作业
// An addition program import javax.swing.JOptionPane; // import class JOptionPane public class Addition { public static void main( String args[] ) { String firstNumber, // first string entered by user secondNumber; // second string entered by user int number1, // first number to add number2, // second number to add sum; // sum of number1 and number2 // read in first number from user as a string firstNumber = JOptionPane.showInputDialog( "Enter first integer" ); // read in second number from user as a string secondNumber = JOptionPane.showInputDialog( "Enter second integer" ); // convert numbers from type String to type int number1 = Integer.parseInt( firstNumber ); number2 = Integer.parseInt( secondNumber ); // add the numbers sum = number1 + number2; // display the results JOptionPane.showMessageDialog( null, "The sum is " + sum, "Results", JOptionPane.PLAIN_MESSAGE ); System.exit( 0 ); // terminate the program } }
public class EnumTest { public static void main(String[] args) { Size s=Size.SMALL; Size t=Size.LARGE; //s��t����ͬһ������ System.out.println(s==t); // //��ԭʼ���������� System.out.println(s.getClass().isPrimitive()); //���ַ�����ת�� Size u=Size.valueOf("SMALL"); System.out.println(s==u); //true //�г���������ֵ for(Size value:Size.values()){ System.out.println(value); } } } enum Size{SMAL
/** @version 1.10 2004-02-10 @author Cay Horstmann */ import java.util.*; public class InputTest { public static void main(String[] args) { Scanner in = new Scanner(System.in); // get first input System.out.print("What is your name? "); String name = in.nextLine(); // get second input System.out.print("How old are you? "); int age = in.nextInt(); /* int i; String value="100"; i=Integer.parseInt(value); i=200; String s=String.valueOf(i);*/ // display output on console System.out.println("Hello, " + name + ". Next year, you'll be " + (age + 1)); } }
public class RandomStr { public static void main(String[] args) { //����һ�����ַ��� String result = ""; //����6��ѭ�� for(int i = 0 ; i < 6 ; i ++) { //����һ��97��122��int�͵����� int intVal = (int)(Math.random() * 26 + 97); //��intValueǿ��ת��Ϊchar�����ӵ�result���� result = result + (char)intVal; } //�������ַ��� System.out.println(result); } }
// Drawing shapes import java.awt.Graphics; import javax.swing.*; public class SwitchTest extends JApplet { int choice; public void init() { String input; input = JOptionPane.showInputDialog( "Enter 1 to draw lines\n" + "Enter 2 to draw rectangles\n" + "Enter 3 to draw ovals\n" ); choice = Integer.parseInt( input ); } public void paint( Graphics g ) { for ( int i = 0; i < 10; i++ ) { switch( choice ) { case 1: g.drawLine( 10, 10, 250, 10 + i * 10 ); break; case 2: g.drawRect( 10 + i * 10, 10 + i * 10, 50 + i * 10, 50 + i * 10 ); break; case 3: g.drawOval( 10 + i * 10, 10 + i * 10, 50 + i * 10, 50 + i * 10 ); break; default: JOptionPane.showMessageDialog( null, "Invalid value entered" ); } // end switch } // end for } // end paint() } // end class SwitchTest /************************************************************************** * (C) Copyright 1999 by Deitel & Associates, Inc. and Prentice Hall. * * All Rights Reserved. * * * * DISCLAIMER: The authors and publisher of this book have used their * * best efforts in preparing the book. These efforts include the * * development, research, and testing of the theories and programs * * to determine their effectiveness. The authors and publisher make * * no warranty of any kind, expressed or implied, with regard to these * * programs or to the documentation contained in these books. The authors * * and publisher shall not be liable in any event for incidental or * * consequential damages in connection with, or arising out of, the * * furnishing, performance, or use of these programs. * *************************************************************************/
import java.math.BigDecimal; public class TestBigDecimal { public static void main(String[] args) { BigDecimal f1 = new BigDecimal("0.05"); BigDecimal f2 = BigDecimal.valueOf(0.01); BigDecimal f3 = new BigDecimal(0.05); System.out.println("����ʹ��String��ΪBigDecimal�����������ļ�������"); System.out.println("0.05 + 0.01 = " + f1.add(f2)); System.out.println("0.05 - 0.01 = " + f1.subtract(f2)); System.out.println("0.05 * 0.01 = " + f1.multiply(f2)); System.out.println("0.05 / 0.01 = " + f1.divide(f2)); System.out.println("����ʹ��double��ΪBigDecimal�����������ļ�������"); System.out.println("0.05 + 0.01 = " + f3.add(f2)); System.out.println("0.05 - 0.01 = " + f3.subtract(f2)); System.out.println("0.05 * 0.01 = " + f3.multiply(f2)); System.out.println("0.05 / 0.01 = " + f3.divide(f2)); } }
public class TestDouble { public static void main(String args[]) { System.out.println("0.05 + 0.01 = " + (0.05 + 0.01)); System.out.println("1.0 - 0.42 = " + (1.0 - 0.42)); System.out.println("4.015 * 100 = " + (4.015 * 100)); System.out.println("123.3 / 100 = " + (123.3 / 100)); } }
课堂随机测试
import java.util.Scanner; import java.util.Random; public class Main { public static void main(String[] args) { Random radom=new Random(); for(int i=0;i<30;i++) { int k= radom.nextInt(100)%100; int t=radom.nextInt(100)%100; int sf= radom.nextInt(4)%4; if (sf == 0) { System.out.println(k + "+" + t + "="); } if (sf == 1) { System.out.println(k + "-" + t + "="); } if (sf == 2) { System.out.println(k + "/" + t + "="); } if (sf == 3) { System.out.println(k + "*" + t + "="); } } } }