Java程序辅导
C C++ Java Python Processing编程在线培训 程序编写 软件开发 视频讲解
C C++ Java Python Processing编程在线培训 程序编写 软件开发 视频讲解
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CS 1301
Lab 3
Working with Selections – Chapter 3
Use JGrasp to complete, compile, and run the following programs (in separate java files) and understand what
they do. Save all programs for future reference as they illustrate essential programming concepts and syntax
that you may use in other labs and Assignments.
//********************************************************************
// Age.java Author: Lewis/Loftus
// Demonstrates the use of if statements.
//********************************************************************
import java.util.Scanner;
public class Age
{
//-----------------------------------------------------------------
// Reads the user's age and prints comments accordingly.
//-----------------------------------------------------------------
public static void main (String[] args)
{
final int MINOR = 21;
Scanner scan = new Scanner (System.in);
System.out.print ("Enter your age: ");
int age = scan.nextInt();
System.out.println ("You entered: " + age);
if (age < MINOR)
System.out.println ("Youth is a wonderful thing. Enjoy.");
System.out.println ("Age is a state of mind.");
}
}
//********************************************************************
// Wages.java Author: Lewis/Loftus
// Demonstrates the use of an if-else statement.
//********************************************************************
import java.text.NumberFormat;
import java.util.Scanner;
public class Wages
{
//-----------------------------------------------------------------
// Reads the number of hours worked and calculates wages.
//-----------------------------------------------------------------
public static void main (String[] args)
{
final double RATE = 8.25; // regular pay rate
final int STANDARD = 40; // standard hours in a work week
double pay = 0.0;
Scanner scan = new Scanner (System.in);
System.out.print ("Enter the number of hours worked: ");
int hours = scan.nextInt();
System.out.println ();
// Pay overtime at "time and a half"
if (hours > STANDARD)
pay = STANDARD * RATE + (hours-STANDARD) * (RATE * 1.5);
else
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pay = hours * RATE;
NumberFormat fmt = NumberFormat.getCurrencyInstance();
System.out.println ("Gross earnings: " + fmt.format(pay));
}
}
//********************************************************************
// Guessing.java Author: Lewis/Loftus
// Demonstrates the use of a block statement in an if-else.
//********************************************************************
import java.util.*;
public class Guessing
{
//-----------------------------------------------------------------
// Plays a simple guessing game with the user.
//-----------------------------------------------------------------
public static void main (String[] args)
{
final int MAX = 100;
int answer, guess;
Scanner scan = new Scanner (System.in); // scanner object
Random generator = new Random(); // random number generator object
answer = generator.nextInt(MAX) + 1;
System.out.print ("I'm thinking of a number between 1 and "
+ MAX + ". Guess what it is: ");
guess = scan.nextInt();
if (guess == answer)
System.out.println ("You got it! Good guessing!");
else
{
System.out.println ("That is not correct, sorry.");
System.out.println ("The number was " + answer);
}
}
}
//********************************************************************
// MinOfThree.java Author: Lewis/Loftus
// Demonstrates the use of nested if statements.
//********************************************************************
import java.util.Scanner;
public class MinOfThree
{
//-----------------------------------------------------------------
// Reads three integers from the user and determines the smallest
// value.
//-----------------------------------------------------------------
public static void main (String[] args)
{
int num1, num2, num3, min = 0;
Scanner scan = new Scanner (System.in);
System.out.println ("Enter three integers: ");
num1 = scan.nextInt();
num2 = scan.nextInt();
num3 = scan.nextInt();
if (num1 < num2)
if (num1 < num3)
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min = num1;
else
min = num3;
else
if (num2 < num3)
min = num2;
else
min = num3;
System.out.println ("Minimum value: " + min);
}
}
//********************************************************************
// GradeReport.java Author: Lewis/Loftus
// Demonstrates the use of a switch statement.
//********************************************************************
import java.util.Scanner;
public class GradeReport
{
//-----------------------------------------------------------------
// Reads a grade from the user and prints comments accordingly.
//-----------------------------------------------------------------
public static void main (String[] args)
{
int grade, category;
Scanner scan = new Scanner (System.in);
System.out.print ("Enter a numeric grade (0 to 100): ");
grade = scan.nextInt();
category = grade / 10;
System.out.print ("That grade is ");
switch (category)
{
case 10:
System.out.println ("a perfect score. Well done.");
break;
case 9:
System.out.println ("well above average. Excellent.");
break;
case 8:
System.out.println ("above average. Nice job.");
break;
case 7:
System.out.println ("average.");
break;
case 6:
System.out.println ("below average. You should see the");
System.out.println ("instructor to clarify the material "
+ "presented in class.");
break;
default:
System.out.println ("not passing.");
}
}
}
Now, use the above programs for guidance to complete, compile, and run the following practice programs.
Exercise #1: Write a Java program (name it Practice_3_1) that reads from the user four grades between 0
and 100. The program then, on separate lines, prints out the entered grades followed by the highest grade,
lowest grade, and averages of all four grades. Make sure to properly label your output. Use escape character to
line-up the outputs after the labels.
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Exercise #2: Write a Java program (name it Practice_3_2) that generates a random number between 0 and
100 (representing a grade) (see program Guessing.java above or section 3.7 on how to generate random
numbers). The program then, on separate lines, prints out the generated grade followed by the corresponding
letter grade (A, B, C, D, F) using the standard scale below. Label your output properly and use escape
characters to lineup the outputs after the labels.
90 – 100: A
80 – 89: B
70 – 79: C
60 – 69: D
00 – 59: F
Exercise #3: Write a Java program (name it Practice_3_3) to implement a solution for the following problem.
The cost of international call from Atlanta to Beijing is calculated as follows:
Connection fee is $1.99; $2.00 for first three minutes; and $.45 for each additional minute.
The program prompts the user to enter the minutes, then should output the call duration followed by the amount
due. Use currency object format. Use proper labels and line-up your outputs using escape characters.
Exercise #4: Write a Java program (name it Practice_3_4) that prompts the user to enter the x-coordinate
and y-coordinate of a point (in a Cartesian plane). The program should then output a message indicating
whether the point is the origin, is located on the x-axis, is located on the y-axis, or appears in a particular
quadrant. For example:
(0,0) is the origin
(4,0) is on the x-axis
(0,-3) is on the y-axis
(-2,3) is in the second quadrant
Document your code properly and lineup the outputs as shown above.
Instructions:
1. Programs must be working correctly.
2. Programs must be completed and checked before working assignment #3.
3. Programs must be checked by the end of the designated lab session.