Question

我已经尝试了几个小时才能让它发挥作用。我试图将电池信息从活动传递到片段。我一直收到NullPointerException。

java.lang.NullPointerException: Attempt to invoke virtual method 'int  
android.os.Bundle.getInt(java.lang.String)' on a null object reference

我已经查看了互联网上的许多其他用户问题，但我还没有找到解决方案。我的片段代码：

package natanrosenfeld.systeminfo;

import android.annotation.TargetApi;
import android.os.BatteryManager;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.Toast;

/**
* Created by natanrosenfeld on 6/18/15.
*/
@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public class BatteryInfoFragment extends Fragment {

/*private String [] batteryProperties = {"Battery Plugged AC: " +   
BatteryManager.BATTERY_PLUGGED_AC,
        "Battery Plugged USB: " + BatteryManager.BATTERY_PLUGGED_USB,  
"Battery Plugged Wireless: " + BatteryManager.BATTERY_PLUGGED_WIRELESS,
"Battery Capacity: " + BatteryManager.BATTERY_PROPERTY_CAPACITY, "Battery   
Charge Counter: " + BatteryManager.BATTERY_PROPERTY_CHARGE_COUNTER,
"Battery Current Average: " +  
BatteryManager.BATTERY_PROPERTY_CURRENT_AVERAGE, "Battery Current Now: " + 
BatteryManager.BATTERY_PROPERTY_CURRENT_NOW,
"Battery Energy Counter: " + BatteryManager.BATTERY_PROPERTY_ENERGY_COUNTER, 
"Battery Status Charging: " + BatteryManager.BATTERY_STATUS_CHARGING,
"Battery Status Discharging: " + BatteryManager.BATTERY_STATUS_DISCHARGING, 
"Battery Status Full: " + BatteryManager.BATTERY_STATUS_FULL,
        "Battery Status Unknown: " + BatteryManager.BATTERY_STATUS_UNKNOWN, 
"Battery Health: " + "",
"Battery Icon Small: " + BatteryManager.EXTRA_ICON_SMALL, "Battery Level: " 
+ BatteryManager.EXTRA_LEVEL, "Is Battery Plugged: " + 
BatteryManager.EXTRA_PLUGGED,
"Is Battery Present: " + BatteryManager.EXTRA_PRESENT, "Battery Scale: " + 
BatteryManager.EXTRA_SCALE, "Battery Status: " + 
BatteryManager.EXTRA_STATUS,
"Battery Technology: " + BatteryManager.EXTRA_TECHNOLOGY, "Battery 
Temperature: " + BatteryManager.EXTRA_TEMPERATURE, "Battery Voltage: " +   
BatteryManager.EXTRA_VOLTAGE};
*/
private ListView batteryPropsView;
private ArrayAdapter arrayAdapter;


@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {

    //Bundle bundle = this.getArguments();
    int myValue = getArguments().getInt("message");


    String [] batteryProperties = {"Battery Plugged AC: " + 
BatteryManager.BATTERY_PLUGGED_AC,
            "Battery Plugged USB: " + BatteryManager.BATTERY_PLUGGED_USB, 
"Battery Plugged Wireless: " + BatteryManager.BATTERY_PLUGGED_WIRELESS,
            "Battery Capacity: " + BatteryManager.BATTERY_PROPERTY_CAPACITY, 
"Battery Charge Counter: " + BatteryManager.BATTERY_PROPERTY_CHARGE_COUNTER,
            "Battery Current Average: " + 
BatteryManager.BATTERY_PROPERTY_CURRENT_AVERAGE, "Battery Current Now: " + 
BatteryManager.BATTERY_PROPERTY_CURRENT_NOW,
            "Battery Energy Counter: " + 
BatteryManager.BATTERY_PROPERTY_ENERGY_COUNTER, "Battery Status Charging: " 
+ BatteryManager.BATTERY_STATUS_CHARGING,
            "Battery Status Discharging: " + 
BatteryManager.BATTERY_STATUS_DISCHARGING, "Battery Status Full: " + 
BatteryManager.BATTERY_STATUS_FULL,
            "Battery Status Unknown: " + 
BatteryManager.BATTERY_STATUS_UNKNOWN, "Battery Health: " + myValue,
            "Battery Icon Small: " + BatteryManager.EXTRA_ICON_SMALL, 
"Battery Level: " + BatteryManager.EXTRA_LEVEL, "Is Battery Plugged: " + 
BatteryManager.EXTRA_PLUGGED,
            "Is Battery Present: " + BatteryManager.EXTRA_PRESENT, "Battery 
Scale: " + BatteryManager.EXTRA_SCALE, "Battery Status: " + 
BatteryManager.EXTRA_STATUS,
            "Battery Technology: " + BatteryManager.EXTRA_TECHNOLOGY, 
"Battery Temperature: " + BatteryManager.EXTRA_TEMPERATURE, "Battery 
Voltage: " + BatteryManager.EXTRA_VOLTAGE};
    View rootView = inflater.inflate(R.layout.fragment_batteryinfo, 
container, false);
    batteryPropsView = (ListView) rootView.findViewById(R.id.batteryInfo);

