java语言程序设计基础课后习题第二章

//exercise 2.2
package secondchapterexercise1;

public class first01 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
            double miles=100;
            double KILOMETERS_PER_MILE=1.609;
            double kilometers=miles*KILOMETERS_PER_MILE;
            System.out.println(kilometers);
            final int SIZE=20;
            
    }

}

//exercise 2.1
package secondchapterexercise1;
import java.util.Scanner;
public class second02 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
            double celsius;
            double fahreheit;
            Scanner in=new Scanner(System.in);
            System.out.print("Enter a degree in  Celsius:");
            celsius=in.nextDouble();
            fahreheit=(9.0/5)*celsius+32;
            System.out.println(celsius+"Celsius is "+fahreheit+" Fahrenheit");
            
    }

}

//exercise 2.2
package secondchapterexercise1;
import java.util.Scanner;
public class third03 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
            final double PI =3.1415926;
            System.out.print("Enter the radius and length of a cylinder:");
            Scanner in =new Scanner (System.in);
            double radius=in.nextDouble();
            double length=in.nextDouble();
            double area=radius*radius*PI;
            System.out.println("The area is "+(int)(area*10000)/10000.0);
            double volume =area *length;
            System.out.println("The volume is "+(int)(volume*10)/10.0);
            
    }

}

//exercise 2.3
package secondchapterexercise1;
import java.util.Scanner;
public class fourth04 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter a value for feet:");
        double feet=in.nextDouble();
        double meter=feet*0.305;
        System.out.print(feet+" feet is "+meter+ "meters.");
    }

}

//exercise 2.4
package secondchapterexercise1;
import java.util.Scanner;
public class fifth05 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter a number in pounds :");
        double pounds=in.nextDouble();
        double kilograms=pounds*0.454;
        System.out.println(pounds+"pounds is "+(int)(kilograms*1000)/1000.0+"kilograms");
    }

}

//exercise 2-5
package secondchapterexercise1;
import java.util.Scanner;
public class sixth06 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter the subtotal and a gratuity rate :");
        double subtotal=in.nextDouble();
        double gratuity=in.nextDouble()/100.0;
        double gratuity1=subtotal*gratuity;
        double total=subtotal+gratuity1;
        System.out.println("The gratuity is "+gratuity1+"and total is "+total);
    }

}

//exercise 2.6
package secondchapterexercise1;
import java.util.Scanner;
public class seventh07 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        
        System.out.print("Enter a number between 0 and 1000:");
        int integer=in.nextInt();
        
        
        int a=integer%10,sum;
        if(integer/10==0)
        {
            sum=a;
            System.out.print("The sum of the figits is "+sum);
            System.exit(0);
        }
        
        
        integer=integer/10;
        int b=integer%10;
        if(integer/10==0)
        {
            sum=a+b;
            System.out.print("The sum of the figits is "+sum);
            System.exit(0);
        }
        
        
        integer=integer/10;
        sum=a+b+integer;
        System.out.print("The sum of the figits is "+sum);
    }

}

//exercise 2.7
package secondchapterexercise1;
import java.util.Scanner;
public class eighth08 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter the number of minues :");
        long minues = in.nextLong();
        long day=minues/1440;
        long year=day/365;
        day=day%365;
        System.out.print(minues+"minues is approximately "+year+" years and "+day+" days");
    }

}

//exercise 2.8
package secondchapterexercise1;
import java.util.Scanner;
public class ninth09 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter an ASCII code:");
        int integer=in.nextInt();
        char a=(char)integer;
        System.out.println("The character for ASCII code "+integer +" is "+a);
        
