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我有一个计时器,它应该告诉我的应用程序是时候读取一些数据了
new Timer().schedule(new TimerTask() {
@Override
public void run() {
try {
states[PICK_FRAME_STATE]=true;
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}, 1000/fRate);
states 数组的 final boolean[]
绘制循环期间读取数据的位置
if(lastFrame!=null&&states[PICK_FRAME_STATE]){
father.image(lastFrame, 500, 200,VRes,HRes);
buff.add(lastFrame);
//states[PICK_FRAME_STATE]=false;
System.out.println(is++);
}
但是指令
状态[PICK_FRAME_STATE]=false
;
如果不加注释会导致应用程序崩溃。
我希望能够检测到循环中何时至少传递了 1000/fRate
毫秒,一般来说,它比 1000/fRate
更快。
我认为TimerTask
在每个时间间隔至少授予一次执行,但我在这个实现中遇到了并发问题(毫不奇怪),有什么解决方法吗?
java.lang.NullPointerException
at processing.opengl.Texture.copyBufferFromSource(Texture.java:859)
at sun.reflect.GeneratedMethodAccessor15.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at processing.video.Capture.read(Unknown Source)
at aaa.view.video.CameraWindow.draw(CameraWindow.java:78)
at aaa.view.video.CameraWindow.render(CameraWindow.java:99)
at aaa.desktop.view.ProfileView.render(ProfileView.java:55)
at aaa.desktop.view.MainView.draw(MainView.java:385)
at processing.core.PApplet.handleDraw(PApplet.java:2386)
at processing.opengl.PJOGL$PGLListener.display(PJOGL.java:862)
at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:665)
at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:649)
at javax.media.opengl.awt.GLCanvas$10.run(GLCanvas.java:1289)
at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:1119)
at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:994)
at javax.media.opengl.awt.GLCanvas$11.run(GLCanvas.java:1300)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:301)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
(编辑托比亚斯的回答)
long time=System.currentTimeMillis();
public void draw() {
if (video.available()) {
video.read(); // Read a new video frame
lastFrame=video;
}
if(lastFrame!=null && System.currentTimeMillis() - time >= 1000){
time = System.currentTimeMillis();
father.image(lastFrame, 500, 200,VRes,HRes);
buff.add(lastFrame);
System.out.println(is++);
}
}
工作很艰难,它像以前一样给出了 3 个异常,但之后一切都很好。奇怪的是,如果我评论该行
time = System.currentTimeMillis();
我也不异常(exception)
0 <=first frame added
java.lang.NullPointerException
at processing.opengl.Texture.copyBufferFromSource(Texture.java:859)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at processing.video.Capture.read(Unknown Source)
at ygg.view.video.CameraWindow.draw(CameraWindow.java:81)
at ygg.view.video.CameraWindow.render(CameraWindow.java:101)
at ygg.desktop.view.ProfileView.render(ProfileView.java:55)
at ygg.desktop.view.MainView.draw(MainView.java:385)
at processing.core.PApplet.handleDraw(PApplet.java:2386)
at processing.opengl.PJOGL$PGLListener.display(PJOGL.java:862)
at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:665)
at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:649)
at javax.media.opengl.awt.GLCanvas$10.run(GLCanvas.java:1289)
at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:1119)
at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:994)
at javax.media.opengl.awt.GLCanvas$11.run(GLCanvas.java:1300)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:301)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
java.lang.NullPointerException
at processing.opengl.Texture.copyBufferFromSource(Texture.java:859)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at processing.video.Capture.read(Unknown Source)
at ygg.view.video.CameraWindow.draw(CameraWindow.java:81)
at ygg.view.video.CameraWindow.render(CameraWindow.java:101)
at ygg.desktop.view.ProfileView.render(ProfileView.java:55)
at ygg.desktop.view.MainView.draw(MainView.java:385)
at processing.core.PApplet.handleDraw(PApplet.java:2386)
at processing.opengl.PJOGL$PGLListener.display(PJOGL.java:862)
at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:665)
at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:649)
at javax.media.opengl.awt.GLCanvas$10.run(GLCanvas.java:1289)
at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:1119)
at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:994)
at javax.media.opengl.awt.GLCanvas$11.run(GLCanvas.java:1300)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:301)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
java.lang.NullPointerException
at processing.opengl.Texture.copyBufferFromSource(Texture.java:859)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at processing.video.Capture.read(Unknown Source)
at ygg.view.video.CameraWindow.draw(CameraWindow.java:81)
at ygg.view.video.CameraWindow.render(CameraWindow.java:101)
at ygg.desktop.view.ProfileView.render(ProfileView.java:55)
at ygg.desktop.view.MainView.draw(MainView.java:385)
at processing.core.PApplet.handleDraw(PApplet.java:2386)
