package com.scott.crash; 
 
import android.app.Activity; 
import android.os.Bundle; 
 
public class MainActivity extends Activity { 
 
  private String s; 
   
  @Override 
  public void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    System.out.println(s.equals("any string")); 
  } 
} 

package com.scott.crash; 
 
import java.io.File; 
import java.io.FileOutputStream; 
import java.io.PrintWriter; 
import java.io.StringWriter; 
import java.io.Writer; 
import java.lang.Thread.UncaughtExceptionHandler; 
import java.lang.reflect.Field; 
import java.text.DateFormat; 
import java.text.SimpleDateFormat; 
import java.util.Date; 
import java.util.HashMap; 
import java.util.Map; 
 
import android.content.Context; 
import android.content.pm.PackageInfo; 
import android.content.pm.PackageManager; 
import android.content.pm.PackageManager.NameNotFoundException; 
import android.os.Build; 
import android.os.Environment; 
import android.os.Looper; 
import android.util.Log; 
import android.widget.Toast; 
 
/** 
 * UncaughtException处理类,当程序发生Uncaught异常的时候,有该类来接管程序,并记录发送错误报告. 
 * 
 * @author user 
 * 
 */ 
public class CrashHandler implements UncaughtExceptionHandler { 
   
  public static final String TAG = "CrashHandler"; 
   
  //系统默认的UncaughtException处理类  
  private Thread.UncaughtExceptionHandler mDefaultHandler; 
  //CrashHandler实例 
  private static CrashHandler INSTANCE = new CrashHandler(); 
  //程序的Context对象 
  private Context mContext; 
  //用来存储设备信息和异常信息 
  private Map<String, String> infos = new HashMap<String, String>(); 
 
  //用于格式化日期,作为日志文件名的一部分 
  private DateFormat formatter = new SimpleDateFormat("yyyy-MM-dd-HH-mm-ss"); 
 
  /** 保证只有一个CrashHandler实例 */ 
  private CrashHandler() { 
  } 
 
  /** 获取CrashHandler实例 ,单例模式 */ 
  public static CrashHandler getInstance() { 
    return INSTANCE; 
  } 
 
  /** 
   * 初始化 
   * 
   * @param context 
   */ 
  public void init(Context context) { 
    mContext = context; 
    //获取系统默认的UncaughtException处理器 
    mDefaultHandler = Thread.getDefaultUncaughtExceptionHandler(); 
    //设置该CrashHandler为程序的默认处理器 
    Thread.setDefaultUncaughtExceptionHandler(this); 
  } 
 
  /** 
   * 当UncaughtException发生时会转入该函数来处理 
   */ 
  @Override 
  public void uncaughtException(Thread thread, Throwable ex) { 
    if (!handleException(ex) && mDefaultHandler != null) { 
      //如果用户没有处理则让系统默认的异常处理器来处理 
      mDefaultHandler.uncaughtException(thread, ex); 
    } else { 
      try { 
        Thread.sleep(3000); 
      } catch (InterruptedException e) { 
        Log.e(TAG, "error : ", e); 
      } 
      //退出程序 
      android.os.Process.killProcess(android.os.Process.myPid()); 
      System.exit(1); 
    } 
  } 
 
  /** 
   * 自定义错误处理,收集错误信息 发送错误报告等操作均在此完成. 
   * 
   * @param ex 
   * @return true:如果处理了该异常信息;否则返回false. 
   */ 
  private boolean handleException(Throwable ex) { 
    if (ex == null) { 
      return false; 
    } 
    //使用Toast来显示异常信息 
    new Thread() { 
      @Override 
      public void run() { 
        Looper.prepare(); 
        Toast.makeText(mContext, "很抱歉,程序出现异常,即将退出.", Toast.LENGTH_LONG).show(); 
        Looper.loop(); 
      } 
    }.start(); 
    //收集设备参数信息  
    collectDeviceInfo(mContext); 
    //保存日志文件  
    saveCrashInfo2File(ex); 
    return true; 
  } 
   
