应用程序关闭没有任何理由？

-3

我是ameture的android应用程序制造商，下面是我的第一个应用程序。该应用程序的基本功能是获取手机位置，延迟5秒钟，并运行另一个getLocation;那么它会根据两点计算出速度，并指出用户是否在使用手机时行走。应用程序关闭没有任何理由？

Studio中的代码没问题，但是当我尝试运行我的应用程序时，手机只是说'应用程序已停止'。它关闭了应用程序。我花了几个小时试图弄清楚，但无济于事。

我在做什么错？

package com.example.denny.myapplication; 

import android.Manifest.permission; 
import android.app.AlertDialog; 
import android.content.Context; 
import android.content.DialogInterface; 
import android.content.Intent; 
import android.content.pm.PackageManager; 
import android.location.Location; 
import android.location.LocationManager; 
import android.os.Build; 
import android.os.Bundle; 
import android.os.Handler; 
import android.provider.Settings; 
import android.support.design.widget.FloatingActionButton; 
import android.support.design.widget.Snackbar; 
import android.support.v7.app.AppCompatActivity; 
import android.support.v7.widget.Toolbar; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 

public class MainActivity extends AppCompatActivity { 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     PackageManager pm = getPackageManager(); 
     if (pm.checkPermission(permission.ACCESS_FINE_LOCATION, getPackageName()) == PackageManager.PERMISSION_DENIED) { 
      alertboxGPS(); 
     } 
     mHandler = new Handler(); 
     startRepeatingTask(); 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar); 
     setSupportActionBar(toolbar); 
     FloatingActionButton fab = (FloatingActionButton) findViewById(R.id.fab); 
     fab.setOnClickListener(new View.OnClickListener() { 
            @Override 
            public void onClick(View view) { 
             Snackbar.make(view, "Replace with your own action", Snackbar.LENGTH_LONG) 
               .setAction("Action", null).show(); 

            } 
           } 
     ); 
    } 


    @Override 
    public boolean onCreateOptionsMenu(Menu menu) { 
     getMenuInflater().inflate(R.menu.menu_main, menu); 
     return true; 
    } 

    @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. 

     //Also, chuck the subroutine settings here. :3 
     int id = item.getItemId(); 

     //noinspection SimplifiableIfStatement 
     if (id == R.id.action_settings) { 
      return true; 
     } 

     return super.onOptionsItemSelected(item); 
    } 

    PackageManager pm = getPackageManager(); 

    protected void alertboxGPS() { 
     AlertDialog.Builder builder = new AlertDialog.Builder(this); 
     builder.setMessage("Your Device's GPS is Disabled") 
       .setCancelable(true) 
       .setTitle("** Gps Status **") 
       .setPositiveButton("Gps On", 
         new DialogInterface.OnClickListener() { 
          public void onClick(DialogInterface dialog, int id) { 
           // finish the current activity 
           // AlertBoxAdvance.this.finish(); 
           Intent myIntent = new Intent(
             Settings.ACTION_SECURITY_SETTINGS); 
           startActivity(myIntent); 
           dialog.cancel(); 
          } 
         }) 
       .setNegativeButton("Cancel", 
         new DialogInterface.OnClickListener() { 
          public void onClick(DialogInterface dialog, int id) { 
           // cancel the dialog box 
           dialog.cancel(); 
          } 
         }); 
     AlertDialog alert = builder.create(); 
     alert.show(); 
    } 

    protected void alertboxViolation() { 
     AlertDialog.Builder builder = new AlertDialog.Builder(this); 
     builder.setMessage("Please stop walking. You may get in an accident.") 
       .setCancelable(false) 
       .setTitle("Walking Warning") 
       .setPositiveButton("Stop Walking", 
         new DialogInterface.OnClickListener() { 
          public void onClick(DialogInterface dialog, int id) { 
           // finish the current activity 
           // AlertBoxAdvance.this.finish(); 
           Intent myIntent = new Intent(
             Settings.ACTION_SECURITY_SETTINGS); 
           startActivity(myIntent); 
           dialog.cancel(); 
          } 
         }) 
       .setNegativeButton("Cancel", 
         new DialogInterface.OnClickListener() { 
          public void onClick(DialogInterface dialog, int id) { 
           // cancel the dialog box 
           dialog.cancel(); 
          } 
         }); 
     AlertDialog alert = builder.create(); 
     alert.show(); 
    } 

