如何从其他

Question

在我的Android项目一类的调用对象是有MainActivity.java

MainActivity extends FragmentActivity{ 

    onCreate(Bundle savedInstanceState){ 

     BluetoothManager bluetoothManager = 
       (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE); 
     mBluetoothAdapter = bluetoothManager.getAdapter(); 

    } 
    } 

如何使用mBluetoothAdapter对象在下面的类

public class AvailableDevices extends ListFragment { 

    // How to call mBluetoothAdapter here 
    } 

感谢

Answer 1

传递作为参数的类

public class AvailableDevices extends ListFragment { 
    private BluetoothAdapter bluetoothAdapter; 
    public AvailableDevices(BluetoothAdapter bluetoothAdapter) { 
     this.bluetoothAdapter = bluetoothAdapter; 
    } 
} 

的构造或声明为静态公共数据成员

public class MainActivity extends FragmentActivity{ 

    public static BluetoothAdapter mBluetoothAdapter; 

    .. 
} 

，然后在其他类使用MainActivity.mBluetoothAdapter

或使AvailableDevices成为内部类并将适配器声明为数据成员：

public class MainActivity extends FragmentActivity{ 

    private BluetoothAdapter mBluetoothAdapter; 
    .. 
    class AvailableDevices extends ListFragment { 
     //can use mBluetoothAdapter 
    } 
} 

Answer 2

申报在类级别（在onCreate（）方法之前）的BluetoothManager bluetoothManager和其他类应该是内部类

Answer 3

There are two ways known to me- 

Using Static variable: 

MainActivity extends FragmentActivity{ 
public static BluetoothAdapter mBluetoothAdapter; 
    onCreate(Bundle savedInstanceState){ 

     BluetoothManager bluetoothManager = 
       (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE); 
     mBluetoothAdapter = bluetoothManager.getAdapter(); 

    } 
    } 

public class AvailableDevices extends ListFragment { 

    // How to call mBluetoothAdapter here 
    use in this class as MainActivity.mBluetoothAdapter 

    } 


2.Passing mBluetoothAdapter to the constructor of the second class. 

MainActivity extends FragmentActivity{ 

    onCreate(Bundle savedInstanceState){ 

     BluetoothManager bluetoothManager = 
       (BluetoothManager) getSystemService(Context.BLUETOOTH_SERVICE); 
     mBluetoothAdapter = bluetoothManager.getAdapter(); 

    } 
    } 

public class AvailableDevices extends ListFragment { 
    BluetoothAdapter mBluetoothAdapter=null; 
AvailableDevices(BluetoothAdapter mBluetoothAdapter){ 
    this.mBluetoothAdapter=mBluetoothAdapter; 


    }