  /** 
   * 收集设备参数信息 
   * @param ctx 
   */ 
  public void collectDeviceInfo(Context ctx) { 
    try { 
      PackageManager pm = ctx.getPackageManager(); 
      PackageInfo pi = pm.getPackageInfo(ctx.getPackageName(), PackageManager.GET_ACTIVITIES); 
      if (pi != null) { 
        String versionName = pi.versionName == null ? "null" : pi.versionName; 
        String versionCode = pi.versionCode + ""; 
        infos.put("versionName", versionName); 
        infos.put("versionCode", versionCode); 
      } 
    } catch (NameNotFoundException e) { 
      Log.e(TAG, "an error occured when collect package info", e); 
    } 
    Field[] fields = Build.class.getDeclaredFields(); 
    for (Field field : fields) { 
      try { 
        field.setAccessible(true); 
        infos.put(field.getName(), field.get(null).toString()); 
        Log.d(TAG, field.getName() + " : " + field.get(null)); 
      } catch (Exception e) { 
        Log.e(TAG, "an error occured when collect crash info", e); 
      } 
    } 
  } 
 
  /** 
   * 保存错误信息到文件中 
   * 
   * @param ex 
   * @return 返回文件名称,便于将文件传送到服务器 
   */ 
  private String saveCrashInfo2File(Throwable ex) { 
     
    StringBuffer sb = new StringBuffer(); 
    for (Map.Entry<String, String> entry : infos.entrySet()) { 
      String key = entry.getKey(); 
      String value = entry.getValue(); 
      sb.append(key + "=" + value + "\n"); 
    } 
     
    Writer writer = new StringWriter(); 
    PrintWriter printWriter = new PrintWriter(writer); 
    ex.printStackTrace(printWriter); 
    Throwable cause = ex.getCause(); 
    while (cause != null) { 
      cause.printStackTrace(printWriter); 
      cause = cause.getCause(); 
    } 
    printWriter.close(); 
    String result = writer.toString(); 
    sb.append(result); 
    try { 
      long timestamp = System.currentTimeMillis(); 
      String time = formatter.format(new Date()); 
      String fileName = "crash-" + time + "-" + timestamp + ".log"; 
      if (Environment.getExternalStorageState().equals(Environment.MEDIA_MOUNTED)) { 
        String path = "/sdcard/crash/"; 
        File dir = new File(path); 
        if (!dir.exists()) { 
          dir.mkdirs(); 
        } 
        FileOutputStream fos = new FileOutputStream(path + fileName); 
        fos.write(sb.toString().getBytes()); 
        fos.close(); 
      } 
      return fileName; 
    } catch (Exception e) { 
      Log.e(TAG, "an error occured while writing file...", e); 
    } 
    return null; 
  } 
} 

package com.scott.crash; 
 
import android.app.Application; 
 
public class CrashApplication extends Application { 
  @Override 
  public void onCreate() { 
    super.onCreate(); 
    CrashHandler crashHandler = CrashHandler.getInstance(); 
    crashHandler.init(getApplicationContext()); 
  } 
} 

<application android:name=".CrashApplication" ...> 
</application> 

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> 

CPU_ABI=armeabi 
CPU_ABI2=unknown 
ID=FRF91 
MANUFACTURER=unknown 
BRAND=generic 
TYPE=eng 
...... 
Caused by: java.lang.NullPointerException 
  at com.scott.crash.MainActivity.onCreate(MainActivity.java:13) 
  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047) 
  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2627) 
  ... 11 more 

/**
 * 网络是否可用
*/  
 public static boolean isNetworkAvailable(Context context) { 
    ConnectivityManager mgr = (ConnectivityManager) context.getSystemService(Context.CONNECTIVITY_SERVICE); 
    NetworkInfo[] info = mgr.getAllNetworkInfo(); 
    if (info != null) { 
      for (int i = 0; i < info.length; i++) { 
        if (info[i].getState() == NetworkInfo.State.CONNECTED) { 
          return true; 
        } 
      } 
    } 
    return false; 
  }