Android中的Flashlight App每次都会崩溃

Question

首先，我决定开发一个手电筒应用程序作为我的第一个应用程序。但当我在有闪光灯的Galaxy S5上启动它时，它会强制关闭，但在没有闪光灯的Galaxy Y上，它会打开，按钮也会正常工作。即使它显示了日志中的更改！请帮帮忙。这是我的火炬开/关代码。

private boolean isFlashOn = false;
private Camera camera;
private Button button;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    button = (Button) findViewById(R.id.buttonFlashlight);
    Context context = this;
    PackageManager pm = context.getPackageManager();

    camera = Camera.open();
    final Camera.Parameters p = camera.getParameters();

    button.setOnClickListener(new View.OnClickListener() {
        public void onClick(View arg0) {
            if (isFlashOn) {
                Log.i("info", "torch is turned off!");
                p.setFlashMode(Camera.Parameters.FLASH_MODE_OFF);
                camera.setParameters(p);
                isFlashOn = false;
                button.setText("Torch-ON");
            } else {
                Log.i("info", "torch is turned on!");
                p.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
                camera.setParameters(p);
                isFlashOn = true;
                button.setText("Torch-OFF");
            }
        }
    });
}

@Override
protected void onStop() {
    super.onStop();
    if (camera != null) {
        camera.release();
    }
}

这里是logcat。

05-27 10:37:20.621  30404-30404/com.example.administrator.flashlight E/AndroidRuntime﹕ FATAL EXCEPTION: main
Process: com.example.administrator.flashlight, PID: 30404
java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.administrator.flashlight/com.example.administrator.flashlight.MainActivity}: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2658)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2723)
        at android.app.ActivityThread.access$900(ActivityThread.java:172)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1422)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:145)
        at android.app.ActivityThread.main(ActivityThread.java:5832)
        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:1388)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1183)
 Caused by: java.lang.IllegalStateException: You need to use a Theme.AppCompat theme (or descendant) with this activity.
        at android.support.v7.app.ActionBarActivityDelegate.onCreate(ActionBarActivityDelegate.java:151)
        at android.support.v7.app.ActionBarActivityDelegateBase.onCreate(ActionBarActivityDelegateBase.java:138)
        at android.support.v7.app.ActionBarActivity.onCreate(ActionBarActivity.java:123)
        at com.example.administrator.flashlight.MainActivity.onCreate(MainActivity.java:30)
        at android.app.Activity.performCreate(Activity.java:6221)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2611)
            at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2723)
            at android.app.ActivityThread.access$900(ActivityThread.java:172)
            at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1422)
            at android.os.Handler.dispatchMessage(Handler.java:102)
            at android.os.Looper.loop(Looper.java:145)
            at android.app.ActivityThread.main(ActivityThread.java:5832)
            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:1388)
            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1183)

Answer 1

类似这样的事情，首先使用开关打开，然后将条件设置为打开。再检查一下你的情况，(isFlashOn)这部分你在做什么。

p.setFlashMode(Camera.Parameters.FLASH_MODE_TORCH);
camera.setParameters(p);
isFlashOn = true;
button.setText("Torch-OFF");