作业.

3-1

import java.util.Scanner;
public class Application {
　　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 SimpleIfDome {
　　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.print("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 pounds: ");
　　double weight = input.nextDouble();
　　System.out.print("Enter height in inches:");
　　double height = input.nextDouble();
　　final double KILOGRAMS_PER_POUND = 0.45359237;
　　final double METERS_PER_INCH = 0.0254;
　　double weightInKilograms = weight * KILOGRAMS_PER_POUND ;
　　double heightInMeters = height * METERS_PER_INCH;
　　double bmi = weightInKilograms/(heightInMeters * heightInMeters);
　　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);
　　}

}