Question

我是Android开发的新手，我试图在列表中显示广播蓝牙信号的设备列表。

MainActivity.java

public class MainActivity extends ListActivity {
    private BluetoothManager bManager;
    private BluetoothAdapter bAdap;
    private listViewAdapter lvAdap;
    private Handler mHandler;
    private boolean bScanning;
    private static long SCAN_PERIOD = 10000;
    private TextView tv;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        bManager = (BluetoothManager)getSystemService(BLUETOOTH_SERVICE);
        bAdap = bManager.getAdapter();
        bScanning = false;
        mHandler = new Handler();
        tv = (TextView)findViewById(R.id.textView);
    lvAdap = new listViewAdapter(this);
    ListView lv = (ListView)findViewById(R.id.listView);
    lv.setAdapter(lvAdap);
}
@Override
protected void onResume() {
    super.onResume();
    if(!bAdap.isEnabled())
    {
        Intent enableBT = new Intent(bAdap.ACTION_REQUEST_ENABLE);
        startActivityForResult(enableBT,1);
    }
    scanLeDevice(true);
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // User chose not to enable Bluetooth.
    if (requestCode == 1 && resultCode == Activity.RESULT_CANCELED) {
        finish();
        return;
    }
    super.onActivityResult(requestCode, resultCode, data);
}

@Override
protected void onPause() {
    super.onPause();
    scanLeDevice(false);
    lvAdap.clear();
}

/*
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
*/

//List adapter for displaying Bluetooth device name and address
public class listViewAdapter extends BaseAdapter
{
    private Context mContext;
    private LayoutInflater mLayInflat;
    private ArrayList<BluetoothDevice> bDeviceArray = new ArrayList<BluetoothDevice>();

    public listViewAdapter(Context context)
    {
        mContext = context;
        mLayInflat = (LayoutInflater)mContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
    }

    public void addDevice(BluetoothDevice device)
    {
        if(!bDeviceArray.contains(device))
        {
            bDeviceArray.add(device);
        }
    }

    public BluetoothDevice getDevice(int position)
    {
        return bDeviceArray.get(position);
    }

    @Override
    public int getCount() {
        return bDeviceArray.size();
    }

    public void clear()
    {
        bDeviceArray.clear();
    }

    @Override
    public Object getItem(int i)
    {
        return bDeviceArray.get(i);
    }

    @Override
    public long getItemId(int i)
    {
        return i;
    }

    @Override
    public View getView(int i, View convertView, ViewGroup parent) {
        LinearLayout itemView;

        if(convertView == null)
        {
            itemView = (LinearLayout)mLayInflat.inflate(R.layout.list,parent,false);
        }
        else
        {
            itemView = (LinearLayout)convertView;
        }
        TextView dNameText = (TextView)itemView.findViewById(R.id.device_name);
        TextView dAddresstext = (TextView)itemViewfindViewById(R.id.device_address);

        BluetoothDevice device = bDeviceArray.get(i);
        final String deviceName = device.getName();
        if(deviceName != null || deviceName.length()>0)
            dNameText.setText(deviceName);
        else
            dNameText.setText("UNKNOWN DEVICE");
        dAddresstext.setText(device.getAddress());
        return itemView;
    }
}

private void scanLeDevice(final boolean enable) {
    if (enable) {
        // Stops scanning after a pre-defined scan period.
        mHandler.postDelayed(new Runnable() {
            @Override
            public void run() {
                bScanning = false;
                tv.setText("Stopped scanning!");
                bAdap.stopLeScan(mLeScanCallback);
                invalidateOptionsMenu();
            }
        }, SCAN_PERIOD);
        tv.setText("Scanning...");
        bScanning = true;
        bAdap.startLeScan(mLeScanCallback);
    } else {
        bScanning = false;
        bAdap.stopLeScan(mLeScanCallback);
    }
    invalidateOptionsMenu();
}

private BluetoothAdapter.LeScanCallback mLeScanCallback =
        new BluetoothAdapter.LeScanCallback() {

            @Override
            public void onLeScan(final BluetoothDevice device, int rssi, byte[] scanRecord) {
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        lvAdap.addDevice(device);
                        lvAdap.notifyDataSetChanged();
                    }
                });
            }
        };

}

list.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" android:layout_width="match_parent"
    android:layout_height="match_parent">
<TextView
    android:id="@+id/device_name"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textSize="24sp"/>
<TextView
    android:id="@+id/device_address"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:paddingLeft="10dp"
    android:textSize="14sp"/>
</LinearLayout>

main.xml中

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    tools:context="com.newP.inflatetest.MainActivity">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textAppearance="?android:attr/textAppearanceLarge"
        android:text="Scanning..."
        android:id="@+id/textView" />
    <ListView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/textView"
        android:id="@+id/listView" />
</RelativeLayout>

的AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.newP.inflatetest">
    <uses-permission android:name="android.permission.BLUETOOTH"/>
    <uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
    <uses-permission android:name="android.permission.BLUETOOTH_ADMIN"/>
    <uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
    <uses-feature android:name="android.hardware.bluetooth_le" android:required="true"/>
    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:supportsRtl="true"
        android:theme="@style/AppTheme">
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name"
            android:theme="@android:style/Theme.Material.Light.DarkActionBar">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>

我已经包含了所有必要的

进口。由于仿真器不支持蓝牙，我将其部署在手机中。

我不知道究竟是什么错误。每当我尝试启动它时，应用程序都会崩溃。

我通过DDMS收到了此错误消息。

java.lang.RuntimeException：无法启动活动 ComponentInfo {com.newP.inflatetest / com.newP.inflatetest.MainActivity}： java.lang.RuntimeException：您的内容必须具有其id为的ListView 属性是＆＃39; android.R.id.list＆＃39;

任何帮助都会很棒。谢谢。

Answer 1

您似乎正在使用ListActivity并且您没有在布局中将ListView设置为id，而您尚未定义list元素使用

尝试将public class MainActivity extends ListActivity更改为public class MainActivity extends Activity。

或者，将ListActivity元素的ID更改为android:id="@+id/list"，并在您的活动中删除lv变量的声明，然后只需致电setListAdapter(lvAdap);

这个Android蓝牙代码有什么错误？

1 个答案: