staticcharmethods.java

金旭亮的java教案

// StaticCharMethods.java
// Demonstrates the static character testing methods
// and case conversion methods of class Character
// from the java.lang package.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;

public class StaticCharMethods extends JFrame {
   private char c;
   //以下定义几个图形界面组件
   private JLabel prompt;
   private JTextField input;
   private JTextArea outputArea;

   public StaticCharMethods()
   {
   	//super代表调用基类JFrame的构造方法，其结果是设置了窗口的标题栏
      super( "Static Character Methods" );

		//getContentPane是基类提供的方法，它获取窗体中可存放图形控件的空白区域
		//所有的可容纳其它图形控件的区域被称为----"容器",它有一个基类,称为Container
      Container container = getContentPane();
      //设置布局方式为流布局方式:即从左到右地放置控件,一行放不下,就移到下一行
      container.setLayout( new FlowLayout() );

      prompt =
         new JLabel( "Enter a character and press Enter" );
      container.add( prompt );  //将控件加入容器中

      input = new JTextField( 5 );
      //设定文本框对回车键响应
      input.addActionListener(
         new ActionListener() {
         	//在下面的函数中定义要干的事
            public void actionPerformed( ActionEvent e )
            {  
               String s = e.getActionCommand();
                              c = s.charAt( 0 );
               buildOutput();	//构造输出结果
            }
         }
      );
      container.add( input );

      outputArea = new JTextArea( 10, 20 );
      container.add( outputArea );

      setSize( 300, 250 );  // set the window size
      show();               // show the window
   }

   public void buildOutput()
   {
      outputArea.setText(
          "is defined: " + Character.isDefined( c ) +
          "\nis digit: " + Character.isDigit( c ) +	//是否数字
          "\nis Java letter: " +
          Character.isJavaIdentifierStart( c ) +	//是否可作为标识符的第一个字符
          "\nis Java letter or digit: " +
          Character.isJavaIdentifierPart( c ) +		//是否可作为标识符的字符
          "\nis letter: " + Character.isLetter( c ) +
          "\nis letter or digit: " +
          Character.isLetterOrDigit( c ) +
          "\nis lower case: " + Character.isLowerCase( c ) +
          "\nis upper case: " + Character.isUpperCase( c ) +
          "\nto upper case: " + Character.toUpperCase( c ) +
          "\nto lower case: " + Character.toLowerCase( c ) );
   }

	//程序入口点
   public static void main( String args[] )
   {
      StaticCharMethods application = new StaticCharMethods();

      //只有加上这一句,才能实现单击窗口关闭按钮关闭程序
      application.addWindowListener(
         new WindowAdapter() {
            public void windowClosing( WindowEvent e )
            {
               System.exit( 0 );	//退出系统
            }
         }
      );
   }
}