onscreen keyboard

i want to make 开发者_JS百科a onscreen keyboard in java but the problem is when the focus is lost how can we send the keystroke on another application through my java proogram

It would depend on the platform of your hardware and the target application. For example, if you are writing a Java program that sends key strokes to a Windows application, you could probably use Windows messages via JNI. For native applications on devices like mobile phones, you might have to go down to lower level API of the device.