    arrayAdapter = new ArrayAdapter(getActivity(), 
android.R.layout.simple_list_item_1, batteryProperties);
    batteryPropsView.setAdapter(arrayAdapter);



    batteryPropsView.setOnItemLongClickListener(new 
AdapterView.OnItemLongClickListener() {
        @Override
        public boolean onItemLongClick(AdapterView<?> parent, View view, int 
position,
                                       long id) {
            Toast.makeText(getActivity(), "You clicked on an item.", 
Toast.LENGTH_SHORT).show();
            return true;
        }
    });
    return rootView;
}


}

我的活动代码：

package natanrosenfeld.systeminfo;

/**
* Created by natanrosenfeld on 6/19/15.
*/
import android.app.Activity;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.BatteryManager;
import android.os.Bundle;
import android.widget.ImageView;
import android.widget.TextView;



public class BatteryStatsActivity extends Activity {
private TextView batteryInfo;
private ImageView imageBatteryState;
/** Called when the activity is first created. */
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    this.registerReceiver(this.batteryInfoReceiver, new  
IntentFilter(Intent.ACTION_BATTERY_CHANGED));


}


private BroadcastReceiver batteryInfoReceiver = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {

        int  health= intent.getIntExtra(BatteryManager.EXTRA_HEALTH,0);
        int  icon_small= intent.getIntExtra(BatteryManager.EXTRA_ICON_SMALL,0);
        int  level= intent.getIntExtra(BatteryManager.EXTRA_LEVEL,0);
        int  plugged= intent.getIntExtra(BatteryManager.EXTRA_PLUGGED, 0);
        boolean  present= intent.getExtras().getBoolean(BatteryManager.EXTRA_PRESENT);
        int  scale= intent.getIntExtra(BatteryManager.EXTRA_SCALE, 0);
        int  status= intent.getIntExtra(BatteryManager.EXTRA_STATUS, 0);
        String  technology= intent.getExtras().getString(BatteryManager.EXTRA_TECHNOLOGY);
        int  temperature= intent.getIntExtra(BatteryManager.EXTRA_TEMPERATURE, 0);
        int  voltage= intent.getIntExtra(BatteryManager.EXTRA_VOLTAGE, 0);


        Bundle bundle = new Bundle();
        bundle.putInt("message", health);
        // set Fragmentclass Arguments
        BatteryInfoFragment fragobj = new BatteryInfoFragment();
        fragobj.setArguments(bundle);
        getFragmentManager().beginTransaction()
        .addToBackStack(null)
        .commit();


        batteryInfo.setText(
                "Health: "+health+"\n"+
                        "Icon Small:"+icon_small+"\n"+
                        "Level: "+level+"\n"+
                        "Plugged: "+plugged+"\n"+
                        "Present: "+present+"\n"+
                        "Scale: "+scale+"\n"+
                        "Status: "+status+"\n"+
                        "Technology: "+technology+"\n"+
                        "Temperature: "+temperature+"\n"+
                        "Voltage: "+voltage+"\n");
        imageBatteryState.setImageResource(icon_small);
    }
};


}

任何帮助将不胜感激！我不想再花一天时间在我的应用程序的这一部分！谢谢！

Answer 1

从活动中您按意图发送数据：

Bundle bundle = new Bundle();
bundle.putString("edttext", "From Activity");

// set Fragmentclass Arguments

Fragmentclass fragobj = new Fragmentclass();

fragobj.setArguments(bundle);

并在Fragment onCreateView方法中：

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
    Bundle savedInstanceState) {
String strtext = getArguments().getString("edttext");    
return inflater.inflate(R.layout.fragment, container, false);
}

Android - 将数据从Activity传递到Fragment

1 个答案: