获取蓝牙状态报错，请问是怎么回事啊

xiaonaihe 2014-03-09 07:01:29

<uses-permission android:name="android.permission.BLUETOOTH" />
<uses-permission android:name="android.permission.BLUETOOTH_ADMIN" />
已经加入权限获取，看错误信息好像是if (mBluetoothAdapter.getState()==BluetoothAdapter.STATE_ON)这一行错误。把if语句整个去掉发现下面的mBluetoothAdapter.enable();也会报错



Switch switch2;

BluetoothAdapter mBluetoothAdapter;

switch2=(Switch)findViewById(R.id.switch2);

mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();

		

		if (mBluetoothAdapter.getState()==BluetoothAdapter.STATE_ON){

			switch2.setChecked(true);

		} else {

			switch2.setChecked(false);



		}

		switch2.setOnCheckedChangeListener(new OnCheckedChangeListener() {



			@Override

			public void onCheckedChanged(CompoundButton buttonView,

					boolean isChecked) {

				// TODO Auto-generated method stub

				if (isChecked) {

					mBluetoothAdapter.enable();



					Toast.makeText(EnergySaving.this,

							"当前蓝牙状态为1" + mBluetoothAdapter.getState(),

							Toast.LENGTH_SHORT).show();



				} else {

					mBluetoothAdapter.disable();



					Toast.makeText(EnergySaving.this,

							"当前蓝牙状态为2" + mBluetoothAdapter.getState(),

							Toast.LENGTH_SHORT).show();

				}

			}

		});

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xiaonaihe 2014-03-31

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空指针是应为虚拟机没有蓝牙，无法获取到BluetoothAdapter.getDefaultAdapter();到真机上测试正常。

xiaonaihe 2014-03-11

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import android.annotation.SuppressLint;
import android.app.Activity;
import android.bluetooth.BluetoothAdapter;
import android.content.BroadcastReceiver;
import android.content.ContentResolver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.net.Uri;
import android.net.wifi.WifiManager;
import android.os.BatteryManager;
import android.os.Bundle;
import android.provider.Settings;
import android.provider.Settings.SettingNotFoundException;
import android.view.View;
import android.view.WindowManager;
import android.widget.CheckBox;
import android.widget.CompoundButton;
import android.widget.CompoundButton.OnCheckedChangeListener;
import android.widget.ImageView;
import android.widget.SeekBar;
import android.widget.SeekBar.OnSeekBarChangeListener;
import android.widget.Switch;
import android.widget.TextView;
import android.widget.Toast;

@SuppressLint("NewApi")
public class EnergySaving extends Activity {

	private int level;
	private int status;
	ImageView imageView1;
	TextView textView1;
	TextView textView3;
	CheckBox checkBox1;
	private SeekBar seekBar;
	Switch switch1;
	Switch switch2;
	WifiManager wifiManager;
	BluetoothAdapter mBluetoothAdapter;
	

	@Override
	protected void onCreate(Bundle savedInstanceState) {
		// TODO Auto-generated method stub
		super.onCreate(savedInstanceState);
		setContentView(R.layout.energysaving);
		this.setTitle("节能控制");
		registerReceiver(batteryChangedReceiver, new IntentFilter(
				Intent.ACTION_BATTERY_CHANGED));
		imageView1 = (ImageView) findViewById(R.id.imageView1);
		textView1 = (TextView) findViewById(R.id.textView1);
		textView3 = (TextView) findViewById(R.id.textView3);

		textView1.setTextSize(22);

		seekBar = (SeekBar) findViewById(R.id.seekBar1);
		seekBar.setMax(255);// 最大亮度为255，设定进度条的max为255
		int nowBrightnessValue = 0;
		ContentResolver resolver = this.getContentResolver();
		try {
			nowBrightnessValue = android.provider.Settings.System.getInt(
					resolver, Settings.System.SCREEN_BRIGHTNESS);
		} catch (SettingNotFoundException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		textView3.setText("当前屏幕亮度:" + nowBrightnessValue);
		seekBar.setProgress(nowBrightnessValue);// 先显示，后看是否手动还是自动调节亮度
		checkBox1 = (CheckBox) findViewById(R.id.checkBox1);
		checkBox1.setOnClickListener(new View.OnClickListener() {

			@Override
			public void onClick(View v) {
				// TODO Auto-generated method stub
				if (checkBox1.isChecked()) {
					Settings.System.putInt(getContentResolver(),
							Settings.System.SCREEN_BRIGHTNESS_MODE,
							Settings.System.SCREEN_BRIGHTNESS_MODE_MANUAL);// 关闭自动调节
					seekBar.setEnabled(true);
				} else {

					Settings.System.putInt(getContentResolver(),
							Settings.System.SCREEN_BRIGHTNESS_MODE,
							Settings.System.SCREEN_BRIGHTNESS_MODE_AUTOMATIC);// 未选中手动调节，则改为自动调节亮度
					seekBar.setEnabled(false);

				}
			}
		});
		seekBar.setOnSeekBarChangeListener(new SeekBarChangeListenerImp());
		switch1 = (Switch) findViewById(R.id.switch1);
		wifiManager = (WifiManager) this.getSystemService(Context.WIFI_SERVICE);

		if (wifiManager.getWifiState() == WifiManager.WIFI_STATE_ENABLED) {
			switch1.setChecked(true);
		} else {
			switch1.setChecked(false);

		}
		switch1.setOnCheckedChangeListener(new OnCheckedChangeListener() {

			@Override
			public void onCheckedChanged(CompoundButton buttonView,
					boolean isChecked) {
				// TODO Auto-generated method stub
				if (isChecked) {
					wifiManager.setWifiEnabled(true);

					Toast.makeText(EnergySaving.this,
							"当前Wifi网卡状态为1" + wifiManager.getWifiState(),
							Toast.LENGTH_SHORT).show();

				} else {
					wifiManager.setWifiEnabled(false);

					Toast.makeText(EnergySaving.this,
							"当前Wifi网卡状态为2" + wifiManager.getWifiState(),
							Toast.LENGTH_SHORT).show();
				}
			}
		});
		switch2=(Switch)findViewById(R.id.switch2);
		mBluetoothAdapter = BluetoothAdapter.getDefaultAdapter();
		
		if (mBluetoothAdapter.getState()==BluetoothAdapter.STATE_ON){
			switch2.setChecked(true);
		} else {
			switch2.setChecked(false);

		}
		switch2.setOnCheckedChangeListener(new OnCheckedChangeListener() {

			@Override
			public void onCheckedChanged(CompoundButton buttonView,
					boolean isChecked) {
				// TODO Auto-generated method stub
				if (isChecked) {
					mBluetoothAdapter.enable();

					Toast.makeText(EnergySaving.this,
							"当前蓝牙状态为1" + mBluetoothAdapter.getState(),
							Toast.LENGTH_SHORT).show();

				} else {
					mBluetoothAdapter.disable();

					Toast.makeText(EnergySaving.this,
							"当前蓝牙状态为2" + mBluetoothAdapter.getState(),
							Toast.LENGTH_SHORT).show();
				}
			}
		});

	}

	class SeekBarChangeListenerImp implements OnSeekBarChangeListener {

		public void onProgressChanged(SeekBar seekBar, int progress,
				boolean fromUser) {
			// TODO Auto-generated method stub

			setScreenBrightness(seekBar.getProgress());// 传入当前亮度

		}

		public void onStartTrackingTouch(SeekBar seekBar) {
			// TODO Auto-generated method stub
		}

		public void onStopTrackingTouch(SeekBar seekBar) {
			// TODO Auto-generated method stub
		}
	}

	// 设置屏幕亮度的函数

	public void setScreenBrightness(int num) {
		// TODO Auto-generated method stub
		ContentResolver resolver = this.getContentResolver();

		WindowManager.LayoutParams layoutParams = super.getWindow()
				.getAttributes();
		layoutParams.screenBrightness = (float) num / 255;// 设置屏幕的亮度
															// 要0~1，所以除以255
		super.getWindow().setAttributes(layoutParams);
		layoutParams = getWindow().getAttributes();
		textView3.setText("当前屏幕亮度:"
				+ String.valueOf(layoutParams.screenBrightness * 255)); // 显示0~255而不是0~1
		// 以下 几行保存亮度，即使退出app也是当前亮度
		Uri uri = android.provider.Settings.System
				.getUriFor("screen_brightness");

		android.provider.Settings.System.putInt(resolver, "screen_brightness",
				num);

		resolver.notifyChange(uri, null);
	}

	private BroadcastReceiver batteryChangedReceiver = new BroadcastReceiver() {

		public void onReceive(Context context, Intent intent) {
			if (Intent.ACTION_BATTERY_CHANGED.equals(intent.getAction())) {
				level = intent.getIntExtra("level", 0);
				int scale = intent.getIntExtra("scale", 100);
				status = intent.getIntExtra("status", 0);

				setBatteryInfo();
			}
		}
	};

	protected void setBatteryInfo() {
		// TODO Auto-generated method stub
		// 动态改变电量图片
		int resID = getResources().getIdentifier("stat_sys_battery_" + level,
				"drawable", "com.example.energysavingofmobilephone");
		imageView1.setImageResource(resID);
		if (status == BatteryManager.BATTERY_STATUS_CHARGING) {
			textView1.setTextColor(android.graphics.Color.BLUE);
			textView1.setText("充电中");
		} else {
			textView1.setTextColor(android.graphics.Color.GREEN);
			textView1.setText("未连接电源");

