3-1

import java.util.Scanner;

public class AdditionQuiz
{
public static void main(String[] args)
{
int number1=(int)(System.currentTimeMillis()%10);
int number2=(int)(System.currentTimeMillis()/7%10);
Scanner input=new Scanner(System.in);

System.out.print(
"What is "+number1+"+"+number2+"?");
int answer = input.nextInt();
System.out.println(
number1+"+"+number2+"="+answer+" is "+(number1+number2==answer));
}
}

3-2

import java.util.Scanner;

public class SimpleIfDemo
{
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);
System.out.println("Enter an integer:");
int number = input.nextInt();
if (number % 5 == 0)
System.out.println("HiFive");
if(number % 2 == 0)
System.out.println("HiEven");
}
}

3-3

import java.util.Scanner;

public class SubtractionQuiz
{
public static void main(String[] args)
{
int number1 = (int)(Math.random() * 10);
int number2 = (int)(Math.random() * 10);

if (number1 < number2)
{
int temp = number1;
number1 = number2;
number2 = temp;
}
System.out.print
("What is " + number1 + "-" + number2 + "?");
Scanner input = new Scanner(System.in);
int answer = input.nextInt();
if (number1 - number2 == answer)
System.out.println("You are correct!");
else{
System.out.println("Your answer is wrong.");
System.out.println(number1 + "-" + number2 + "should be " + (number1-number2));
}
}
}

3-4

import java.util.Scanner;

public class ComputeAndInterpretBMI
{
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);

System.out.print("Enter weight in kilograms:");
double weight = input.nextDouble();

System.out.print("Enter height in meters:");
double height = input.nextDouble();

double bmi = weight/(height * height);

System.out.println("BMI is " + bmi);
if (bmi < 18.5)
System.out.println("Underweight");
else if (bmi < 25)
System.out.println("Normal");
else if (bmi < 30)
System.out.println("Overweight");
else
System.out.println("Obese");
}
}

3-6

import java.util.Scanner;

public class TestBooleanOperators
{
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);

System.out.print("Enter an integer:");
int number = input.nextInt();
if (number % 2 == 0 && number % 3 ==0)
System.out.println(number + " is divisible by 2 and 3.");
if (number % 2 == 0 || number % 3 ==0)
System.out.println(number + " is divisible by 2 or 3.");
if (number % 2 == 0 ^ number % 3 ==0)
System.out.println(number + " is divisible by 2 or 3, but not both.");
}
}

3-7

import java.util.Scanner;

public class LeapYear
{
public static void main(String[] args)
{
Scanner input = new Scanner(System.in);

System.out.print("Enter a year:");
int year = input.nextInt();
boolean isLeapYear = (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0);
System.out.println(year + " is a leap year?" + isLeapYear);
}
}

第四周