java - 添加额外类时找不到 Android 源

Question

我已经浏览了所有其他有此问题的帖子，但无济于事。

我创建了一个应用程序，当所有代码都位于 MainActivity 内部时，该应用程序可以完美运行，但是当我创建一个类来检查 GPS 并清理 MainActivity 源文件时，我在调试时收到错误消息“未找到来源”。

对于这个问题，我是 android 和 java 的新手(我通常使用 c 和 c++)，所以我不知道这是否与我的 manifest.xml 等有关，但这让我发疯!

我在下面包含了我的代码以及我的manifest.xml 文件。

当逐行检查我的代码时，出现此错误的行是 final LocationManager manager = (LocationManager) getSystemService(LOCATION_SERVICE);

GpsCheck.java

package com.omegaapp.openomega;

import android.os.*;
import android.location.*;
import android.location.GpsStatus.Listener;
import android.app.*;
import android.content.*;
import com.omegaapp.*;



public class GpsCheck extends android.app.Activity{

    public GpsCheck(){
        final LocationManager manager =  (LocationManager) getSystemService(LOCATION_SERVICE);
        Listener gpsStatusListener = new Listener(){
            @Override
            public void onGpsStatusChanged(int arg0) {
                gpsEnable();

            }
        };
        manager.addGpsStatusListener(gpsStatusListener);
    }

    public boolean gpsEnable(){
        //checks weather the GPS is enabled. If not, prompts the user to enable it then checks again. Returns false if the user chooses not to enable the application.
        if(!checkGpsEnabled()){
            promptEnableGps();
        }
        return true;
    }

    private boolean checkGpsEnabled(){
        final LocationManager manager =  (LocationManager) getSystemService(LOCATION_SERVICE);
        if ( !manager.isProviderEnabled( LocationManager.GPS_PROVIDER ) ) {
            return false;
        }
        return true;
    }

    private boolean promptNoGpsQuit(){
        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);
        alertDialogBuilder.setMessage("Without enabling GPS this app can not function, Would you like to quit?");
        alertDialogBuilder.setCancelable(false);
        DialogInterface.OnClickListener onClick = new DialogInterface.OnClickListener(){
            public void onClick(DialogInterface dialog, int id){
                Intent callGPSSettingIntent = new Intent(
                android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                startActivity(callGPSSettingIntent);
            }
        };
        alertDialogBuilder.setPositiveButton("Goto Settings Page To Enable GPS", onClick);

        DialogInterface.OnClickListener onClickCancel = new DialogInterface.OnClickListener(){
            public void onClick(DialogInterface dialog, int id){
                dialog.cancel();
                finish();
            }
        };
        alertDialogBuilder.setNegativeButton("Quit", onClickCancel);
        AlertDialog alert = alertDialogBuilder.create();
        alert.show();
        return true;
    }

    private boolean promptEnableGps(){
        AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);
        alertDialogBuilder.setMessage("GPS is disabled in your device. Would you like to enable it?");
        alertDialogBuilder.setCancelable(false);
        DialogInterface.OnClickListener onClick = new DialogInterface.OnClickListener(){
            public void onClick(DialogInterface dialog, int id){
                Intent callGPSSettingIntent = new Intent(
                android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                startActivity(callGPSSettingIntent);
            }
        };
        alertDialogBuilder.setPositiveButton("Goto Settings Page To Enable GPS", onClick);

        DialogInterface.OnClickListener onClickCancel = new DialogInterface.OnClickListener(){
            public void onClick(DialogInterface dialog, int id){
                dialog.cancel();
                promptNoGpsQuit();
            }
        };
        alertDialogBuilder.setNegativeButton("Cancel", onClickCancel);
        AlertDialog alert = alertDialogBuilder.create();
        alert.show();
        return true;
    }

}

Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.omegaapp.openomega"
android:versionCode="1"
android:versionName="1.0" >

<uses-sdk
    android:minSdkVersion="8"
    android:targetSdkVersion="16" />
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
<uses-permission android:name="android.permission.RECEIVE_BOOT_COMPLETED"/>

<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name="com.omegaapp.openomega.MainActivity"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>
    <receiver android:enabled="true" android:name=".BootUpReceiver"
        android:permission="android.permission.RECEIVE_BOOT_COMPLETED">

        <intent-filter>
                <action android:name="android.intent.action.BOOT_COMPLETED" />
                <category android:name="android.intent.category.DEFAULT" />
        </intent-filter>
    </receiver>
</application>

谢谢!

Answer 1

这里

public class GpsCheck extends android.app.Activity{

    public GpsCheck(){

  }
      your code  .....
}

这不是创建非 Activity 类来获取 Activity 上下文的正确方法。您需要将 Activity Context 传递给非 Activity 类以访问系统服务或其他 Activity 或应用程序组件

通过将 Context 传递给 GpsCheck 构造函数来更改您的 GpsCheck，使其正常工作:

public class GpsCheck{
   Context context;
    LocationManager manager;

    public GpsCheck(Context context){
     this.context=context;

     this.manager =  (LocationManager)context.getSystemService(LOCATION_SERVICE);
     //your code here
    }
      your code  .....
}

并从您的 Activity 中发送当前 Activity 上下文:

GpsCheck gpscheckobj=new GpsCheck(MainActivity.this);