    //Some Default Integers 
    int ViolationLimit = 10; 
    int SpeedLimit = 100; 
    int ExceedInstance = 0; 

    //Default Value 
    LocationManager lm = (LocationManager) getSystemService(Context.LOCATION_SERVICE); 
    Location location1; 
    Location location2; 

    private double GetSpeed(Location location1, Location location2) { 

     if (location1 == null) { 

      location1 = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER); 
      location2 = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER); 
     } else { 
      location1 = location2; 
      if (checkSelfPermission(permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && checkSelfPermission(permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) { 

      } 
      location2 = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER); 

     } 
     double Distance; 
     Distance = location1.distanceTo(location2); 
     double Speed = Distance/mInterval; 
     return Speed; 
    } 


    private int Judge(double Speed, int ViolationLimit, int SpeedLimit, int ExceedInstance) { 
     if (Speed >= 1 && Speed <= SpeedLimit) { 
      ExceedInstance += 1; 
     } 

     if (ExceedInstance >= ViolationLimit) { 
      alertboxViolation(); 
     } 
     return ExceedInstance; 
    } 

    void stopRepeatingTask() { 
     mHandler.removeCallbacks(mStatusChecker); 
    } 

    private int mInterval = 3000; // 3 seconds by default, can be changed later 
    private Handler mHandler; 
    Runnable mStatusChecker = new Runnable() { 
     @Override 
     public void run() { 
      updateStatus(); 
      mHandler.postDelayed(mStatusChecker, mInterval); 
     } 
    }; 

    private void updateStatus() { 
     //Is used for updating mInterval 
    } 

    void startRepeatingTask() { 
     double Speed = GetSpeed(location1, location2); 
     Judge(Speed, ViolationLimit, SpeedLimit, ExceedInstance); 
     mStatusChecker.run(); 
    } 
}

logcat的日志：

10-13 23:23:55.818 13410-13410/? E/SELinux: Function: selinux_android_load_priority [0], There is no sepolicy file 
10-13 23:23:55.818 13410-13410/? E/SELinux: 
10-13 23:23:55.818 13410-13410/? E/SELinux: Function: selinux_android_load_priority , loading version is VE=SEPF_GT-I9505_4.3_0024 
10-13 23:23:55.818 13410-13410/? E/SELinux: 
10-13 23:23:55.818 13410-13410/? E/SELinux: 
10-13 23:23:55.818 13410-13410/? E/SELinux: selinux_android_seapp_context_reload: seapp_contexts file is loaded from /data/security/spota/seapp_contexts 
10-13 23:23:55.818 13410-13410/? D/dalvikvm: Late-enabling CheckJNI 
10-13 23:23:55.928 13410-13410/com.example.denny.myapplication I/dalvikvm: Could not find method com.example.denny.myapplication.MainActivity.checkSelfPermission, referenced from method com.example.denny.myapplication.MainActivity.GetSpeed 
10-13 23:23:55.928 13410-13410/com.example.denny.myapplication W/dalvikvm: VFY: unable to resolve virtual method 16261: Lcom/example/denny/myapplication/MainActivity;.checkSelfPermission (Ljava/lang/String;)I 
10-13 23:23:55.928 13410-13410/com.example.denny.myapplication D/dalvikvm: VFY: replacing opcode 0x6e at 0x0028 
10-13 23:23:55.938 13410-13410/com.example.denny.myapplication D/AndroidRuntime: Shutting down VM 
10-13 23:23:55.938 13410-13410/com.example.denny.myapplication W/dalvikvm: threadid=1: thread exiting with uncaught exception (group=0x4190e898) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime: FATAL EXCEPTION: main 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime: java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{com.example.denny.myapplication/com.example.denny.myapplication.MainActivity}: java.lang.NullPointerException 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2219) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.ActivityThread.access$700(ActivityThread.java:159) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.os.Handler.dispatchMessage(Handler.java:99) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.os.Looper.loop(Looper.java:137) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.ActivityThread.main(ActivityThread.java:5419) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at java.lang.reflect.Method.invokeNative(Native Method) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at java.lang.reflect.Method.invoke(Method.java:525) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1187) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at dalvik.system.NativeStart.main(Native Method) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime: Caused by: java.lang.NullPointerException 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.content.ContextWrapper.getPackageManager(ContextWrapper.java:94) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at com.example.denny.myapplication.MainActivity.<init>(MainActivity.java:74) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at java.lang.Class.newInstanceImpl(Native Method) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at java.lang.Class.newInstance(Class.java:1130) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.Instrumentation.newActivity(Instrumentation.java:1078) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2210) 
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2349)  
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.ActivityThread.access$700(ActivityThread.java:159)  
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1316)  
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.os.Handler.dispatchMessage(Handler.java:99)  
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.os.Looper.loop(Looper.java:137)  
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at android.app.ActivityThread.main(ActivityThread.java:5419)  
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at java.lang.reflect.Method.invokeNative(Native Method)  
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at java.lang.reflect.Method.invoke(Method.java:525)  
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1187)  
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)  
10-13 23:23:55.948 13410-13410/com.example.denny.myapplication E/AndroidRuntime:  at dalvik.system.NativeStart.main(Native Method)  
10-13 23:24:03.355 13410-13410/com.example.denny.myapplication I/Process: Sending signal. PID: 13410 SIG: 9