        
    }

}

//exercise 2-10
package secondchapterexercise1;
import javax.swing.JOptionPane;
public class tenth10 {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        String annualInterestRateString=JOptionPane.showInputDialog("Enter yearly int"
                + "erest rate,for example 8.25:");
        double annualInterestRate=Double.parseDouble(annualInterestRateString);
        double monthlyInterestRate=annualInterestRate/1200;
        String numberOfYearsString=JOptionPane.showInputDialog("Enter number of years "
                + "as an integer,
for example 5:");
        int numberOfYears=Integer.parseInt(numberOfYearsString);
        String loanString =JOptionPane.showInputDialog("Enter loan amountt,for examp"
                + "le 120000.95:");
        double loanAmount =Double.parseDouble(loanString);
        double monthlyPayment=loanAmount*monthlyInterestRate/(1
                -1/Math.pow(1+monthlyInterestRate,numberOfYears*12));
        double totalPayment=monthlyPayment*numberOfYears*12;
        
        monthlyPayment=(int)(monthlyPayment*100)/100.0;
        totalPayment=(int)(totalPayment*100)/100.0;
        
        String output="The monthly payment is "+monthlyPayment+"
The total "
                + "payment is "+totalPayment;
        JOptionPane.showMessageDialog(null,output);
        
        
        
    }

}

//exercise 2.11
package secondchapterexercise2;
import java.util.Scanner;
public class first {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in =new Scanner(System.in);
        System.out.print("Enter emplouee's name :");
        String name=in.next();
        System.out.print("Enter number of hours worked in a week:");
        int hour =in.nextInt();
        System.out.print("Enter hourly pay rate :");
        double hourlypayrate=in.nextDouble();
        System.out.print("Enter federal tax withholding rate :");
        double federaltaxrate=in.nextDouble();
        System.out.print("Enter state tax withholding rate:");
        double statetaxrate=in.nextDouble();
        System.out.println("Employee Name:"+name);
        System.out.println("Hours Worled :"+hour);
        System.out.println("Pay Rate : $"+hourlypayrate);
        System.out.println("Gross Pay: $"+hourlypayrate*10);
        System.out.println("Deductions:");
        double federalWithholding=hour*hourlypayrate*federaltaxrate;
        System.out.println("  Federal Withholding ("+(federaltaxrate*1000)/10.0+"%):"
                + " $"+federalWithholding);
        double StateWithholding=hour*hourlypayrate*statetaxrate;
        System.out.println("  State Withholding ("+statetaxrate*1000/10.0+"%)"
                + ": $"+StateWithholding);
        double totalDeduction=federalWithholding+StateWithholding;
        System.out.println("  Total Deduction:  $"+totalDeduction);
        double NetPay=hour*hourlypayrate-totalDeduction;
        System.out.println("Net Pay:  $"+NetPay);
        
        
    }

}

//exercise 2.11
package secondchapterexercise2;

import javax.swing.JOptionPane;

public class second {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        //input name 
        String name=JOptionPane.showInputDialog("Enter employee's name:");
        
        //input hours
        String hours=JOptionPane.showInputDialog("Enter number of hours worked i"
                + "n a week:");
        int hour=Integer.parseInt(hours);
        
        //input hourly pay rate
        String hourlypayrate1=JOptionPane.showInputDialog("Enter hourly pay rateL");
        double hourlypayrate=Double.parseDouble(hourlypayrate1);
        
        //input federal tax withholding rate
        String federaltaxwithholdingrate1=JOptionPane.showInputDialog("Enter federal tax wit"
                + "hholding rate:");
        double federaltaxwithholdingrate=Double.parseDouble(federaltaxwithholdingrate1);
        
        //input state tax withholding rate
        String statetaxwithholdingrate1=JOptionPane.showInputDialog("Enter state tax withh"
                + "olding rate:");
        double statetaxwithholdingrate=Double.parseDouble(statetaxwithholdingrate1);
        
        //assignment
        double federalWithholding=hour*hourlypayrate*federaltaxwithholdingrate;    //assignment
        double StateWithholding=hour*hourlypayrate*statetaxwithholdingrate;        //assignment
        double totalDeduction=federalWithholding+StateWithholding;                //assignment
        double NetPay=hour*hourlypayrate-totalDeduction;                        //assignment
        
