Java Average Program | 易学教程

问题

Write a class called Average that can be used to calculate average of several integers. It should contain the following methods:

A method that accepts two integer parameters and returns their average.
A method that accepts three integer parameters and returns their average.
A method that accepts two integer parameters that represent a range.

Issue an error message and return zero if the second parameter is less than the first one. Otherwise, the method should return the average of the integers in that range (inclusive). Implement the class and write a program to test its methods and submit your source code (.java files).

I am stuck on part three, I don't even really understand the stipulation. Will I be using a floating point / double? Here is the program I have thus far:

import java.util.Scanner;

public class Average {

  public static void main(String[] args) {
    int numb1, numb2, numb3, userInput;
    System.out.println("Enter '2' if you wish to average two numbers enter '3' if you wish to average 3.");
    Scanner keyboard = new Scanner(System.in);
    userInput = keyboard.nextInt();
    if (userInput == 2){
      System.out.println("Enter two numbers you'd like to be averaged.");
      numb1 = keyboard.nextInt();
      numb2 = keyboard.nextInt();
      Average ave = new Average();
      System.out.println("The average is: " + ave.average(numb1, numb2));
      System.exit(1);
    }
    if(userInput == 3){
      System.out.println("Enter three numbers you'd like to be averaged.");
      numb1 = keyboard.nextInt();
      numb2 = keyboard.nextInt();
      numb3 = keyboard.nextInt();
      Average ave = new Average();
      System.out.println("The average is: " + ave.average(numb1, numb2, numb3));
      System.exit(1);
    }
  }
  public static int average (int num1, int num2) {
    return (num1 + num2) / 2;
  } 
  public static int average (int numb1, int numb2, int numb3){ 
    return (numb1 + numb2 + numb3) / 3; 
  } 
}

回答1:

Not really here to do your homework, but since I'm already here, the range is the difference between the largest and smallest number.

public int returnRange(int first, int second) {
    if(first > second)
        return first-second;
    else
        return second-first;
}

To make things easier though...

public double returnAverage(int...numbers) {
    for(int i = 0; i < numbers.length(); i++) {
        total += numbers;
    }

    return total/numbers.length();
}

public int returnRange(int...numbers) {
    int holder = 0;

    int highest;
    int lowest;

    for(int i = 0; i < numbers.length(); i++) {
        if(numbers[i] > holder) {
            holder = numbers[i];
    }
    highest = holder;

    for(int i = 0; i < numbers.length(); i++) {
        if(numbers[i] < holder) {
            holder = numbers[i];
        }
    }
    lowest = holder;

    return highest-lowest;
}

Last 2 methods are un-tested, but from experience, should work fine. These methods have arrays for the parameters, so you can do as many numbers as you'd like.

回答2:

Please don't re-ask the same question as you just asked here: http://stackoverflow.com/questions/19507108/java-averaging-program

Rather update your other post to reflect your new code / questions.

Now onto your question:

A method that accepts two integer parameters that represent a range. Issue an error message and return zero if the second parameter is less than the first one. Otherwise, the method should return the average of the integers in that range (inclusive). Implement the class and write a program to test its methods and submit your source code (.java files).

Lets start by declaring our method and we'll declare it as static to conform to your program (since you're not creating your own objects). Then we want to check if the parameters follow the assignment instructions and return values accordingly.

public static int getRange(int firstValue, int secondValue)
    {
        int range;
        if (firstValue > secondValue)
            range = firstValue - secondValue;
        else
        {
            range = 0;
            System.out.println("Error!");
        }
        return range;
    }

**To promote your understanding it's up to you to find the average of the integers in the range!

回答3:

In your main method check for -1 and return error when first value is greater than second

public double avgRange(int a, int b){

    if(a>b){
        return -1;
    }
    else{
        double total=0;
        for(int x=a; x<=b; x++){
            total = total + x;
        }
        return total/(b-a+1);
    }
}

回答4:

the method should return the average of the integers in that range (inclusive).

You're asked to return the average of all integers in the range bounded by the two parameters.

For example, if parameters were 5 and 10, the method should return the average of 5, 6, 7, 8, 9, and 10, which is 7.5. (5 and 10 are included because the question says the range should be "inclusive".)

To find the average, use a for loop to sum each integer in the range, then divide by the number of integers.

Will I be using a floating point / double?

The return value should be a float or double, since the average isn't always a whole number.

来源：https://stackoverflow.com/questions/19507832/java-average-program

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java

average