我正在尝试在手机和蓝牙设备之间建立蓝牙连接，但应用程序一直在崩溃。通过评论，我发现错误在openBT（）函数中。有人可以帮帮我吗？
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.Set;
import java.util.UUID;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.bluetooth.BluetoothDevice;
import android.bluetooth.BluetoothSocket;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
public class PageOne extends Activity {
TextView myLabel;
TextView deviceFound;
Button openButton,closeButton;
BluetoothAdapter mBluetoothAdapter;
BluetoothDevice mmDevice;
BluetoothSocket mmSocket;
OutputStream mmOutputStream;
InputStream mmInputStream;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.pageone);
mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
setUp();
openButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (openButton.getText().equals("Enable")) {
findBT();
}
if(openButton.getText().equals("Start Connection")){
System.out.println("here");
try{
openBT();
}catch (IOException e){e.printStackTrace();};
}
}
});
closeButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
closeBT();
System.out.println("here too");
}
});
}
private void setUp() {
openButton = (Button) findViewById(R.id.button1);
myLabel = (TextView) findViewById(R.id.textView1);
closeButton = (Button) findViewById(R.id.button2);
deviceFound = (TextView) findViewById(R.id.textView2);
setButtonText();
BroadcastReceiver receiver = new BroadcastReceiver() {
@Override
public void onReceive(Context context, Intent intent) {
setButtonText();
}
};
IntentFilter filter = new IntentFilter (BluetoothAdapter.ACTION_STATE_CHANGED);
registerReceiver (receiver, filter);
}
private void setButtonText() {
closeButton.setText("Disable bluetooth");
if (mBluetoothAdapter.isEnabled()) {
openButton.setText("Start Connection");
myLabel.setText("Bluetooth is enabled");
} else {
openButton.setText("Enable");
myLabel.setText("Bluetooth is disabled");
}
}
private void findBT(){
if(mBluetoothAdapter == null)
{
myLabel.setText("No bluetooth adapter available");
}
if (!mBluetoothAdapter.isEnabled()) {
Intent discoverableIntent = new
Intent(BluetoothAdapter.ACTION_REQUEST_DISCOVERABLE);
discoverableIntent.putExtra(BluetoothAdapter.EXTRA_DISCOVERABLE_DURATION, 300);
startActivity(discoverableIntent);
}
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
if(pairedDevices.size() > 0)
{
for(BluetoothDevice device : pairedDevices)
{
if(device.getName().equals("Hauwa"))
{
mmDevice = device;
break;
}
}
}
deviceFound.setText("Bluetooth Device Found");
}
private void closeBT(){
if (mBluetoothAdapter.isEnabled()) {
mBluetoothAdapter.disable();
deviceFound.setText("bvnbvnvb");
}
}
void openBT() throws IOException{
final UUID uuid = UUID.fromString("00001101-0000-1000-8000-00805f9b34fb");
mmSocket = mmDevice.createRfcommSocketToServiceRecord(uuid);
mmSocket.connect();
mmOutputStream = mmSocket.getOutputStream();
mmInputStream = mmSocket.getInputStream();
}
}
这是logcat错误
01-07 02:55:23.189: W/dalvikvm(11382): threadid=1: thread exiting with uncaught exception (group=0x401f0560)
01-07 02:55:23.189: E/AndroidRuntime(11382): FATAL EXCEPTION: main
01-07 02:55:23.189: E/AndroidRuntime(11382): java.lang.NullPointerException
01-07 02:55:23.189: E/AndroidRuntime(11382): at com.example.BluetoothExample.PageOne.openBT(PageOne.java:147)
01-07 02:55:23.189: E/AndroidRuntime(11382): at com.example.BluetoothExample.PageOne$1.onClick(PageOne.java:51)
01-07 02:55:23.189: E/AndroidRuntime(11382): at android.view.View.performClick(View.java:2579)
01-07 02:55:23.189: E/AndroidRuntime(11382): at android.view.View$PerformClick.run(View.java:9246)
01-07 02:55:23.189: E/AndroidRuntime(11382): at android.os.Handler.handleCallback(Handler.java:587)
01-07 02:55:23.189: E/AndroidRuntime(11382): at android.os.Handler.dispatchMessage(Handler.java:92)
01-07 02:55:23.189: E/AndroidRuntime(11382): at android.os.Looper.loop(Looper.java:130)
01-07 02:55:23.189: E/AndroidRuntime(11382): at android.app.ActivityThread.main(ActivityThread.java:3735)
01-07 02:55:23.189: E/AndroidRuntime(11382): at java.lang.reflect.Method.invokeNative(Native Method)
01-07 02:55:23.189: E/AndroidRuntime(11382): at java.lang.reflect.Method.invoke(Method.java:507)
01-07 02:55:23.189: E/AndroidRuntime(11382): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
01-07 02:55:23.189: E/AndroidRuntime(11382): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:662)
01-07 02:55:23.189: E/AndroidRuntime(11382): at dalvik.system.NativeStart.main(Native Method)
01-07 02:55:23.199: E/AndroidRuntime(11382): [Blue Error Handler] Make Debugging Report file for main
01-07 02:55:23.199: E/AndroidRuntime(11382): java.lang.NullPointerException
01-07 02:55:23.199: E/AndroidRuntime(11382): at com.example.BluetoothExample.PageOne.openBT(PageOne.java:147)
01-07 02:55:23.199: E/AndroidRuntime(11382): at com.example.BluetoothExample.PageOne$1.onClick(PageOne.java:51)
01-07 02:55:23.199: E/AndroidRuntime(11382): at android.view.View.performClick(View.java:2579)
01-07 02:55:23.199: E/AndroidRuntime(11382): at android.view.View$PerformClick.run(View.java:9246)
01-07 02:55:23.199: E/AndroidRuntime(11382): at android.os.Handler.handleCallback(Handler.java:587)
01-07 02:55:23.199: E/AndroidRuntime(11382): at android.os.Handler.dispatchMessage(Handler.java:92)
01-07 02:55:23.199: E/AndroidRuntime(11382): at android.os.Looper.loop(Looper.java:130)
01-07 02:55:23.199: E/AndroidRuntime(11382): at android.app.ActivityThread.main(ActivityThread.java:3735)
01-07 02:55:23.199: E/AndroidRuntime(11382): at java.lang.reflect.Method.invokeNative(Native Method)
01-07 02:55:23.199: E/AndroidRuntime(11382): at java.lang.reflect.Method.invoke(Method.java:507)
01-07 02:55:23.199: E/AndroidRuntime(11382): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:904)
01-07 02:55:23.199: E/AndroidRuntime(11382): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:662)
01-07 02:55:23.199: E/AndroidRuntime(11382): at dalvik.system.NativeStart.main(Native Method)
答案 0 :(得分：0)
你确定mmDevice不是空的吗？您确定在findBT()中设置了mmDevice吗？
Set<BluetoothDevice> pairedDevices = mBluetoothAdapter.getBondedDevices();
if(pairedDevices.size() > 0)
{
for(BluetoothDevice device : pairedDevices)
{
if(device.getName().equals("Hauwa"))
{
mmDevice = device;
break;
}
}
}
答案 1 :(得分：0)
<div class="container header-buffer">...</div>您需要防止设备名称为空。即使您自己的设备名称不为null，代码也可以读取附近的其他BLE设备为null。您还需要防止子字符串和equals函数溢出