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Overview

This page documents the core array operations in the Actividad-1 application, including user input collection, difference calculations, average computation, and formatted output.

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Array Input Operations

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First Array Input (Lines 14-19)

The first loop collects 7 integer values from the user and stores them in array1:
Main.java:14-19
System.out.println("Ingrese 7 valores para el primer arreglo");
for (int i = 0; i < array1.length; i++) {
    System.out.print("Valor " + (i + 1) + ": ");
    array1[i] = sc.nextInt();
    sumaTotal += array1[i];
}
Key Features:
  • Prompts user with “Ingrese 7 valores para el primer arreglo”
  • Uses zero-based indexing (i) but displays one-based numbering (i + 1) for user clarity
  • Reads each integer using sc.nextInt()
  • Accumulates sum: Each input value is immediately added to sumaTotal (line 18)
  • Loop iterates based on array1.length for maintainability

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Second Array Input (Lines 21-26)

This section contains a critical bug that affects the average calculation.
The second loop collects 7 integer values for array2:
Main.java:21-26
System.out.println("Ingrese 7 valores para el segundo arreglo");
for (int i = 0; i < array1.length; i++) {
    System.out.print("Valor " + (i + 1) + ": ");
    array2[i] = sc.nextInt();
    sumaTotal += array1[i];  // BUG: Should be array2[i]
}
Bug Description:
Main.java:25
sumaTotal += array1[i];  // Incorrect: adds array1 values again
Expected Behavior:
sumaTotal += array2[i];  // Correct: should add array2 values
Impact:
  • The sum accumulates array1 values twice instead of including array2 values
  • This causes the average calculation to be incorrect
  • The bug results in: average = (sum(array1) * 2) / 14 instead of (sum(array1) + sum(array2)) / 14
Example:If array1 = [1, 2, 3, 4, 5, 6, 7] and array2 = [10, 20, 30, 40, 50, 60, 70]:
  • Actual sum: 28 + 28 = 56 (array1 counted twice)
  • Expected sum: 28 + 280 = 308
  • Actual average: 56 / 14 = 4.0
  • Expected average: 308 / 14 = 22.0

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Difference Calculation (Lines 29-31)

Calculates element-wise differences between the two arrays:
Main.java:29-31
// Diferencia
for (int i = 0; i < array1.length; i++) {
    arrayDiferencia[i] = array1[i] - array2[i];
}
Logic:
  • Iterates through each index from 0 to 6
  • Subtracts corresponding elements: arrayDiferencia[i] = array1[i] - array2[i]
  • Stores results in the arrayDiferencia array
Example:
Indexarray1[i]array2[i]arrayDiferencia[i]
01055
11587
220128
379-2
430255
51820-2
622157

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Average Calculation (Line 34)

Computes the average of all input values using explicit type casting:
Main.java:34
double promedio = (double) sumaTotal / totalElementos;
Why Casting is Necessary:Java performs integer division by default when both operands are integers. Without casting:
// Without cast: Integer division (incorrect)
int result = 57 / 14;  // Result: 4 (truncated)

// With cast: Floating-point division (correct)
double result = (double) 57 / 14;  // Result: 4.071428...
How It Works:
  • (double) sumaTotal converts the integer sum to a double
  • Division then operates in floating-point arithmetic
  • Result is stored in promedio variable with full precision
Note: Due to the bug on line 25, this average is calculated incorrectly.

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Output Formatting

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Average Output (Line 36)

Displays the average with exactly 2 decimal places:
Main.java:36
System.out.printf("El promedio es: %.2f", promedio);
Format String Breakdown:
  • %: Marks the start of a format specifier
  • .2: Specifies 2 decimal places of precision
  • f: Indicates floating-point number format
Examples:
ValueOutput
4.071428”El promedio es: 4.07”
22.5”El promedio es: 22.50”
10.0”El promedio es: 10.00”
7.999”El promedio es: 8.00” (rounded)

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Difference Array Output (Lines 38-41)

Displays all elements of the difference array:
Main.java:38-41
System.out.println("\nArreglo de diferencias");
for (int i = 0; i < arrayDiferencia.length; i++) {
    System.out.println("Posición" + i + ":" + arrayDiferencia[i]);
}
Features:
  • Line 38: Prints header with newline escape sequence (\n)
  • Lines 39-41: Iterates through all 7 elements
  • Displays position (index) and corresponding difference value
Sample Output:
El promedio es: 15.50
Arreglo de diferencias
Posición0:5
Posición1:7
Posición2:8
Posición3:-2
Posición4:5
Posición5:-2
Posición6:7
Note: The output format lacks spacing (e.g., “Posición0:5” instead of “Posición 0: 5”).

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Operation Summary

Input Operations

Two sequential loops collect 7 integers each from user input

Difference Calculation

Element-wise subtraction: array1[i] - array2[i]

Average Calculation

Sum divided by total elements (14) with double precision

Formatted Output

Printf for average (2 decimals), loop for difference array

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Performance Characteristics

OperationTime ComplexitySpace Complexity
First array inputO(n) where n=7O(1) auxiliary
Second array inputO(n) where n=7O(1) auxiliary
Difference calculationO(n) where n=7O(1) auxiliary
Average calculationO(1)O(1)
Output displayO(n) where n=7O(1) auxiliary
TotalO(n)O(n) for arrays

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See Also

  • Main Class - Complete class structure and variable declarations
  • Input Format - Understanding input requirements (includes bug documentation)
  • Output Format - Understanding program output

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