我是在Android Studio中开发Java的新手，所以我通过以下教程学习。我现在正在创建一个控制机器人的应用程序，我想实现蓝牙功能。所以我使用Harry的教程Harry's tutorial开始了关于蓝牙的教程。
在学习了一些Android Studio知识之后，我创建了不同的片段而不是多重活动。现在的问题是，在致电ArrayAdapter.add();时我会受到打击。这个函数收到一个String wright？那么为什么我的应用程序总是崩溃，调用mPairedDevicesArrayAdapter.add(deviceString)。
调试代码时，程序可以很好地获取设备名称和MAC地址。它在调试监视器中记录得很好，所以deviceString不是问题吗？其他人说你需要把String放到一个列表中，但Android文档说当调用正确的构造函数时它只能接收一个String。
有人可以帮我解决这个问题。这是我的bluetoothFragment类和.xml文件。
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.content.Intent;
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.TextView;
import android.widget.Toast;
import java.util.ArrayList;
import java.util.Set;
/**
* Created by rbesten on 5/2/2017.
*/
public class BluetoothFragment extends Fragment {
// textview for connection status
TextView textConnectionStatus;
ListView pairedListView;
//An EXTRA to take the device MAC to the next activity
public static String EXTRA_DEVICE_ADDRESS;
// Member fields
private BluetoothAdapter mBtAdapter;
private ArrayAdapter<String> mPairedDevicesArrayAdapter;
String deviceString = "Test if it works";
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate( R.layout.fragment_bluetooth, container, false );
return rootView;
}
public void onActivityCreated(Bundle savedInstanceState){
super.onActivityCreated(savedInstanceState);
textConnectionStatus = (TextView) getActivity().findViewById(R.id.connecting);
textConnectionStatus.setTextSize(40);
//Initialize array adapter for paired devices
mPairedDevicesArrayAdapter = new ArrayAdapter<String>(getContext(), R.layout.device_name);
// Find and set up the ListView for paired devices
pairedListView = (ListView) getActivity().findViewById(R.id.paired_devices);
pairedListView.setAdapter(mPairedDevicesArrayAdapter);
//pairedListView.setOnItemClickListener(mDeviceClickListener);
}
@Override
public void onResume() {
super.onResume();
//check BT status at onResume in case something has changed while app was paused etc
checkBTState();
mPairedDevicesArrayAdapter.clear();// clears the array so items aren't duplicated when resuming from onPause
textConnectionStatus.setText(" "); //makes the textview blank
//Get the local Bluetooth adapter
mBtAdapter = BluetoothAdapter.getDefaultAdapter();
// Get a set of currently paired devices and append to pairedDevices list
Set<BluetoothDevice> pairedDevices = mBtAdapter.getBondedDevices();
// Add previously paired devices to the array
if (pairedDevices.size() > 0) {
getActivity().findViewById(R.id.title_paired_devices).setVisibility(View.VISIBLE );//make title viewable
for(BluetoothDevice device : pairedDevices){
deviceString = (device.getName() + "\n" + device.getAddress() );
mPairedDevicesArrayAdapter.add(deviceString);
mPairedDevicesArrayAdapter.notifyDataSetChanged();
}
} else {
mPairedDevicesArrayAdapter.add("no devices paired");
mPairedDevicesArrayAdapter.notifyDataSetChanged();
}
}
//method to check if the device has Bluetooth and if it is on.
//Prompts the user to turn it on if it is off
private void checkBTState() {
// Check device has Bluetooth and that it is turned on
mBtAdapter = BluetoothAdapter.getDefaultAdapter(); // CHECK THIS OUT THAT IT WORKS!!!
