使用设备时应用中的Android实例化异常admin

的logcat：

07-29 19:15:05.509: D/libEGL(31021): loaded /system/lib/egl/libEGL_mali.so 
07-29 19:15:05.544: D/libEGL(31021): loaded /system/lib/egl/libGLESv1_CM_mali.so 
07-29 19:15:05.549: D/libEGL(31021): loaded /system/lib/egl/libGLESv2_mali.so 
07-29 19:15:05.549: D/(31021): Device driver API match 
07-29 19:15:05.549: D/(31021): Device driver API version: 10 
07-29 19:15:05.549: D/(31021): User space API version: 10 
07-29 19:15:05.549: D/(31021): mali: REVISION=Linux-r2p4-02rel0 BUILD_DATE=Mon Mar 5 09:47:55 KST 2012 
07-29 19:15:05.574: D/OpenGLRenderer(31021): Enabling debug mode 0 
07-29 19:15:07.509: W/IInputConnectionWrapper(31021): showStatusIcon on inactive InputConnection 
07-29 19:15:08.444: D/dalvikvm(31021): newInstance failed: no <init>() 
07-29 19:15:08.444: D/AndroidRuntime(31021): Shutting down VM 
07-29 19:15:08.444: W/dalvikvm(31021): threadid=1: thread exiting with uncaught exception (group=0x41443300) 
07-29 19:15:08.549: E/AndroidRuntime(31021): FATAL EXCEPTION: main 
07-29 19:15:08.549: E/AndroidRuntime(31021): java.lang.RuntimeException: Unable to instantiate receiver com.liamwli.parent.trap.ParentTrap$Controller: java.lang.InstantiationException: can't instantiate class com.liamwli.parent.trap.ParentTrap$Controller; no empty constructor 
07-29 19:15:08.549: E/AndroidRuntime(31021): at android.app.ActivityThread.handleReceiver(ActivityThread.java:2333) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at android.app.ActivityThread.access$1500(ActivityThread.java:139) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1281) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at android.os.Handler.dispatchMessage(Handler.java:99) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at android.os.Looper.loop(Looper.java:137) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at android.app.ActivityThread.main(ActivityThread.java:4896) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at java.lang.reflect.Method.invokeNative(Native Method) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at java.lang.reflect.Method.invoke(Method.java:511) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:788) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:555) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at dalvik.system.NativeStart.main(Native Method) 
07-29 19:15:08.549: E/AndroidRuntime(31021): Caused by: java.lang.InstantiationException: can't instantiate class com.liamwli.parent.trap.ParentTrap$Controller; no empty constructor 
07-29 19:15:08.549: E/AndroidRuntime(31021): at java.lang.Class.newInstanceImpl(Native Method) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at java.lang.Class.newInstance(Class.java:1319) 
07-29 19:15:08.549: E/AndroidRuntime(31021): at android.app.ActivityThread.handleReceiver(ActivityThread.java:2328) 
07-29 19:15:08.549: E/AndroidRuntime(31021): ... 10 more 
07-29 19:15:09.719: I/Process(31021): Sending signal. PID: 31021 SIG: 9

Acitvity：

package com.liamwli.parent.trap; 

import android.os.Bundle; 
import android.app.Activity; 
import android.app.admin.DeviceAdminReceiver; 
import android.app.admin.DevicePolicyManager; 
import android.content.ComponentName; 
import android.content.Context; 
import android.content.Intent; 
import android.view.Menu; 
import android.view.MenuItem; 
import android.view.View; 
import android.widget.Button; 
import android.widget.EditText; 
import android.widget.Toast; 
import android.support.v4.app.NavUtils; 



public class ParentTrap extends Activity { 

    Button dae, dad, spass; 
    EditText pass; 
    ComponentName mDeviceAdminSample; 
    static final int RESULT_ENABLE = 1; 

    @Override 
    public void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.main); 

     dae = (Button) findViewById(R.id.benablea); 
     dae.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View arg0) { 
       // TODO Auto-generated method stub 

       mDeviceAdminSample = new ComponentName(ParentTrap.this, 
         Controller.class); 

       Intent intent = new Intent(
         DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN); 
       intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, 
         mDeviceAdminSample); 
       intent.putExtra(DevicePolicyManager.EXTRA_ADD_EXPLANATION, 
         "Title"); 
       startActivityForResult(intent, RESULT_ENABLE); 

      } 
     }); 
     dad = (Button) findViewById(R.id.button1); 
     dad.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View arg0) { 
       // TODO Auto-generated method stub 

      } 
     }); 
     spass = (Button) findViewById(R.id.button2); 
     spass.setOnClickListener(new View.OnClickListener() { 

      @Override 
      public void onClick(View arg0) { 
       // TODO Auto-generated method stub 

      } 
     }); 

     pass = (EditText) findViewById(R.id.editText1); 

     dad.setEnabled(false); 
    } 

    public class Controller extends DeviceAdminReceiver { 

     void showToast(Context context, String msg) { 
      String status = "Status"; 
      Toast.makeText(context, status, Toast.LENGTH_SHORT).show(); 
     } 

     @Override 
     public void onEnabled(Context context, Intent intent) { 
      showToast(context, "Enabled"); 
     } 

     @Override 
     public CharSequence onDisableRequested(Context context, Intent intent) { 
      return "Disable Requested"; 
     } 

     @Override 
     public void onDisabled(Context context, Intent intent) { 
      showToast(context, "Disabled"); 
     } 

     @Override 
     public void onPasswordChanged(Context context, Intent intent) { 
      showToast(context, "Device PIN Changed"); 
     } 

    } 

} 

class evilliam { 

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

请帮我这个问题，我保证不打扰你，直到明天:)

来源

2012-07-29 Liam W

你有没有做过任何调试？你认为这个错误在哪里？ – Keppil 2012-07-29 18:29:34

我不明白这个错误。我知道我没有空的构造函数 - 但我该如何创建一个，我在哪里放置它？ – 2012-07-29 18:41:37

http://docs.oracle.com/javase/tutorial/java/javaOO/constructors.html – Keppil 2012-07-29 18:45:57

Caused by: java.lang.InstantiationException: can't instantiate class com.liamwli.parent.trap.ParentTrap$Controller; no empty constructor

这表明，控制器需要一个默认构造函数，如下所示：

public class Controller extends DeviceAdminReceiver { 
    public Controller() { 
     super(); 
    } 

    void showToast(Context context, String msg) { 
     String status = "Status"; 
     Toast.makeText(context, status, Toast.LENGTH_SHORT).show(); 

     //Toast.makeText(context, msg, Toast.LENGTH_SHORT).show(); 
    } 
    ... 
}

来源

2012-07-29 18:45:52 Sam

使用设备时应用中的Android实例化异常admin

回答

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