Question

Program Overview This brief exercise is designed for you to consider how reference variables behave when you are passing them as arguments by-value. Instructions Name your class References.java. 1. Implement the following methods. 1.1 Method name: readStudentNames Purpose: This method accepts an array of strings as a parameter. It loops through the array and asks the user to input names. It populates the array of strings with the names. Parameters: an array of Strings, stringArray Return type: void In the body of the method: . • Put in a println telling the user that you are using the stringArray parameter Loop through the entire array o Prompt the user to enter a name and use your counter. o Read a name and assign it to the current element of the array. Use index i.

Answer 1

// References.java

import java.util.Scanner;

public class References {

/**
   * method that accepts an array of strings as a parameter. It loops through the array
   * and asks the user to input names. It populates the array of strings with the names.
   * @param stringArray, an array of Strings
   */
   public static void readStudentNames(String[] stringArray)
   {
       Scanner keyboard = new Scanner(System.in);
       System.out.println("readStudentNames Method: Putting values inside stringArray parameter");
       // loop over the array, accepting strings for each array element
       for(int i=0;i<stringArray.length;i++)
       {
           System.out.print("Enter name "+(i+1)+": ");
           stringArray[i] = keyboard.nextLine();
       }
   }
  
   /**
   * method that accepts an ArrayList of strings as a parameter. It loops through the ArrayList
   * and asks the user to input names. It populates the ArrayList with the names.
   * @param stringArray, an ArrayList of Strings
   */
   public static void readStudentNames(ArrayList<String> stringList)
   {
       Scanner keyboard = new Scanner(System.in);
       System.out.println("readStudentNames Method: Putting values inside stringList parameter");
       // loop 5 times, to input 5 names into the array list
       for(int i=0;i<5;i++)
       {
           System.out.print("Enter name "+(i+1)+": ");
           stringList.add(keyboard.nextLine());
       }
   }
  
   public static void main(String[] args) {
  
       System.out.println("\t****** Passing References - Reading 5 Names *******");
       System.out.println("\nMain Method: Passing an Array, nameArray, by-value");
       String[] nameArray = new String[5];
       readStudentNames(nameArray);
       System.out.println("\nMain Method: The contents of nameArray are:");
       for(int i=0;i<nameArray.length;i++)
           System.out.println(nameArray[i]);
      
       System.out.println("\nMain Method: Passing an ArrayList, nameArrayList, by-value");
       ArrayList<String> nameArrayList = new ArrayList<String>();
       readStudentNames(nameArrayList);
       System.out.println("\nMain Method: The contents of nameArray are:");
       for(String name : nameArrayList)
           System.out.println(name);
   }  
}

// end of References.java

Output:

Answer 2

// References.java

import java.util.Scanner;

public class References {

/**
   * method that accepts an array of strings as a parameter. It loops through the array
   * and asks the user to input names. It populates the array of strings with the names.
   * @param stringArray, an array of Strings
   */
   public static void readStudentNames(String[] stringArray)
   {
       Scanner keyboard = new Scanner(System.in);
       System.out.println("readStudentNames Method: Putting values inside stringArray parameter");
       // loop over the array, accepting strings for each array element
       for(int i=0;i<stringArray.length;i++)
       {
           System.out.print("Enter name "+(i+1)+": ");
           stringArray[i] = keyboard.nextLine();
       }
   }
  
   /**
   * method that accepts an ArrayList of strings as a parameter. It loops through the ArrayList
   * and asks the user to input names. It populates the ArrayList with the names.
   * @param stringArray, an ArrayList of Strings
   */
   public static void readStudentNames(ArrayList<String> stringList)
   {
       Scanner keyboard = new Scanner(System.in);
       System.out.println("readStudentNames Method: Putting values inside stringList parameter");
       // loop 5 times, to input 5 names into the array list
       for(int i=0;i<5;i++)
       {
           System.out.print("Enter name "+(i+1)+": ");
           stringList.add(keyboard.nextLine());
       }
   }
  
   public static void main(String[] args) {
  
       System.out.println("\t****** Passing References - Reading 5 Names *******");
       System.out.println("\nMain Method: Passing an Array, nameArray, by-value");
       String[] nameArray = new String[5];
       readStudentNames(nameArray);
       System.out.println("\nMain Method: The contents of nameArray are:");
       for(int i=0;i<nameArray.length;i++)
           System.out.println(nameArray[i]);
      
       System.out.println("\nMain Method: Passing an ArrayList, nameArrayList, by-value");
       ArrayList<String> nameArrayList = new ArrayList<String>();
       readStudentNames(nameArrayList);
       System.out.println("\nMain Method: The contents of nameArray are:");
       for(String name : nameArrayList)
           System.out.println(name);
   }  
}

// end of References.java

Output:

****** Passing References - Reading 5 Names ******* Main Method: Passing an Array, nameArray, by-value readStudentNames Method: Putting values inside stringArray parameter Enter name 1: Balin Enter name 2: Bilbo Enter name 3: Pippin Enter name 4: Merry Enter name 5: Samwise Main Method: The contents of nameArray are: Balin Bilbo Pippin Merry Samwise Main Method: Passing an ArrayList, nameArrayList, by-value readStudentNames Method: Putting values inside stringList parameter Enter name 1: Odo Enter name 2: Worf Enter name 3: Jadzia Enter name 4: Kira Enter name 5: Ezri Main Method: The contents of nameArray are: Odo Worf Jadzia Kira Ezri