firstgui.java

国外的数据结构与算法分析用书

import java.awt.*; // graphical classes
import java.awt.event.*; // event classes

/**	A class that contains two buttons and a text field.  When the buttons
	on the screen are clicked, the value in the text field changes accordingly. */
public class FirstGui extends Frame implements ActionListener
{
	Button countBtn, resetBtn;
	int counter = 0;
	TextField counterFld;

	public FirstGui()
	{
		super("First GUI"); // add title to window
		setLayout(new FlowLayout(FlowLayout.CENTER)); // how items will be laid out
		countBtn = new Button("Click Me!");
		resetBtn = new Button("Reset");
		counterFld = new TextField("0", 4);
		
		/*	Indicate who will handle events. */
		countBtn.addActionListener(this);
		resetBtn.addActionListener(this);
		addWindowListener(new WindowAdapter() // inner anonymous class
		{
			/*	Called when the user closes the window. */
			public void windowClosing(WindowEvent we)
			{
				setVisible(false); // hide the window
				System.exit(0); // finish program
			}
		});

		/*	Add components to display. */
		add(countBtn);
		add(counterFld);
		add(resetBtn);
		
		setSize(300, 100); // set dimensions of the window
		setVisible(true); // make window appear
	}

	/**	This method is what is called when the buttons are clicked. */ 
	public void actionPerformed(ActionEvent ae)
	{
		if(ae.getSource() == countBtn) // count button clicked
			counter++;
		else
			counter = 0;
		counterFld.setText(counter + ""); // update text field
	}

	/**	Starting point, just call the constructor. */
	public static void main(String[] args)
	{
		new FirstGui();
	}
}