应用程序崩溃时,关闭/重启然后pressing按钮 [英] app crashes when closing / reopening then pressing button
问题描述
我运行Eclipse和诚实自学的Android编程的基础知识。我想我会从一个简单的手电筒的应用程序,这样我可以得到一个更好地了解如何工作的。该应用程序本身工作正常,并启动相机闪光灯。
我的问题是,当我preSS主页按钮,然后返回到应用程序和preSS按钮,打开手电筒,应用程序崩溃。我一直在阅读了很多,我猜我没有一个onResume这是因为,但我可能是错的。任何帮助是极大的AP preciated。
进口android.app.Activity;
进口android.content.Context;
进口android.content.pm.PackageManager;
进口android.hardware.Camera;
进口android.hardware.Camera.Parameters;
进口android.os.Bundle;
进口android.util.Log;
进口android.view.View;
进口android.view.View.OnClickListener;
进口android.widget.Button;
进口com.pmm.lettherebe.R; 公共类MainActivity延伸活动{//标志检测闪光灯开启或关闭
私人布尔isLighOn = FALSE;私人相机拍照;私人Button按钮;@覆盖
保护无效的onPause(){
super.onPause(); 如果(相机!= NULL){
camera.release();;
}
}
@覆盖
公共无效的onCreate(捆绑savedInstanceState){
super.onCreate(savedInstanceState);
的setContentView(R.layout.activity_main); 按钮=(按钮)findViewById(R.id.buttonFlashlight); 上下文的背景下=这;
软件包管理系统下午= context.getPackageManager(); //如果设备支持相机?
如果(!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA)){
Log.e(犯错,设备没有摄像头!);
返回;
} 相机= Camera.open();
最终的参数P = camera.getParameters(); button.setOnClickListener(新OnClickListener(){ @覆盖
公共无效的onClick(查看为arg0){ 如果(isLighOn){
Log.i(信息,火炬被关闭!); p.setFlashMode(Parameters.FLASH_MODE_OFF);
camera.setParameters(P);
camera.stop preVIEW();
isLighOn = FALSE;
}其他{ Log.i(信息,火炬被打开!);
p.setFlashMode(Parameters.FLASH_MODE_TORCH); camera.setParameters(P);
camera.start preVIEW();
isLighOn =真; } }
});}
}
下面是logcat的错误:
20 07-02:32:19.680:D / OpenGLRenderer(14897):启用调试模式0
07-02 20:32:21.121:I /信息(14897):火炬是开启!
07-02 20:32:22.553:I /信息(14897):火炬是关闭!
07-02 20:32:23.363:I /信息(14897):火炬是开启!
07-02 20:32:23.964:I /信息(14897):火炬是关闭!
07-02 20:32:29.090:I /信息(14897):火炬是开启!
07-02 20:32:29.090:D / AndroidRuntime(14897):关闭VM
07-02 20:32:29.090:W / dalvikvm(14897):主题ID = 1:螺纹退出
withuncaught异常(组= 0x41b46930)
07-02 20:32:29.090:E / AndroidRuntime(14897):致命异常:主要
07-02 20:32:29.090:E / AndroidRuntime(14897):了java.lang.RuntimeException:方法
释放后alled()
07-02 20:32:29.090:E / AndroidRuntime(14897):在
android.hardware.Camera.native_setParameters(本机方法)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
android.hardware.Camera.setParameters(Camera.java:1496)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
com.pmm.lettherebe.MainActivity $ 1.onClick(MainActivity.java:74)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
android.view.View.performClick(View.java:4204)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
android.view.View $ PerformClick.run(View.java:17355)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
android.os.Handler.handleCallback(Handler.java:725)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
android.os.Handler.dispatchMessage(Handler.java:92)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
android.os.Looper.loop(Looper.java:137)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
android.app.ActivityThread.main(ActivityThread.java:5195)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
java.lang.reflect.Method.invokeNative(本机方法)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
java.lang.reflect.Method.invoke(Method.java:511)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
com.android.internal.os.ZygoteInit $ MethodAndArgsCaller.run(ZygoteInit.java:795)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562)
07-02 20:32:29.090:E / AndroidRuntime(14897):在
dalvik.system.NativeStart.main(本机方法)
07-02 20:32:31.222:I /流程(14897):发送信号。 PID:14897 SIG:9
块引用>解决方案看来,
的onPause
您的活动被调用,而你释放相机 - 这是件好事。但是,你永远不会重新初始化。Android开发者指南有这个确切的例子。
基本上,你需要做的是这样的:
@覆盖
保护无效的onPause(){
super.onPause(); 如果(相机!= NULL){
camera.release();
摄像头= NULL;
}
}@覆盖
保护无效onResume(){
super.onResume(); 如果(相机== NULL){
initializeCamera();
}
}然后移动相机的所有初始化code从
的onCreate
进入一个新的initializeCamera
方法。请注意,你不应该在
的onCreate
初始化相机,因为它是在onResume
正在做(这被称为甚至在第一次加载)。I'm running eclipse and honestly teaching myself the basics of android programming. I'd figure I would start with a simple flashlight app just so I can get a better understanding of how this works. The app itself works fine and initiates the camera flash.
