以下为课件中动手动脑问题的实验代码:
1、
import javax.swing.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
}
}
2、
public class EnumTest {
public static void main(String[] args) {
Size s=Size.SMALL;
Size t=Size.LARGE;
//s和t引用同一个对象？
System.out.println(s==t); //
//是原始数据类型吗？
System.out.println(s.getClass().isPrimitive());
//从字符串中转换
Size u=Size.valueOf("SMALL");
System.out.println(s==u); //true
//列出它的所有值
for(Size value:Size.values()){
System.out.println(value);
}
}
}
enum Size{SMALL,MEDIUM,LARGE};
3、
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));
}
}
4、
public class RandomStr
{
public static void main(String[] args)
{
//定义一个空字符串
String result = "";
//进行6次循环
for(int i = 0 ; i < 6 ; i ++)
{
//生成一个97～122的int型的整数
int intVal = (int)(Math.random() * 26 + 97);
//将intValue强制转换为char后连接到result后面
result = result + (char)intVal;
}
//输出随机字符串
System.out.println(result);
}
}
5、
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
6、
public class Test {
public static void main(String[] args) {
int intValue=100;
long longValue=intValue;
double doubleValue=1234567890;
float floatValue=(float)doubleValue;
System.out.println(floatValue);//1.23456794E9
int X=100;
int Y=200;
System.out.println("X+Y="+X+Y);
System.out.println(X+Y+"=X+Y");
doNotRunme();
String string="";
double d1=1000.123;
double d2=1000.123;
if(Math.abs(d2-d1)<1e-10){
}
//System.out.println(string);
}
public static void doNotRunme()
{
doNotRunme();
}
}
7、
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("下面使用String作为BigDecimal构造器参数的计算结果：");
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("下面使用double作为BigDecimal构造器参数的计算结果：");
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));
}
}
8、
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));
}
}
二、以下为课后作业中的实验代码：
1、以下为随机生成30道的小学计算题的源代码
//信1705-2 何伟豪 20173629
package 小学计算题;
import java.util.Random; //随机生成数字的头文件
import java.util.Scanner; //输入整型数据的头文件
public class count {
public static void main(String args[]) {
Scanner cin=new Scanner(System.in);
Random random = new Random();
for(int i=0;i<30;i++) //输出30个数的循环 开始1
{
double sum=0;
int a=random.nextInt(101); //随机生成100以内的一个数
int b=random.nextInt(101); //再随机生成100以内的一个数
System.out.print(a); //输出a
int tatted; //存储代表运算符的数
tatted=random.nextInt(3); //随机生成代表运算符的数
if(tatted==0) { //将代表运算符的数转化为运算符 开始2
System.out.print("+");
sum=a+b;
}else if(tatted==1) {
System.out.print("-");
sum=a-b;
}else if(tatted==2) {
System.out.print("*");
sum=a*b;
}else if(tatted==3) {
System.out.print("/");
sum=a/b;
} //数转化为运算符 结束2
System.out.print(b);//输出b
System.out.print("="); //输出等于号
double sum0 = cin.nextInt(); //输入得数
if(sum0==sum) {
System.out.println("答案正确");
}else {
System.out.println("答案错误");
}
} //输出30个数的循环 结束1
cin.close();
}
}
2、以下为模拟的登录界面（随机生成验证码）的源代码
package 验证码;
import javax.swing.JOptionPane;
import java.util.Random;
public class textpass {
public static void main( String args[] )
{
Random random = new Random();
int a=random.nextInt(10); //随机生成0-9以内的一个数
int b=random.nextInt(10); //随机生成0-9以内的一个数
int c=random.nextInt(10); //随机生成0-9以内的一个数
int d=random.nextInt(10); //随机生成0-9以内的一个数
String name , mima , yan;
//输入登录名
name =
JOptionPane.showInputDialog( "登录名：" );
//输入密码
mima =
JOptionPane.showInputDialog( "密码：" );
//输入验证码
yan =
JOptionPane.showInputDialog( "验证码：" + a + " " + b + " " + c + " " + d );
//最终显示
JOptionPane.showMessageDialog(
null, "登录名：" + name + " 密码：" + mima +" 验证码：" +yan, "Results",
JOptionPane.PLAIN_MESSAGE );
System.exit( 0 );
}
}