ch7_e7_22.java

各种关于JAVA的初级编程

import java.applet.*;
import java.awt.*; 
import java.awt.event.*;

public class ch7_e7_22 extends Applet implements ItemListener
{
    Checkbox ckb = new Checkbox("背景色");
    CheckboxGroup style = new CheckboxGroup();
    Checkbox p = new Checkbox("普通",true,style);
    Checkbox b = new Checkbox("黑体",false,style);
    Checkbox i = new Checkbox("斜体",false,style);
    Choice size = new Choice();

    MyCanvas myCanvas = new MyCanvas();

    public void init()
    {
        add(ckb);
        add(p);
        add(b);
        add(i);
        size.add("10");
        size.add("14");
        size.add("18");
        add(size);
        
        add(myCanvas);
        //myCanvas.setVisible(true);
        //myCanvas.requestFocus();
        myCanvas.setSize(new Dimension(400,200));
        
        p.addItemListener(this);
        b.addItemListener(this);
        i.addItemListener(this);
        ckb.addItemListener(this);
        size.addItemListener(this);
    }
    public void itemStateChanged(ItemEvent e)
    {
        Checkbox temp;
        Font oldF = myCanvas.getFont();
        String s;
        int si;

        if(e.getItemSelectable() instanceof Checkbox)
        {
            temp = (Checkbox)(e.getItemSelectable());
            if(temp.getLabel()=="背景色")
                if(temp.getState())
                    myCanvas.setBackground(Color.cyan);
                else
                    myCanvas.setBackground(Color.gray);
            else if(temp.getLabel()=="普通" && temp.getState())
                myCanvas.setFont(new Font(oldF.getName(),Font.PLAIN,oldF.getSize()));
            else if(temp.getLabel()=="黑体" && temp.getState())
                myCanvas.setFont(new Font(oldF.getName(),Font.BOLD,oldF.getSize()));
            else if(temp.getLabel()=="斜体" && temp.getState())
                myCanvas.setFont(new Font(oldF.getName(),Font.ITALIC,oldF.getSize()));
            repaint();
        }
        else if(e.getItemSelectable() instanceof Choice)
        {
            Choice ctemp = (Choice)(e.getItemSelectable());
            s = ctemp.getSelectedItem();
            si = Integer.parseInt(s);
            myCanvas.setFont(new Font(oldF.getName(),oldF.getStyle(),si));
            repaint();
        }
    }
}

class MyCanvas extends Canvas
{
    public void paint(Graphics g)
    {
        g.drawString("SEE WHAT'S CHANGING?", 10, 40);
    }
}