Question

Below is my code and the instructions for the code. I can't figure out what's wrong. Please help.

Tasks

This lab has two parts:

1. Writing a searching function for 1D arrays.
2. Writing a simple class.

Part 1 – Searching

Continuing with arrays, we will now expect you to find information in an array and derive useful properties from the information stored in an array.

1. Start Eclipse.

2. Change the workspace directory location to something "safe". You may want to temporarily choose the Desktop and then save the file to something permanent once you're done (e.g. a network drive or flash drive).

3. Go to the File menu and select New Java Project. Call it YOURNAME_Lab1BArray.

4. Create a main method, and create a 2D integer array called data, with a size of five (5) by five (5). Ask the user to input the values for this array (Scanner’s nextInt).

5. Create a method called LongestPositiveSeries, that takes in a 2D array and finds the length of the longest continuous series of positive numbers in it.
   • For example, if we had an array like this:

0	1	2	3	4
5	-1	-5	-5	5
3	-2	56	25	-15
0	5	5	0	324
46	25	0	0	0

• The length would be 5. For this problem, 0 is considered non-negative and not positive, so we start counting from index [0, 1] (which is 1) to [1, 0] (which is 5) and end at index [1, 1] (which is –1).

• Hint: Consider using a basic linear search and modifying it to keep track of the current positive streak of numbers.

6. Call that method in your main, for the array data.

7. Print out the returned result from your method in your main, along with the content of data.

CODE BELOW:

import java.util.Scanner;

public class AssignmentOne {

public static void main(String[] args) {

Scanner scan = new Scanner(System.in);

int[][] data = new int[5][5];

//setting values into the array;

System.out.println("Enter values for the array: ");

for (int row = 0; row < data.length; row++) {

for (int column = 0; column < data[0].length; column++) {

data[row][column] = scan.nextInt();

}

}

//printing array to screen

for (int row = 0; row < data.length; row++) {

for (int column = 0; column < data[row].length; column++) {

System.out.print(data[row][column] + " ");

}

System.out.println();

}

//calling the array;

int longestStreak = LongestPositiveSeries(data);

System.out.println("Longest positive streak: " + longestStreak);

//closing scanner;

scan.close();

}

public static int LongestPositiveSeries(int[][]myArray) {

int[][] array = new int[5][5];

int positiveStreak = 0;

int longestPosStreak = 0;

for (int row = 0; row < array.length; row++) {

for (int column = 0; column < array[0].length; column++) {

if (array[row][column] > 0) {

positiveStreak++;

//longestPosStreak++;

}

else {

if (longestPosStreak < positiveStreak) {

longestPosStreak = positiveStreak;

positiveStreak = 0;

}

positiveStreak = 0;

}

}

}

return longestPosStreak;

}

}

Answer 1

I saw your code and found that you were creating a new array ( whose name was array) inside the LongestPositiveSeries function. So this was wrong, you don't need to create a new array inside the LongestPositiveSeries function.
Instead, you need to use the myArray (which has come as a parameter to the LongestPositiveSeries function) inside the for loop. You were creating and then using array inside the for loop, but in the corrected code I have used myArray inside for loop and commented on the statement where you were creating the array.

myArray contains the data entered by the user, you passed data array to the LongestPositiveSeries function and myArray is the receiving parameter, so it is obvious that you need to use myArray inside for loop and not array.

Corrected code:

import java.util.Scanner;

public class AssignmentOne {

   public static void main(String[] args) {

       Scanner scan = new Scanner(System.in);

       int[][] data = new int[5][5];

       // setting values into the array;

       System.out.println("Enter values for the array: ");

       for (int row = 0; row < data.length; row++) {

           for (int column = 0; column < data[0].length; column++) {

               data[row][column] = scan.nextInt();

           }

       }

       // printing array to screen

       for (int row = 0; row < data.length; row++) {

           for (int column = 0; column < data[row].length; column++) {

               System.out.print(data[row][column] + " ");

           }

           System.out.println();

       }

       // calling the array;

       int longestStreak = LongestPositiveSeries(data);

       System.out.println("Longest positive streak: " + longestStreak);

       // closing scanner;

       scan.close();

   }

   public static int LongestPositiveSeries(int[][] myArray) {

       // no need to use the below statement
       // int[][] array = new int[5][5];

       int positiveStreak = 0;

       int longestPosStreak = 0;

       // use myArray inside the for loop
       for (int row = 0; row < myArray.length; row++) {

           for (int column = 0; column < myArray[0].length; column++) {

               if (myArray[row][column] > 0) {

                   positiveStreak++;

                   // longestPosStreak++;

               }

               else {

                   if (longestPosStreak < positiveStreak) {

                       longestPosStreak = positiveStreak;

                       positiveStreak = 0;

                   }

                   positiveStreak = 0;

               }

           }

       }

       return longestPosStreak;

   }

}

Note: Please refer to the screenshot of the corrected code to understand the indentation of the code.

Screenshot of the corrected code:

Output and Input: