想用远程蓝牙服务器实现数据传输，于是开始探索androids蓝牙功能，一步步走，现在卡在一个程序里。将程序加载到模拟器后，它会响应“Adil_Bluetooth_1st 已停止”。
我为您提供我的文件：
XML 文件：
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity" >
<TextView
android:id="@+id/acceleration"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:text="X: Y: Z:"
android:textAppearance="?android:attr/textAppearanceLarge" />
<ProgressBar
android:id="@+id/progressBarX"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/acceleration"
android:layout_alignParentRight="true"
android:layout_below="@+id/acceleration"
android:layout_marginLeft="19dp"
android:layout_marginRight="19dp"
android:layout_marginTop="40dp" />
<TextView
android:id="@+id/textView1"
android:layout_width="140dp"
android:layout_height="wrap_content"
android:layout_alignRight="@+id/progressBarX"
android:layout_alignTop="@+id/acceleration"
android:text=" Noise Margin" />
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/progressBarX"
android:layout_below="@+id/progressBarX"
android:text="X-axis" />
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/progressBarZ"
android:layout_below="@+id/progressBarY"
android:text="Y-axis" />
<ProgressBar
android:id="@+id/progressBarY"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/textView2"
android:layout_alignRight="@+id/progressBarX"
android:layout_below="@+id/textView2"
android:layout_marginTop="72dp" />
<EditText
android:id="@+id/eText"
android:layout_width="50dp"
android:layout_height="45dp"
android:layout_alignLeft="@+id/textView1"
android:layout_alignTop="@+id/textView1"
android:ems="10"
android:inputType="numberDecimal" >
<requestFocus />
</EditText>
<TextView
android:id="@+id/textView4"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/progressBarZ"
android:layout_alignTop="@+id/progressBarZ"
android:layout_marginTop="20dp"
android:text="Z-axis" />
<ProgressBar
android:id="@+id/progressBarZ"
style="?android:attr/progressBarStyleHorizontal"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="@+id/progressBarY"
android:layout_alignRight="@+id/progressBarY"
android:layout_below="@+id/textView3"
android:layout_marginTop="84dp" />
</RelativeLayout>
这是我的ActivityMain.java文件：
package com.example.adil_bluetooth_1st;
import java.util.Set;
import javax.xml.datatype.Duration;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.widget.ArrayAdapter;
import android.widget.Toast;
import android.bluetooth.*;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
public class Bluetooth extends Activity {
private BluetoothAdapter mBluetoothAdapter;
Integer REQ_BT_ENABLE=1;
private ArrayAdapter<String> mArrayAdapter;
Set<BluetoothDevice> pairedDevices;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_bluetooth);
mBluetoothAdapter=BluetoothAdapter.getDefaultAdapter();
String Status;
if(mBluetoothAdapter==null)
{
Toast.makeText(this, "Device doesn't support Bluetooth", Toast.LENGTH_LONG).show();
}
/*
* checking whether Bluetooth is enabled ,if not enable it!
* */
if(mBluetoothAdapter.isEnabled())
{
String mydeviceadress=mBluetoothAdapter.getAddress();
String mydevicename=mBluetoothAdapter.getName();
Status="My Device Name is:"+mydevicename+"\nThe Adress is:"+mydeviceadress;
Toast.makeText(this, Status, Toast.LENGTH_LONG).show();
}
else
{
Intent enableBtIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_ENABLE);
startActivityForResult(enableBtIntent, REQ_BT_ENABLE);
Toast.makeText(this, "Enabling Bluetooth!!", Toast.LENGTH_LONG).show();
}
/*
* Getting paired devices and saving them on an ArrayAdapter
* */
pairedDevices = mBluetoothAdapter.getBondedDevices();
// If there are paired devices
if (pairedDevices.size() > 0) {
// Loop through paired devices
for (BluetoothDevice device : pairedDevices) {
// Add the name and address to an array adapter to show in a ListView
mArrayAdapter.add(device.getName() + "\n" + device.getAddress());
}
}
/*Create a BroadcastReceiver for ACTION_FOUND
*
* */
final BroadcastReceiver Receiver = new BroadcastReceiver() {
public void onReceive(Context context, Intent intent) {
String action = intent.getAction();
// When discovery finds a device
if (BluetoothDevice.ACTION_FOUND.equals(action)) {
// Get the BluetoothDevice object from the Intent
BluetoothDevice device = intent.getParcelableExtra(BluetoothDevice.EXTRA_DEVICE);
// Add the name and address to an array adapter to show in a ListView
mArrayAdapter.add(device.getName() + "\n" + device.getAddress());
}
}
};
// Register the BroadcastReceiver
IntentFilter filter = new IntentFilter(BluetoothDevice.ACTION_FOUND);
registerReceiver(Receiver, filter);
/*
* to make the device discoverable
* */
Intent discoverableIntent = new Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(discoverableIntent);
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.bluetooth, menu);
return true;
}
}
LogCat 消息：
> 04-04 16:41:58.051: E/BluetoothAdapter(1082): Bluetooth binder is null
> 04-04 16:41:58.111: D/AndroidRuntime(1082): Shutting down VM 04-04
> 16:41:58.111: W/dalvikvm(1082): threadid=1: thread exiting with
> uncaught exception (group=0x40a71930) 04-04 16:41:58.131:
> E/AndroidRuntime(1082): FATAL EXCEPTION: main 04-04 16:41:58.131:
> E/AndroidRuntime(1082): java.lang.RuntimeException: Unable to start
> activity
>
ComponentInfo{com.example.adil_bluetooth_1st/com.example.adil_bluetooth_1st.Bluetooth}:
> java.lang.NullPointerException 04-04 16:41:58.131:
> E/AndroidRuntime(1082): at
> android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
> 04-04 16:41:58.131: E/AndroidRuntime(1082): at
> android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
> 04-04 16:41:58.131: E/AndroidRuntime(1082): at
> android.app.ActivityThread.access$600(ActivityThread.java:141) 04-04
> 16:41:58.131: E/AndroidRuntime(1082): at
> android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
> 04-04 16:41:58.131: E/AndroidRuntime(1082): at
> android.os.Handler.dispatchMessage(Handler.java:99) 04-04
> 16:41:58.131: E/AndroidRuntime(1082): at
> android.os.Looper.loop(Looper.java:137) 04-04 16:41:58.131:
> E/AndroidRuntime(1082): at
> android.app.ActivityThread.main(ActivityThread.java:5041) 04-04
> 16:41:58.131: E/AndroidRuntime(1082): at
> java.lang.reflect.Method.invokeNative(Native Method) 04-04
> 16:41:58.131: E/AndroidRuntime(1082): at
> java.lang.reflect.Method.invoke(Method.java:511) 04-04 16:41:58.131:
> E/AndroidRuntime(1082): at
> com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
> 04-04 16:41:58.131: E/AndroidRuntime(1082): at
> com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 04-04
> 16:41:58.131: E/AndroidRuntime(1082): at
> dalvik.system.NativeStart.main(Native Method) 04-04 16:41:58.131:
> E/AndroidRuntime(1082): Caused by: java.lang.NullPointerException
> 04-04 16:41:58.131: E/AndroidRuntime(1082): at
> com.example.adil_bluetooth_1st.Bluetooth.onCreate(Bluetooth.java:38)
> 04-04 16:41:58.131: E/AndroidRuntime(1082): at
> android.app.Activity.performCreate(Activity.java:5104) 04-04
> 16:41:58.131: E/AndroidRuntime(1082): at
> android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
> 04-04 16:41:58.131: E/AndroidRuntime(1082): at
> android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
> 04-04 16:41:58.131: E/AndroidRuntime(1082): ... 11 more