stockmanager.java

手机程序股票购买售出的例子

//StockManager.java

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import java.io.IOException;
import java.util.*;

public class StockManager extends MIDlet implements Controller
{
	private RMSStockStore _rmsgs = null;
	private Display _display = null;
	private Stack _screenStack = null;

    public StockManager()
    {
		_rmsgs = new RMSStockStore();
		_screenStack = new Stack();

		nextScreen( new WelcomeScreen( (Controller) this) );
	}

    public void startApp()
    {
    }

    /**
     * Pause is a no-op since there are no background activities or
     * record stores that need to be closed.
     */
    public void pauseApp() {}

    /**
     * Destroy must cleanup everything not handled by the garbage collector.
     * In this case there is nothing to cleanup.
     */
    public void destroyApp(boolean unconditional) {}

	private Display getDisplay()
	{
		if ( _display == null)
		{
			_display = Display.getDisplay(this);
		}

		return _display;
	}

	// for interface controller
	public StockDatabase getStockDatabase()
	{
		return (StockDatabase) _rmsgs;
	}

	public Displayable currentScreen()
	{
		return getDisplay().getCurrent();
	}

	public void nextScreen(Displayable display)
	{
		Displayable currentScreen = getDisplay().getCurrent();

		if ( currentScreen != null)
		{
			_screenStack.push( currentScreen );
		}

		getDisplay().setCurrent( display);
	}

	public void lastScreen()
	{
		Displayable display = null;

		if ( !_screenStack.empty() )
		{
			display = (Displayable) _screenStack.pop();
		}
		else
		{
			display = new WelcomeScreen( (Controller) this );
		}

		getDisplay().setCurrent( display);
	}

	private void printStack(String message, Stack stack)
	{
		Enumeration elements = stack.elements();

		System.out.println(message);
		String subMessage = message.substring(0,2);

		while ( elements.hasMoreElements() )
		{
			System.out.println("\t"+ subMessage +":"+ elements.nextElement().toString() );
		}
	}
}