		}

	}

}

xiaonaihe 2014-03-11

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引用 4 楼 ultrapro 的回复:

manifest文件中声明这个activity了么

声明了，就做了这个新的功能的时候才出错了。我把完整贴出来

阿布1991 2014-03-11

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无法启动该activity，空指针的错误，明显不是这段代码的原因么

儿大不由爷 2014-03-11

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manifest文件中声明这个activity了么

xiaonaihe 2014-03-11

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新人求回答下。卡了好几天了

xiaonaihe 2014-03-10

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请问有谁能解答下么，谢谢啦

xiaonaihe 2014-03-09

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以下是错误提示 03-09 11:03:57.831: D/dalvikvm(1266): GC_CONCURRENT freed 62K, 7% free 2764K/2968K, paused 21ms+4ms, total 83ms 03-09 11:03:57.831: D/dalvikvm(1266): WAIT_FOR_CONCURRENT_GC blocked 17ms 03-09 11:03:57.861: I/dalvikvm-heap(1266): Grow heap (frag case) to 5.835MB for 3145744-byte allocation 03-09 11:03:57.981: D/dalvikvm(1266): GC_FOR_ALLOC freed 2K, 4% free 5833K/6044K, paused 113ms, total 114ms 03-09 11:03:58.051: D/dalvikvm(1266): GC_CONCURRENT freed <1K, 4% free 5833K/6044K, paused 9ms+17ms, total 76ms 03-09 11:03:58.571: I/Choreographer(1266): Skipped 97 frames! The application may be doing too much work on its main thread. 03-09 11:03:58.591: D/gralloc_goldfish(1266): Emulator without GPU emulation detected. 03-09 11:04:04.741: E/BluetoothAdapter(1266): Bluetooth binder is null 03-09 11:04:04.741: D/AndroidRuntime(1266): Shutting down VM 03-09 11:04:04.761: W/dalvikvm(1266): threadid=1: thread exiting with uncaught exception (group=0x40a71930) 03-09 11:04:04.861: E/AndroidRuntime(1266): FATAL EXCEPTION: main 03-09 11:04:04.861: E/AndroidRuntime(1266): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.energysavingofmobilephone/com.example.energysavingofmobilephone.EnergySaving}: java.lang.NullPointerException 03-09 11:04:04.861: E/AndroidRuntime(1266): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180) 03-09 11:04:04.861: E/AndroidRuntime(1266): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230) 03-09 11:04:04.861: E/AndroidRuntime(1266): at android.app.ActivityThread.access$600(ActivityThread.java:141) 03-09 11:04:04.861: E/AndroidRuntime(1266): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234) 03-09 11:04:04.861: E/AndroidRuntime(1266): at android.os.Handler.dispatchMessage(Handler.java:99) 03-09 11:04:04.861: E/AndroidRuntime(1266): at android.os.Looper.loop(Looper.java:137) 03-09 11:04:04.861: E/AndroidRuntime(1266): at android.app.ActivityThread.main(ActivityThread.java:5041) 03-09 11:04:04.861: E/AndroidRuntime(1266): at java.lang.reflect.Method.invokeNative(Native Method) 03-09 11:04:04.861: E/AndroidRuntime(1266): at java.lang.reflect.Method.invoke(Method.java:511) 03-09 11:04:04.861: E/AndroidRuntime(1266): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793) 03-09 11:04:04.861: E/AndroidRuntime(1266): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560) 03-09 11:04:04.861: E/AndroidRuntime(1266): at dalvik.system.NativeStart.main(Native Method) 03-09 11:04:04.861: E/AndroidRuntime(1266): Caused by: java.lang.NullPointerException 03-09 11:04:04.861: E/AndroidRuntime(1266): at com.example.energysavingofmobilephone.EnergySaving.onCreate(EnergySaving.java:132) 03-09 11:04:04.861: E/AndroidRuntime(1266): at android.app.Activity.performCreate(Activity.java:5104) 03-09 11:04:04.861: E/AndroidRuntime(1266): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080) 03-09 11:04:04.861: E/AndroidRuntime(1266): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144) 03-09 11:04:04.861: E/AndroidRuntime(1266): ... 11 more 03-09 11:04:07.001: I/Process(1266): Sending signal. PID: 1266 SIG: 9

Cancelling connection for unused peripheral , Did you forget to keep a reference to it?

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