Android異常嘗試調用虛擬方法'int android.content.Context.checkPermission（java.lang.String，int，int）

Question

我正在編程一個應用程序來刪除通話記錄。這裏是代碼

public class PhoneStateReceiver extends BroadcastReceiver { 
@Override 
public void onReceive(Context context, Intent intent) { 

    try { 
     System.out.println("Receiver start"); 
     String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE); 
     String incomingNumber = intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER); 


     if (state.equals(TelephonyManager.EXTRA_STATE_IDLE)) { 
      Toast.makeText(context, "Call Idle State"+incomingNumber, Toast.LENGTH_SHORT).show(); 


       DeleteCallLogByNumber("97********"); 
       Toast.makeText(context, "Log deleted", Toast.LENGTH_SHORT).show(); 


     } 
    } catch (Exception e) { 
     e.printStackTrace(); 
    } 

} 

public void DeleteCallLogByNumber(String number) { 
    String queryString = "NUMBER=" + number; 


    if (ActivityCompat.checkSelfPermission(MainActivity.Context(), Manifest.permission.WRITE_CALL_LOG) != PackageManager.PERMISSION_GRANTED) { 

     return; 
    } 
    MainActivity.ContentResolver().delete(CallLog.Calls.CONTENT_URI, queryString, null); 
    } 
} 

我得到異常作爲

顯示java.lang.NullPointerException：試圖調用虛擬方法INT android.content.Context.checkPermission（java.lang.String中，INT，INT ）」對空對象引用

Answer 1

我想通了自己

public class PhoneStateReceiver extends BroadcastReceiver { 
@Override 
public void onReceive(Context context, Intent intent) { 

try { 
    System.out.println("Receiver start"); 
    String state = intent.getStringExtra(TelephonyManager.EXTRA_STATE); 
    String incomingNumber = intent.getStringExtra(TelephonyManager.EXTRA_INCOMING_NUMBER); 


    if (state.equals(TelephonyManager.EXTRA_STATE_IDLE)) { 
     Toast.makeText(context, "Call Idle State"+incomingNumber, Toast.LENGTH_SHORT).show(); 


      DeleteCallLogByNumber("97********", context); 
      Toast.makeText(context, "Log deleted", Toast.LENGTH_SHORT).show(); 


    } 
} catch (Exception e) { 
    e.printStackTrace(); 
    } 

} 

public void DeleteCallLogByNumber(String number, Context context) { 
String queryString = "NUMBER='" + number+"'"; 


if (ActivityCompat.checkSelfPermission(context, Manifest.permission.WRITE_CALL_LOG) != PackageManager.PERMISSION_GRANTED) { 

    return; 
} 
context.getContentResolver().delete(CallLog.Calls.CONTENT_URI, queryString, null); 
} 
}