这是一个相当大的日志，但我不知道该怎么做，在一个更好的方式。

免责声明 这个问题是不一样的NULL指针的问题，因为我已经做了一个应用程序，我不知道是什么原因造成的。这就是为什么我问这个问题。

来源

2015-10-13 Mildwood

你能提供一些日志吗？ – ThomasThiebaud

当然...编辑包括lolcat（我的意思是logcat）消息。 – Mildwood

[什么是空指针异常，以及如何解决它？]可能重复（http://stackoverflow.com/questions/218384/what-is-a-null-pointer-exception-and-how-do -i-fix-it） – Selvin

首先，关于您的评论文字：

这个问题是问的东西有人不知道。我的应用程序是，我不知道它为什么会关闭。请不要假设每个人都知道他们在做什么，当他们提问时所做的一切。

人们正试图帮助你。在写这样的评论之前，你可能想重新考虑你的态度。

其次，@Selvin是正确的。你logcat的输出中明确指出，您的应用程序崩溃是由一个NullPointerException（NPE）引起的：

E/AndroidRuntime: Caused by: java.lang.NullPointerException

NullPointerException异常的是通过在代码（amoungst其他东西）坏逻辑造成的。您的代码是应用程序的一部分的事实是无关紧要的。您应该阅读linked question以了解NPE是什么以及它们发生的原因。

讲座，让我们看看你的问题。

Logcat为您提供了大量有关错误的信息，通常包括显示问题的原因和堆栈跟踪。所以，从顶部：

E/AndroidRuntime: FATAL EXCEPTION: main 
java.lang.RuntimeException: Unable to instantiate activity ComponentInfo{...}: java.lang.NullPointerException

OK，这是你的Activity的实例化过程中一个NullPointerException。为什么？

Caused by: java.lang.NullPointerException 
E/AndroidRuntime:  at android.content.ContextWrapper.getPackageManager(ContextWrapper.java:94) 
at com.example.denny.myapplication.MainActivity.<init>(MainActivity.java:74)

所以有一个问题，调用getPackageManager()。 您最近的位置代码是MainActivity.<init>, MainActivity.java, line 74

<init>只是“在构建对象期间”的Java方法。

看你的源代码，您正试图对象的构造过程中初始化一个PackageManager pm字段实例：

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
... 
} 

PackageManager pm = getPackageManager(); 

protected void alertboxGPS() { 
... 
}

的问题是，getPackageManager()被调用，而你的Activity实例是正在兴建的中间 - 并非所有事情都会在这个时候做好准备。

对getPackageManager()的调用尝试使用尚未创建的对象（因此为NullPointerException）几乎肯定是这种情况。

一种解决方法是删除初始化你pm领域，而是，在onCreate()设置 - 在这一点上，你Activity实例将被完全构造和getPackageManager()呼叫将会成功。

更好的解决方案是完全删除pm字段，只需在需要时创建局部变量 - 就像您在onCreate()中已经在做的那样。

来源

2015-10-13 17:55:04 adelphus

对不起我的粗鲁，有时我会变得烦躁不安。我已经解决了我的问题，并继续解决我的问题。 – Mildwood

应用程序关闭没有任何理由？

回答

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