Problem

Today we'll look at returning a new array from a different method.

Let's now expand on the printArray program created in the previous problem. Recall you created a method to print the names of students stored in different arrays for different classes. You now have been given an additional class to teach, COMP2040, and must input a new list of students for this class. To do this, you will need to create an additional method in the existing program.

Take the sample solution from printArray below and add a fillArray method to it. This method should accept a number as an integer as input, representing the number of students in the class, and return an array of Strings, containing the students names, as output. You will need some method of taking user input within this method.

 public class PrintArray{
	public static void main (String [] args){
		String [] comp1010 = { "Adam", "Bob", "Carl", "David", "Edward"};
		String [] comp1020 = { "Amy", "Beth", "Cindy", "Dawn", "Ellen"};
		String [] comp1260 = { "Mike", "Mary", "Matthew", "Megan", "Moe"};

		System.out.println("COMP 1010:");
		printArray(comp1010);
		System.out.println("COMP 1020:");
		printArray(comp1020);				
		System.out.println("COMP 1260:");
		printArray(comp1260);				

		System.out.println("--End of Processing--");
	}

	public static void printArray(String [] courseList){

		for (int i=0; i<courseList.length;i++){	
			System.out.println(courseList[i]);
		}
		System.out.println();	
	}
} 

...By Students

"Using methods with arrays is just the beginning of the myriad ways in which methods will assist you in future programming. I remember when I first began learning about methods, they seemed like a complete waste of time. I mean, why section off this small bit of code instead of just putting the couple of lines in the main? All I can say is learn this stuff well, because I couldn't have been more wrong. Methods are the building blocks that you will used for everything else you do in programming."

Solution

To create the fillArray method, first create a new array in the new method. Then use a for loop to cycle through the entire array. Inside the loop it should prompt the user to enter a name, and insert the user input into the array.

Code

Solution Code

import javax.swing.*;

class Students{
	public static void main (String [] args){

		String [] comp1010 = fillArray(10);
		printArray(comp1010);


		System.out.println("--End of Processing--");
	}

	public static void printArray(String [] courseList){	//note that the method is void, and the input variable is an array of Strings
								//We called the array "courseList", since this can refer to any of the arrays
								//we send it

		for (int i=0; i<courseList.length;i++){		//for loop to go through each element in the array
			System.out.println(courseList[i]);	//print the current element
		}
		System.out.println();				//add a blank line after the list of students
	}

	public static String[] fillArray(int size){
	        String[] names = new String[size];                                         //an Array to hold the entered names
		
                for (int i=0;i<names.length;i++){
			names[i] = JOptionPane.showInputDialog(null, "Please enter a name:");//insert the user input name into the array
		}
		return names;
	}
}