if (mBtAdapter == null) {
Toast.makeText( getActivity().getBaseContext(), "Device does not support Bluetooth", Toast.LENGTH_SHORT ).show();
getActivity().finish();
} else {
if (!mBtAdapter.isEnabled()) {
//Prompt user to turn on Bluetooth
Intent enableBtIntent = new Intent( BluetoothAdapter.ACTION_REQUEST_ENABLE );
startActivityForResult( enableBtIntent, 1 );
}
}
}
和.XML文件！
<?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/title_paired_devices"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge"
android:text="Select btSerial device from paired devices:"
android:visibility="gone"
android:background="#666"
android:textColor="#fff"
android:paddingLeft="5dp" />
<ListView
android:id="@+id/paired_devices"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:stackFromBottom="false"
android:layout_weight="1" />
<TextView
android:id="@+id/connecting"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceLarge" />
<TextView
android:id="@+id/infoText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="If no devices are listed please pair your device in Android settings"
android:textAppearance="?android:attr/textAppearanceLarge" />
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center">
</LinearLayout>
</LinearLayout>
调试器信息是：
this = {BluetoothFragment@4820} "BluetoothFragment{4e73664 #3 id=0x7f0b005e android:switcher:2131427422:3}"
pairedDevices = {Collections$UnmodifiableSet@4822} size = 2
device = {BluetoothDevice@4823} "50:32:75:DA:15:4A"
mPairedDevicesArrayAdapter = {ArrayAdapter@4824}
mBtAdapter = {BluetoothAdapter@4825}
deviceString = "Test if it works"
崩溃日志：
05-03 10:10:32.364 32255-32255/com.example.rbesten.solscanrobot D/AndroidRuntime: Shutting down VM
05-03 10:10:32.367 32255-32255/com.example.rbesten.solscanrobot E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.rbesten.solscanrobot, PID: 32255
java.lang.IllegalStateException: ArrayAdapter requires the resource ID to be a TextView
at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:401)
at android.widget.ArrayAdapter.getView(ArrayAdapter.java:371)
at android.widget.AbsListView.obtainView(AbsListView.java:2494)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1349)
at android.widget.ListView.onMeasure(ListView.java:1250)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1705)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:797)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:657)
at android.view.View.measure(View.java:20084)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1658)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:214)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:393)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:214)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1705)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:797)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:657)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:214)
at com.android.internal.policy.DecorView.onMeasure(DecorView.java:766)
at android.view.View.measure(View.java:20084)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2640)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1577)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1846)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1462)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6965)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:907)
at android.view.Choreographer.doCallbacks(Choreographer.java:709)
at android.view.Choreographer.doFrame(Choreographer.java:644)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:893)
at android.os.Handler.handleCallback(Handler.java:836)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:203)
at android.app.ActivityThread.main(ActivityThread.java:6247)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)
Caused by: java.lang.ClassCastException: android.widget.LinearLayout cannot be cast to android.widget.TextView
at android.widget.ArrayAdapter.createViewFromResource(ArrayAdapter.java:388)
at android.widget.ArrayAdapter.getView(ArrayAdapter.java:371)
at android.widget.AbsListView.obtainView(AbsListView.java:2494)
at android.widget.ListView.measureHeightOfChildren(ListView.java:1349)
at android.widget.ListView.onMeasure(ListView.java:1250)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1705)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:797)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:657)
at android.view.View.measure(View.java:20084)
at android.support.v4.view.ViewPager.onMeasure(ViewPager.java:1658)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:214)
at android.support.v7.widget.ContentFrameLayout.onMeasure(ContentFrameLayout.java:139)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.support.v7.widget.ActionBarOverlayLayout.onMeasure(ActionBarOverlayLayout.java:393)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:214)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.widget.LinearLayout.measureChildBeforeLayout(LinearLayout.java:1705)
at android.widget.LinearLayout.measureVertical(LinearLayout.java:797)
at android.widget.LinearLayout.onMeasure(LinearLayout.java:657)
at android.view.View.measure(View.java:20084)
at android.view.ViewGroup.measureChildWithMargins(ViewGroup.java:6282)
at android.widget.FrameLayout.onMeasure(FrameLayout.java:214)
at com.android.internal.policy.DecorView.onMeasure(DecorView.java:766)
at android.view.View.measure(View.java:20084)
at android.view.ViewRootImpl.performMeasure(ViewRootImpl.java:2640)
at android.view.ViewRootImpl.measureHierarchy(ViewRootImpl.java:1577)
at android.view.ViewRootImpl.performTraversals(ViewRootImpl.java:1846)
at android.view.ViewRootImpl.doTraversal(ViewRootImpl.java:1462)
at android.view.ViewRootImpl$TraversalRunnable.run(ViewRootImpl.java:6965)
at android.view.Choreographer$CallbackRecord.run(Choreographer.java:907)
at android.view.Choreographer.doCallbacks(Choreographer.java:709)
at android.view.Choreographer.doFrame(Choreographer.java:644)
at android.view.Choreographer$FrameDisplayEventReceiver.run(Choreographer.java:893)
at android.os.Handler.handleCallback(Handler.java:836)
at android.os.Handler.dispatchMessage(Handler.java:103)
at android.os.Looper.loop(Looper.java:203)
at android.app.ActivityThread.main(ActivityThread.java:6247)
at java.lang.reflect.Method.invoke(Native Method)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)
在device_name布局中：
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textSize="18sp"
android:padding="5dp">
</TextView>
</LinearLayout>
答案 0 :(得分：0)
R.layout.device_name必须是仅包含TextView的xml布局文件的id（TextView不能被其他布局包装，如LinearLayout，RelativeLayout等！），如下所示：
有关详细信息，请参阅以下链接 "ArrayAdapter requires the resource ID to be a TextView" xml problems
或者您可以在数组适配器构造函数中尝试使用以下id进行测试 android.R.layout.simple_list_item_1代替R.layout.device_name
希望能帮到你