        
        String output ="Employee Name:"+name+"
Hours Worked:"+hour+"
Pay Rate :"+hourlypayrate+
                "
Gross Pay:"+hourlypayrate*10+"
Deductions:
  Federal Withholding("
                +federaltaxwithholdingrate*1000/10.0+"%):  $"+federalWithholding+"
  State Wi"
                        + "thholding ("+statetaxwithholdingrate*1000/10.0+"%):  $"
                                + ""+StateWithholding+"
  Total Deduction:  $"+totalDeduction+
                                "
Net Pay:  $"+NetPay;
        
        //output
        JOptionPane.showMessageDialog(null,output);
        
    }

}

//exercise 2.12
package secondchapterexercise2;
import java.util.Scanner;
import javax.swing.JOptionPane;
public class third {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter balance and interest rate (e.g., 3for3%):");
        int income =in.nextInt();
        double yearrate=in.nextDouble();
        double interest=income*(yearrate/1200);
        System.out.println("The interest is "+interest);
        
        //Dialog input
        String income1 =JOptionPane.showInputDialog("Enter income:");
        String interestrate=JOptionPane.showInputDialog("Enter interest rate");
        int  incomefirst=Integer.parseInt(income1);
        double interestrate1=Double.parseDouble(interestrate);
        double interest1 =incomefirst*(interestrate1/1200);
        JOptionPane.showMessageDialog(null, "The interest is"+interest1);
        
    }

}

//exercise 2.13
package secondchapterexercise2;
import java.util.Scanner;
public class fifth {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("input investment amount and annually interest rate and number of"
                + " years:");
        int investmentAmount=in.nextInt();
        double annuallyInterestrate=in.nextDouble()/100;
        int numberOfYears=in.nextInt();
        double futureinvestmentValue=investmentAmount*
                (Math.pow((1+annuallyInterestrate),numberOfYears));
        System.out.println("Accumulatted value is "+futureinvestmentValue);
    }

}

//exercise 2.14
package secondchapterexercise2;
import java.util.Scanner;
public class sixth {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter weight in pounds:");
        double weight=in.nextDouble();
        System.out.print("Enter height in inches:");
        int height =in.nextInt();
        double kilograms=weight*0.45359237;
        double meter=height*0.0254;
        double bmi=kilograms/Math.pow(meter, 2);
        System.out.println("BMI is "+bmi);
    }

}

//exercise 2.15
package secondchapterexercise2;

public class seventh {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int mouthlysalary=100;
        double sum=0;
        double mouthlyinterestrate=0.00417;
        sum=mouthlysalary*(1+mouthlyinterestrate);        //After the first mouth
        System.out.println("After the first mouth,money is :"+sum);
        sum=(sum+mouthlysalary)*(1+mouthlyinterestrate);//After the second mouth
        System.out.println("After the second mouth,money is :"+sum);
        sum=(sum+mouthlysalary)*(1+mouthlyinterestrate);//After the third mouth
        System.out.println("After the third mouth,money is :"+sum);
        sum=(sum+mouthlysalary)*(1+mouthlyinterestrate);//After the fourth mouth
        System.out.println("After the fourth mouth,money is :"+sum);
        sum=(sum+mouthlysalary)*(1+mouthlyinterestrate);//After the fifth mouth
        System.out.println("After the fifth mouth,money is :"+sum);
        sum=(sum+mouthlysalary)*(1+mouthlyinterestrate);//After the sixth mouth
        System.out.println("After the six mouth,money is :"+sum);
        
    }

}

//exercise 2.16
package secondchapterexercise2;
import java.util.Scanner;
public class eighth {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter the amount of water in killograms :");
        double kilograms=in.nextDouble();
        System.out.print("Enter the initial temperature:");
        double initialtemperature=in.nextDouble();
        System.out.print("Enter final temperature:");
        double finaltemperature=in.nextDouble();
        double energy=kilograms*(finaltemperature-initialtemperature)*4184;
        System.out.println("The energy needed is "+energy);
    }

