128)
10-24 16:58:12.716: E/AndroidRuntime(794): ... 11 more
谢谢!!!
答案 0 :(得分：0)
您的问题是您尝试使用mBluetoothAdapter构建成员变量。
BluetoothAdapter mBluetoothAdapter; //mBluetoothAdapter is null.
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();