at processing.opengl.PJOGL$PGLListener.display(PJOGL.java:862)
at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:665)
at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:649)
at javax.media.opengl.awt.GLCanvas$10.run(GLCanvas.java:1289)
at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:1119)
at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:994)
at javax.media.opengl.awt.GLCanvas$11.run(GLCanvas.java:1300)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:301)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
java.lang.NullPointerException
at processing.opengl.Texture.copyBufferFromSource(Texture.java:859)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at processing.video.Capture.read(Unknown Source)
at ygg.view.video.CameraWindow.draw(CameraWindow.java:81)
at ygg.view.video.CameraWindow.render(CameraWindow.java:101)
at ygg.desktop.view.ProfileView.render(ProfileView.java:55)
at ygg.desktop.view.MainView.draw(MainView.java:385)
at processing.core.PApplet.handleDraw(PApplet.java:2386)
at processing.opengl.PJOGL$PGLListener.display(PJOGL.java:862)
at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:665)
at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:649)
at javax.media.opengl.awt.GLCanvas$10.run(GLCanvas.java:1289)
at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:1119)
at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:994)
at javax.media.opengl.awt.GLCanvas$11.run(GLCanvas.java:1300)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:301)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
java.lang.NullPointerException
at processing.opengl.Texture.copyBufferFromSource(Texture.java:859)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at processing.video.Capture.read(Unknown Source)
at ygg.view.video.CameraWindow.draw(CameraWindow.java:81)
at ygg.view.video.CameraWindow.render(CameraWindow.java:101)
at ygg.desktop.view.ProfileView.render(ProfileView.java:55)
at ygg.desktop.view.MainView.draw(MainView.java:385)
at processing.core.PApplet.handleDraw(PApplet.java:2386)
at processing.opengl.PJOGL$PGLListener.display(PJOGL.java:862)
at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:665)
at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:649)
at javax.media.opengl.awt.GLCanvas$10.run(GLCanvas.java:1289)
at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:1119)
at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:994)
at javax.media.opengl.awt.GLCanvas$11.run(GLCanvas.java:1300)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:301)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
java.lang.NullPointerException
at processing.opengl.Texture.copyBufferFromSource(Texture.java:859)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at processing.video.Capture.read(Unknown Source)
at ygg.view.video.CameraWindow.draw(CameraWindow.java:81)
at ygg.view.video.CameraWindow.render(CameraWindow.java:101)
at ygg.desktop.view.ProfileView.render(ProfileView.java:55)
at ygg.desktop.view.MainView.draw(MainView.java:385)
at processing.core.PApplet.handleDraw(PApplet.java:2386)
at processing.opengl.PJOGL$PGLListener.display(PJOGL.java:862)
at jogamp.opengl.GLDrawableHelper.displayImpl(GLDrawableHelper.java:665)
at jogamp.opengl.GLDrawableHelper.display(GLDrawableHelper.java:649)
at javax.media.opengl.awt.GLCanvas$10.run(GLCanvas.java:1289)
at jogamp.opengl.GLDrawableHelper.invokeGLImpl(GLDrawableHelper.java:1119)
at jogamp.opengl.GLDrawableHelper.invokeGL(GLDrawableHelper.java:994)
at javax.media.opengl.awt.GLCanvas$11.run(GLCanvas.java:1300)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:301)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:756)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:726)
at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)
1
2
3
ecc...每 1000 毫秒
最佳答案
试试这个
private long time = System.currentTimeMillis();
//...
// draw call:
if(lastFrame != null && System.currentTimeMillis() - time >= 1000){
// do stuff
time = System.currentTimeMillis();
}
//do stuff
最多每 1000 毫秒调用一次。没有任何 TimerTask 魔法。
尝试使用此方法捕获“丢失”的帧:
private long time = System.currentTimeMillis();
//...
// draw call:
long delta = System.currentTimeMillis() - time;
if(lastFrame != null && delta >= 1000){
int framesMissed = delta / 1000; // rounds to full seconds
for(int i=0;i<framesMissed;i++){
// do stuff for each missed frame/picture
}
// apply "overlap" so we actually carry the right result to the next call
time = System.currentTimeMillis() - (delta-(1000*framesMissed));
}
//do stuff
现在将在每一秒内被调用,忽略绘制调用的频率(它们可能比 1000 毫秒更快或更慢)
关于java - TimerTask并发问题,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/42296851/
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