问如何在Eclipse插件开发中禁用/启用视图工具栏菜单/操作

EN

Public class StartAction extends Action {

@Override
public void run() {
    //actual code run here
}

@Override
public boolean isEnabled() {
    //This is the initial value, Check for your respective criteria and return the appropriate value.
    return false;
}

@Override
public String getText() {
    return "Play";
}
}

Public class Playerview extends ViewPart
    {

 @Override
public void createPartControl(Composite parent) {

 //your player UI code here.


    //Listener registration. This is very important for enabling and disabling the tool bar level buttons
     addListenerObject(this);


    //Attach selection changed listener to the object where you want to perform the action based on the selection type. ex; viewer
    viewer.addselectionchanged(new SelectionChangedListener())  



      }
        }

    //selection changed

    private class SelectionChangedListener implements ISelectionChangedListener        {

    @Override
    public void selectionChanged(SelectionChangedEvent event) {
        ISelection selection = Viewer.getSelection();
        if (selection != null && selection instanceof StructuredSelection) {
            Object firstElement = ((StructuredSelection)selection).getFirstElement();

            //here you can handle the enable or disable based on your selection. that could be your viewer selection or toolbar.
            if (playaction.isEnabled()) { //once clicked on play, stop  should be enabled.
                stopaction.setEnabled(true); //Do required actions here.
                playaction.setEnabled (false);  //do

            }

        }

    }

    }