Chapter 12, Problem 1E

Repeat Exercise 2 in Chapter 7, but use an instance of ArrayList instead of an array. Do not read the number of values, but continue to read values until the user enters a negative value.

Explanation of Solution

Program Plan:

• Import required package.
• Define “CountFamiles”class.
  • Define main function.
    • Create object for scanner class.
    • Create array “incomeArr” by using “ArrayList”.
    • Display the prompt statement.
    • Assign “additionalValues” to “true”.
    • Initializes required variable.
    • Read input of income from user up to the value of “additionalValues” is “false”.
      • Display prompt statement for each family.
      • Read each family income from user and store it to “incomeValues”.
      • If “incomeValues” is less than “0”, then set “additionalValues” to “false”.
      • Otherwise, add the “incomeValues” to array “incomeArr”.
      • Increment the index.
    • Compute maximum income using “for” loop.
      • If “incomeArr.get(i)” is greater than maximum income, then assign maximum income to “incomeArr.get(i)”.
    • Display maximum income.
    • Display “10” percent of maximum income by “0.1 * maximumIncome”.
    • Initializes the count value to “0”.
    • Compute the count of families with incomes less than “10” percentage of maximum income using “for” loop.
      • Check condition. If value of “incomeArr.get(i)” is less than “0.1 * maximumIncome”, then increment count value and display the family income with less than “10” percentage of income by family wise.
    • Finally display the count of families.

Program:

The below java program is used to counts the number of families with less than “10” percent of maximum income using array.

“CountFamiles.java”

//Import required package

import java.util.*;

//Define "CountFamiles" class

public class CountFamiles

{

    //Define main function

    public static void main(String[] args)

    {

        //Create object for scanner class

        Scanner input = new Scanner(System.in);

/* Create array "incomeArr" by using "ArrayList" */

ArrayList<Double> incomeArr = new ArrayList<Double>();

        //Display the prompt statement

System.out.println("Enter the income for each family. Use a negative value to indicate the end ");

        //Assign "additionalValues" to "true"

        boolean additionalValues = true;

        //Initializes required variable

        int i = 0;

/* Read input of income from user upto the value of "additionalValues" is "false" */

        while(additionalValues)

        {

//Display prompt statement for each family

System.out.print("Enter Income for family " + (i +1) + ": ");

/* Read each family income from user and store it to "incomeValues" */

double incomeValues = input.nextDouble();

/* If "incomeValues" is less than "0", then */

            if(incomeValues < 0)

                /* Set "additionalValues" to "false" */

                additionalValues = false;

            /* Otherwise */

            else

/* Add the "incomeValues" to array "incomeArr" */

                incomeArr.add(incomeValues);

            //Increment the index

            i++;

        }

        //Compute maximum income using "for" loop

        double maximumIncome = incomeArr.get(0);

        for(i  = 0; i < incomeArr.size(); i ++)

        {

/* If incomeArr.get[i] is greater than maximum income, then */

            if(incomeArr.get(i) > maximumIncome)

//Assign maximum income to "incomeArr.get(i)"

                maximumIncome = incomeArr.get(i);

        }

        //Display maximum income

System.out.println("The maximum income is: " + maximumIncome);

        //Display 10 percent of maximum income

System.out.println("10% of maximum income is: " + (0.1 * maximumIncome));

        //Display prompt statement

System.out.println("\nDisplaying all families with incomes less than 10% of the maximum income income");

        //Initializes the count value to "0"

        int countValue = 0;

//Compute the count of families with incomes less than 10% of maximum income

        for( i=0; i<incomeArr.size(); i++)

        {

            //Check condition

if(incomeArr.get(i) < (0.1 * maximumIncome))

            {

                //Increment count value

                countValue++;

/* Display the family income with less than 10 percentage of income by family wise */

System.out.println("Family " + (i+1) + " had income " + incomeArr.get(i));

            }

        }

        //Display count of families

System.out.println("Count of families with 10% of maximum income is: " + countValue);

    }

}

Sample Output

Output:

Enter the income for each family. Use a negative value to indicate the end

Enter Income for family 1: 10000

Enter Income for family 2: 48000

Enter Income for family 3: 20000

Enter Income for family 4: 12000

Enter Income for family 5: 300000

Enter Income for family 6: 40000

Enter Income for family 7: -1

The maximum income is: 300000.0

10% of maximum income is: 30000.0

Displaying all families with incomes less than 10% of the maximum income

Family 1 had income 10000.0

Family 3 had income 20000.0

Family 4 had income 12000.0

Count of families with 10% of maximum income is: 3