接收广播意图ACTION_POWER_DISCONNECTED时出错

Question

我是一个新的android .I我得到一个运行时异常说“错误接收广播意图ACTION_POWER_DISCONNECTED ".I在我的活动的onCreate()中实例化我的接收器，然后我在onResume()中注册我的接收器，并在onPause()方法中取消注册它。实际上我想根据我的应用的收费模式来设置文本收费和不收费

package com.example.mrfrag.firebattery;

import android.content.BroadcastReceiver;
import android.content.ContentProvider;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class HomeActivity extends AppCompatActivity{

TextView batteryplus,temp,setting,plug,charging,battery;
private BroadcastReceiver mReceiver;
IntentFilter ifilter =new IntentFilter();

@Override
protected void onCreate(Bundle savedInstanceState) {

    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_home);
    batteryplus=  findViewById(R.id.batteryplus);
    temp =  findViewById(R.id.temp);
    setting=  findViewById(R.id.setting);
    plug=  findViewById(R.id.plug);
    charging=  findViewById(R.id.charging);
    battery=  findViewById(R.id.battery);
    mReceiver=new PowerConnectionReceiver();
    ifilter.addAction(Intent.ACTION_POWER_CONNECTED);
    ifilter.addAction(Intent.ACTION_POWER_DISCONNECTED);
    ifilter.addAction(Intent.ACTION_BATTERY_CHANGED);

}

@Override
protected void onResume() {
    super.onResume();
    registerReceiver(mReceiver, ifilter);
}

@Override
protected void onPause() {
    super.onPause();
    unregisterReceiver(mReceiver);
}

public class PowerConnectionReceiver extends BroadcastReceiver {
    public PowerConnectionReceiver(){

    }
    @Override
    public void onReceive(Context context, Intent batteryStatus) {
        int status = batteryStatus.getIntExtra(BatteryManager.EXTRA_STATUS, 
-1);

        boolean isCharging = status == BatteryManager.BATTERY_STATUS_CHARGING 
 ||
                status == BatteryManager.BATTERY_STATUS_FULL;
        if (isCharging) {

            plug.setText("CHARGING");
        } else {

            plug.setText("NOT CHARGING");

        }
        int  health = 
    batteryStatus.getIntExtra(BatteryManager.EXTRA_HEALTH,0);
        batteryplus.setText(ConvoHealth(health));
        String  technology = 
    batteryStatus.getExtras().getString(BatteryManager.EXTRA_TECHNOLOGY);
        setting.setText(technology);
        float  tpr   = ((float) 
 batteryStatus.getIntExtra(BatteryManager.EXTRA_TEMPERATURE,0)) / 10.0f;
        temp.setText( String.valueOf(tpr) + "°C / " + 
 String.valueOf(tpr*1.8+32)+"F"+"\n");
        int  voltage = 
  batteryStatus.getIntExtra(BatteryManager.EXTRA_VOLTAGE,0);
        charging.setText(voltage+ " mV");
        int  mah = batteryStatus.getIntExtra(String.valueOf
   (BatteryManager.BATTERY_PROPERTY_CAPACITY),0);
        battery.setText(mah+ " Mah");

    }
}

private String ConvoHealth(int health){
    String result;
    switch(health){
        case BatteryManager.BATTERY_HEALTH_COLD:
            result = "COLD";
            break;
        case BatteryManager.BATTERY_HEALTH_DEAD:
            result = "DEAD";
            break;
        case BatteryManager.BATTERY_HEALTH_GOOD:
            result = "GOOD";
            break;
        case BatteryManager.BATTERY_HEALTH_OVERHEAT:
            result = "OVERHEAT";
            break;
        case BatteryManager.BATTERY_HEALTH_OVER_VOLTAGE:
            result = "OVER VOLTAGE";
            break;
        case BatteryManager.BATTERY_HEALTH_UNKNOWN:
            result = "UNKNOWN";
            break;
        case BatteryManager.BATTERY_HEALTH_UNSPECIFIED_FAILURE:
            result = "UNSPECIFIED_FAILURE";
            break;
        default:
            result = "Unknown";
    }
     return result;
 }

}

This is my AndroidManifest.xml file

This is Runtime exception

Answer 1

出现此异常的原因是因为下面这行代码：

String  technology = 
    batteryStatus.getExtras().getString(BatteryManager.EXTRA_TECHNOLOGY);
        setting.setText(technology);

上面这行抛出了空指针。此额外功能仅适用于Intent.ACTION_BATTERY_CHANGED。因此要么将其删除，要么添加条件

if(intent.getAction().equals(Intent.ACTION_BATTERY_CHANGED)){
    String  technology = 
    batteryStatus.getExtras().getString(BatteryManager.EXTRA_TECHNOLOGY);
        setting.setText(technology);
     setting.setText(technology);
}