我尝试使用setAdapter()制作蓝牙应用并遇到麻烦。
private BluetoothAdapter BA;
ListView listB;
private Set<BluetoothDevice> pairedDevices;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
BA = BluetoothAdapter.getDefaultAdapter();
listB = (ListView)findViewById(R.id.listBlu);
if (!BA.isEnabled()) {
Intent blu_turn_on = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(blu_turn_on, 0);
Toast.makeText(getApplicationContext(),"Bluetooth turn on",Toast.LENGTH_SHORT).show();
Set<BluetoothDevice> pariedDevices;
pariedDevices = BA.getBondedDevices();
}
else
{
Toast.makeText(getApplicationContext(),"Bluetooth already on", Toast.LENGTH_SHORT).show();
}
Intent getVisible = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
startActivityForResult(getVisible, 0);
pairedDevices = BA.getBondedDevices();
ArrayList list = new ArrayList();
for(BluetoothDevice bt : pairedDevices)
list.add(bt.getName());
Toast.makeText(getApplicationContext(),"Showing Paired Devices",Toast.LENGTH_SHORT).show();
final ListAdapter adapter = new ArrayAdapter(this,android.R.layout.simple_list_item_1, list);
listB.setAdapter(adapter);
}
04-20 21:52:15.761 17597-17597/com.example.werewolf.deltacontroler W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
04-20 21:52:16.074 17597-17765/com.example.werewolf.deltacontroler D/OpenGLRenderer: Use EGL_SWAP_BEHAVIOR_PRESERVED: true
04-20 21:52:16.085 17597-17597/com.example.werewolf.deltacontroler D/Atlas: Validating map...
04-20 21:52:16.201 17597-17765/com.example.werewolf.deltacontroler I/Adreno-EGL: <qeglDrvAPI_eglInitialize:410>: EGL 1.4 QUALCOMM build: AU_LINUX_ANDROID_LA.AF.1.1_RB1.05.00.02.006.020_msm8960_LA.AF.1.1_RB1__release_AU ()
OpenGL ES Shader Compiler Version: E031.25.03.06
Build Date: 05/22/15 Fri
Local Branch: mybranch10237523
Remote Branch: quic/LA.AF.1.1_rb1.18
Local Patches: NONE
Reconstruct Branch: AU_LINUX_ANDROID_LA.AF.1.1_RB1.05.00.02.006.020 + 9b2699f + 2215637 + 60aa592 + f2362e6 + 5c64f59 + 82411a1 + 89a0db6 + 6151be1 + NOTHING
04-20 21:52:16.210 17597-17765/com.example.werewolf.deltacontroler I/OpenGLRenderer: Initialized EGL, version 1.4
04-20 21:52:16.260 17597-17765/com.example.werewolf.deltacontroler D/OpenGLRenderer: Enabling debug mode 0
04-20 21:52:16.535 17597-17597/com.example.werewolf.deltacontroler I/Timeline: Timeline: Activity_idle id: android.os.BinderProxy@31ae5690 time:79315035
04-20 21:52:42.340 17597-17597/com.example.werewolf.deltacontroler I/Timeline: Timeline: Activity_launch_request id:com.example.werewolf.deltacontroler time:79340840
04-20 21:52:42.495 17597-17597/com.example.werewolf.deltacontroler D/BluetoothAdapter: 850763313: getState() : mService = null. Returning STATE_OFF
04-20 21:52:42.501 17597-17597/com.example.werewolf.deltacontroler D/BluetoothAdapter: 850763313: getState() : mService = null. Returning STATE_OFF
04-20 21:52:42.507 17597-17597/com.example.werewolf.deltacontroler D/AndroidRuntime: Shutting down VM
04-20 21:52:42.514 17597-17597/com.example.werewolf.deltacontroler E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.werewolf.deltacontroler, PID: 17597
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.werewolf.deltacontroler/com.example.werewolf.deltacontroler.Configuration}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2442)
at android.app.ActivityThread.access$800(ActivityThread.java:156)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1351)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:211)
at android.app.ActivityThread.main(ActivityThread.java:5389)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1020)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:815)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at com.example.werewolf.deltacontroler.Configuration.onCreate(Configuration.java:51)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2332)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2442)
at android.app.ActivityThread.access$800(ActivityThread.java:156)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1351)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:211)
at android.app.ActivityThread.main(ActivityThread.java:5389)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1020)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:815)
04-20 21:52:49.245 18952-18952/com.example.werewolf.deltacontroler I/Process: Sending signal. PID: 18952 SIG: 9
04-20 21:52:49.512 19066-19066/com.example.werewolf.deltacontroler W/ResourceType: Found multiple library tables, ignoring...
04-20 21:52:49.522 19066-19066/com.example.werewolf.deltacontroler W/ResourceType: Found multiple library tables, ignoring...
04-20 21:52:49.859 19066-19066/com.example.werewolf.deltacontroler W/art: Before Android 4.1, method android.graphics.PorterDuffColorFilter android.support.graphics.drawable.VectorDrawableCompat.updateTintFilter(android.graphics.PorterDuffColorFilter, android.content.res.ColorStateList, android.graphics.PorterDuff$Mode) would have incorrectly overridden the package-private method in android.graphics.drawable.Drawable
04-20 21:52:50.172 19066-19066/com.example.werewolf.deltacontroler D/BluetoothAdapter: 132902748: getState() : mService = null. Returning STATE_OFF
04-20 21:52:50.194 19066-19066/com.example.werewolf.deltacontroler D/BluetoothAdapter: 132902748: getState() : mService = null. Returning STATE_OFF
04-20 21:52:50.206 19066-19066/com.example.werewolf.deltacontroler D/AndroidRuntime: Shutting down VM
04-20 21:52:50.208 19066-19066/com.example.werewolf.deltacontroler E/AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.werewolf.deltacontroler, PID: 19066
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.werewolf.deltacontroler/com.example.werewolf.deltacontroler.Configuration}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2379)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2442)
at android.app.ActivityThread.access$800(ActivityThread.java:156)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1351)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:211)
at android.app.ActivityThread.main(ActivityThread.java:5389)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1020)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:815)
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ListView.setAdapter(android.widget.ListAdapter)' on a null object reference
at com.example.werewolf.deltacontroler.Configuration.onCreate(Configuration.java:51)
at android.app.Activity.performCreate(Activity.java:5990)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1106)
at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2332)
at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2442)
at android.app.ActivityThread.access$800(ActivityThread.java:156)
at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1351)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:211)
at android.app.ActivityThread.main(ActivityThread.java:5389)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1020)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:815)
04-20 21:52:51.591 19066-19066/com.example.werewolf.deltacontroler I/Process: Sending signal. PID: 19066 SIG: 9
应用程序运行正常，但只要输入此部分代码就会崩溃。
问题出在setAdapter()的最后一行，因为如果我从代码应用程序中删除它，则通常会在结果空窗口中输入。
我试图寻找解决方案，但似乎每个人都这样做，我无法发现我的错误。