Examples w/Arrays

 

Ex1

 

//grades data entry

import java.util.Scanner;

 

public class gradesDataEntry

{

    private static char assignLetterGrade (double grade)

    {

              if(grade >= 90)

              return 'A';

            if(grade >= 80)

                  return 'B';

              if(grade >= 70)

              return 'C';

           if(grade >= 60)

                  return 'D';

              return 'F';

      }

 

    public static void main (String[] args){

          double [] grade = new double [3];

      String [] name = new String [3];

            char [] letterGrade = new char [3];

   

      Scanner kb = new Scanner (System.in);

   

            int j = 0;

            double av, sum = 0;  

            String t;

            int selection;

           

            do

            {

                  System.out.print ("Enter selection (1-data entry 2-list 3-letter grades 4-average 5-exit) ");

                  selection = kb.nextInt();                

           

                  if (selection == 1){

                        if(j >= 3)

                              System.out.println ("Array full!!!");

                        else{

                              System.out.print ("Enter name: ");

                              name[j] = kb.next();

                             

                              System.out.print ("Enter grade: ");

                        grade[j] = kb.nextDouble();

                             

                              j = j + 1;

                        }

                  }

 

                  else if(selection == 2){

                for (int i=0; i<j; i++){

                        t = (i+1) + " " + name[i] + "\t" + grade[i];

                        System.out.print (t + "\n");

                  }

            }

 

              else if (selection == 3){

                  for (int i = 0; i<j; i++)

                        letterGrade[i] = assignLetterGrade (grade[i]);

                 

                  for (int i=0; i<j; i++){

                        t = (i+1) + " " + name[i] + "\t" + grade[i] + "\t" + letterGrade[i];

                        System.out.print (t + "\n");

                  }

            }

       

            else if (selection == 4){

                  for (int i=0; i<j; i++){

                        sum = sum + grade[i];

                  }

                  av = sum/j;

                  System.out.println("\nOverall average is "+av);

            }

           

            }while (selection != 5);

    }

}

 

Ex2

 

import java.util.Scanner;

 

public class PrimeNumbersArray

{

      private static boolean isPrime(int number){

            if (number == 1)

                  return false;

            for(int i=2; i < number/2+1; i++)

                  if(number%i == 0)

                        return false;

            return true;

      }

     

    public static void main (String[] args)

    {

          int number;

 

            Scanner keyboard = new Scanner (System.in);

           

            System.out.print ("Enter number: ");

            number = keyboard.nextInt ();

           

            int [] primeArray = new int [number];

          int test = 2;

     

      for(int i=0; i < primeArray.length; i++){

                  while (!isPrime (test))

                        test++;

                  primeArray [i] = test;

                  test++;

            }

           

      for(int i=0; i < primeArray.length; i++){

                  System.out.print (primeArray [i] + " ");

            }

 

            System.out.println();

    }

}

 

Ex3

 

//sorts random filled array using sort method

 

import java.util.Scanner;

 

public class SortMethod

{

     

      public static void sort (int [] arr){

          int temp;

 

          for (int i=0; i < arr.length-1; i++){

                for (int j = i+1; j < arr.length; j++){

               if(arr [j] < arr [i]){

                      temp = arr [j];

                        arr [j] = arr [i];

                        arr [i] = temp;

                  }

           }

            }

      }

 

    public static void main (String[] args)

    {

        Scanner keyboard = new Scanner (System.in);

        int limit;

 

        System.out.print ("Enter limit: ");

 

        limit = keyboard.nextInt ();

 

        int[] array = new int[limit];

 

        for (int i=0; i <= array.length - 1; i++)

            array [i] = (int)(Math.random()*100 + 1);

 

        System.out.print ("\n\nOriginal Array\n");

 

          for (int i=0; i <= array.length-1; i++)

                System.out.print (array[i] + " ");

           

            sort (array);

           

                 

        System.out.print ("\n\nSorted Array\n");

 

        for (int i=0; i <= array.length - 1; i++)

            System.out.print (array [i] + " ");

 

    }

}

 

Ex4

 

public class Student

{

      final int YEAR = 2007;

     

      private String name;

      private int qualityPoints;

      private int credits;

      private int birthYear;

 

      public Student(String name, int birthYear)

      {

            this.name = name;

            this.birthYear = birthYear;

      }

     

      public Student(String name, int qualityPoints, int credits, int birthYear)

      {

            this.name = name;

            setMarks (qualityPoints, credits);

            setYear (birthYear);

      }

     

      public void setMarks (int qualityPoints, int credits)

      {

            this.qualityPoints = qualityPoints;

            this.credits = credits;

      }

     

      public void setYear (int birthYear)

      {

            this.birthYear = birthYear;

      }

     

      public String getName ()

      {

            return name;

      }

 

      public int getCredit ()

      {

            return credits;

      }

 

      public String toString ()

      {

            return (name + "\t" + birthYear);

      }

     

      public int getAge ( )

      {

            return YEAR - birthYear;

      }

}

 

 

import java.util.Scanner;

 

public class TestStudent

{

 

      public static void main (String[] args)

      {

            Student s1, s2, s3;

           

            s1 = new Student ("Mehmet", 1988);

            s2 = new Student ("Sibel", 1989);

            s3 = new Student ("Arda", 1991);

           

            Student [] stArray = new Student [3];

           

            stArray [0] = s1;

            stArray [1] = s2;

            stArray [2] = s3;

           

            for (int i = 0; i < stArray.length; i++)

                  System.out.println (stArray[i] + "\t" + stArray[i].getAge ());

 

      }

     

}

 

Ex5

 

import java.util.Scanner;

 

public class ReturnArray

{

    private static void initialize (int []a)

    {

        for (int i=0;i<=a.length-1;i++){

            a[i]=(int)(Math.random()*100);

        }

    }

 

    private static double [] divide (int [] a)

    {

      double [] d = new double[a.length];

     

        int i=0;

        while (i <= a.length-1){

            d[i] = a[i] / 10.0;

            i++;

        }

        return d;

    }

 

    public static void main (String[] args)

    {

      Scanner keyboard = new Scanner (System.in);

          int n;

         

        System.out.print ("Enter N: ");

        n = keyboard.nextInt ();

 

        int [] p = new int[n];

        double [] x = new double[n];

       

        initialize(p);

       

        x = divide(p);

 

        for (int i = 0; i <= p.length-1; i++){

            System.out.println (p[i] + "\t" + x[i] + "\n");

        }

     

    }

}