}

//exercise 2.17
package secondchapterexercise2;
import java.util.Scanner;
public class ninth {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        
        System.out.println("please input -58F to 41F of temperature and better than 2 of "
                + "wind speed!!");
        
        //input Fahrenheit
        System.out.print("Enter the temperature in Fahrenheit:");
        double fahreheit=in.nextDouble();
        
        //input wind speed
        System.out.print("Enter the wind speed miles per hours:");
        double windspeed=in.nextDouble();
        
        double windchillindex=35.74+0.6215*fahreheit-35.75*Math.pow(windspeed,0.16)+
                0.4275*fahreheit*Math.pow(windspeed,0.16);
        System.out.print("The wind chill index is "+windchillindex);        
    }

}

//exercise 2.18
package secondchapterexercise2;

public class tenth {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        int a=1,b=2;
        int c;
        System.out.println("a	b	pow(a,b)");
        for(int i=1;i<=5;i++){
            c=(int)Math.pow(a, b);
            System.out.println(a+"	"+b+"	"+c);
            a++;
            b++;
            
        }
    }

}

//exercise 2.19
package secondchapterexercise3;

public class first {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        long time=System.currentTimeMillis();
        long a=time%26+65;
        char b=(char)a;
        System.out.print(b);
    }

}

//exercise 2.20
package secondchapterexercise3;
import java.util.Scanner;
public class second {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter x1 and y1:");
        double x1=in.nextDouble(),y1=in.nextDouble();
        System.out.print("Enter x2 and y2:");
        double x2=in.nextDouble(),y2=in.nextDouble();
        
        //calculation distance of two points
        double distance;
        distance=Math.pow((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1),0.5);
        System.out.println("The distance of the two points is"+distance);
    }

}

//exercise 2.21
package secondchapterexercise3;
import java.util.Scanner;;
public class third {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter three points for a triangle:");
        
        //input three points
        double x1=in.nextDouble();
        double y1=in.nextDouble();
        double x2=in.nextDouble();
        double y2=in.nextDouble();
        double x3=in.nextDouble();
        double y3=in.nextDouble();
        
        //calculation three side
        double side1=Math.pow((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1),0.5);
        double side2=Math.pow((x3-x1)*(x3-x1)+(y3-y1)*(y3-y1),0.5);
        double side3=Math.pow((x2-x3)*(x2-x3)+(y2-y3)*(y2-y3),0.5);
        
        double s=(side1+side2+side3)/2;
        
        //calculation area
        double area=Math.pow(s*(s-side1)*(s-side2)*(s-side3),0.5);
        System.out.println("The area of the triangle is "+area);
        
    }

}

//exercise 2.22
package secondchapterexercise3;
import java.util.Scanner;
public class fouth {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter the side:");
        double side=in.nextDouble();
        double area =3*(Math.pow(3, 0.5))/2*side*side;
        System.out.println("The area of the hexagon is "+area);
        
    }

}

//exercise 2.23
package secondchapterexercise3;
import java.util.Scanner;
public class fifth {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in =new Scanner(System.in);    
        System.out.print("Enter v0,v1,and t:");
        double v0=in.nextDouble();
        double v1=in.nextDouble();
        double time =in.nextDouble();
        double a=(v1-v0)/time;
        System.out.println("The average acceleration is "+a);
    }

}

//exercise 2.24
package secondchapterexercise3;
import java.util.Scanner;
public class sixth {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner in=new Scanner(System.in);
        System.out.print("Enter v and a:");
        double v=in.nextDouble();
        double a=in.nextDouble();
        double length=Math.pow(v,2)/(2*a);
        System.out.println("The minimum runway length for this airplane is "+length);
    }

}