My problem is when I press the home button, then go back into the app and press the button to turn on the flashlight, the app crashes. I've been reading a lot and i'm guessing it's due to me not having an "onResume" but I may be wrong. Any help is greatly appreciated.
import android.app.Activity; import android.content.Context; import android.content.pm.PackageManager; import android.hardware.Camera; import android.hardware.Camera.Parameters; import android.os.Bundle; import android.util.Log; import android.view.View; import android.view.View.OnClickListener; import android.widget.Button; import com.pmm.lettherebe.R; public class MainActivity extends Activity { //flag to detect flash is on or off private boolean isLighOn = false; private Camera camera; private Button button; @Override protected void onPause() { super.onPause(); if (camera != null) { camera.release();; } } @Override public 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(); // if device support camera? if (!pm.hasSystemFeature(PackageManager.FEATURE_CAMERA)) { Log.e("err", "Device has no camera!"); return; } camera = Camera.open(); final Parameters p = camera.getParameters(); button.setOnClickListener(new OnClickListener() { @Override public void onClick(View arg0) { if (isLighOn) { Log.i("info", "torch is turn off!"); p.setFlashMode(Parameters.FLASH_MODE_OFF); camera.setParameters(p); camera.stopPreview(); isLighOn = false; } else { Log.i("info", "torch is turn on!"); p.setFlashMode(Parameters.FLASH_MODE_TORCH); camera.setParameters(p); camera.startPreview(); isLighOn = true; } } }); } }
Here is the logcat error:
07-02 20:32:19.680: D/OpenGLRenderer(14897): Enabling debug mode 0 07-02 20:32:21.121: I/info(14897): torch is turn on! 07-02 20:32:22.553: I/info(14897): torch is turn off! 07-02 20:32:23.363: I/info(14897): torch is turn on! 07-02 20:32:23.964: I/info(14897): torch is turn off! 07-02 20:32:29.090: I/info(14897): torch is turn on! 07-02 20:32:29.090: D/AndroidRuntime(14897): Shutting down VM 07-02 20:32:29.090: W/dalvikvm(14897): threadid=1: thread exiting withuncaught exception (group=0x41b46930) 07-02 20:32:29.090: E/AndroidRuntime(14897): FATAL EXCEPTION: main 07-02 20:32:29.090: E/AndroidRuntime(14897): java.lang.RuntimeException: Method alled after release() 07-02 20:32:29.090: E/AndroidRuntime(14897): at android.hardware.Camera.native_setParameters(Native Method) 07-02 20:32:29.090: E/AndroidRuntime(14897): at android.hardware.Camera.setParameters(Camera.java:1496) 07-02 20:32:29.090: E/AndroidRuntime(14897): at com.pmm.lettherebe.MainActivity$1.onClick(MainActivity.java:74) 07-02 20:32:29.090: E/AndroidRuntime(14897): at android.view.View.performClick(View.java:4204) 07-02 20:32:29.090: E/AndroidRuntime(14897): at android.view.View$PerformClick.run(View.java:17355) 07-02 20:32:29.090: E/AndroidRuntime(14897): at android.os.Handler.handleCallback(Handler.java:725) 07-02 20:32:29.090: E/AndroidRuntime(14897): at android.os.Handler.dispatchMessage(Handler.java:92) 07-02 20:32:29.090: E/AndroidRuntime(14897): at android.os.Looper.loop(Looper.java:137) 07-02 20:32:29.090: E/AndroidRuntime(14897): at android.app.ActivityThread.main(ActivityThread.java:5195) 07-02 20:32:29.090: E/AndroidRuntime(14897): at java.lang.reflect.Method.invokeNative(Native Method) 07-02 20:32:29.090: E/AndroidRuntime(14897): at java.lang.reflect.Method.invoke(Method.java:511) 07-02 20:32:29.090: E/AndroidRuntime(14897): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:795) 07-02 20:32:29.090: E/AndroidRuntime(14897): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:562) 07-02 20:32:29.090: E/AndroidRuntime(14897): at dalvik.system.NativeStart.main(Native Method) 07-02 20:32:31.222: I/Process(14897): Sending signal. PID: 14897 SIG: 9
解决方案It appears that the
onPause
in your activity is being called, and you're releasing the Camera - this is good. However, you never re-initialize it.The Android developer guide has this exact example.
Basically, you need to do something like this:
@Override protected void onPause() { super.onPause(); if (camera != null) { camera.release(); camera = null; } } @Override protected void onResume() { super.onResume(); if (camera == null) { initializeCamera(); } }
Then you move all the camera initialization code from your
onCreate
into a newinitializeCamera
method.Note you should not initialize the camera in
onCreate
, since it is being done inonResume
(which is called even on first load).这篇关于应用程序崩溃时,关闭/重启然后pressing按钮的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!