java练习程序1

 /*import javax.swing.JFrame;*/
/*import javax.swing.JOptionPane;*/
public class TestFrame{
public static void main(String[] args) throws Exception{
/*JFrame frame1 = new JFrame();
frame1.setTitle("Windows 1");
frame1.setSize(200,150);
frame1.setLocation(200,100);
frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame1.setVisible(true);

JFrame rx = new JFrame();
rx.setTitle("rx's Windows");
rx.setSize(300,300);
rx.setLocation(0,0);
rx.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
rx.setVisible(true);*/

/*String s = "Welcome to java";
String s1 = new String("Welcome to java");

String s2 = s1.intern();
String s3 = "Welcome to java";

System.out.println("s1 == s is" + (s1 == s));
System.out.println("s2 == s is" + (s2 == s));
System.out.println("s.intern() == s3.intern() is" + (s.intern() == s3.intern()));

String s4 = "Welcome";
String s5 = "j a v a";

System.out.println();
System.out.println(s4.toLowerCase());
System.out.println(s4.toUpperCase());
System.out.println(s5.trim());
System.out.println(s4.replace('e','A'));
System.out.println(s4.replaceAll("e","E"));*/

/*System.out.println("Welcome to java".indexOf('W'));
System.out.println("Welcome to java".indexOf('o'));
System.out.println("Welcome to java".indexOf('o',5));
System.out.println("Welcome to java".indexOf("come"));
System.out.println("Welcome to java".indexOf("java",5));
System.out.println("Welcome to java".indexOf("Java",5));

System.out.println("Welcome to java".lastIndexOf('W'));
System.out.println("Welcome to java".lastIndexOf('o'));
System.out.println("Welcome to java".lastIndexOf('o',5));
System.out.println("Welcome to java".lastIndexOf("come"));
System.out.println("Welcome to java".lastIndexOf("java",5));
System.out.println("Welcome to java".lastIndexOf("Java",5));*/


/*char[] chars = "Java".toCharArray();
getChars(int srcBegin,int