Answer to Question #188617 in Java | JSP | JSF for Abdul Hadi

Question

Create a Java Project With Your name as “YourNameProjectQNo1”, add a class to this Project, Class name should be Your Name with Your Reg No as “YourNameYourRegNo”

a. Add a Method to Accept names and marks of n students from user, enter the value of n from User

b. Ensure that valid data is entered. If user enters an invalid data, then appropriate message should be displayed using Message Dialog Box e.g. ‘Name cannot be a number’ or ‘Marks must be an integer value’

c. Add another Method, to Display this data in descending order according to marks such that name of student.  

Answer 1

import javax.swing.JOptionPane;


public class Q188617 {


	/**
	 * The start point of the program
	 * 
	 * @param args
	 */
	public static void main(String[] args) {
		String names[];
		int marks[];
		String nStr = " ";
		while (!isInteger(nStr)) {
			nStr = JOptionPane.showInputDialog("Enter N: ");
			if (!isInteger(nStr)) {
				JOptionPane.showMessageDialog(null, "N must be an integer value");
			}
		}
		int n = Integer.parseInt(nStr);
		names = new String[n];
		marks = new int[n];
		AddStudents(names, marks);
		DisplayDescendingOrder(names, marks);
	}


	/**
	 * a Method to Accept names and marks of n students from user, enter the value
	 * of n from User
	 * 
	 * @param names
	 * @param marks
	 */
	private static void AddStudents(String names[], int marks[]) {
		for (int i = 0; i < names.length; i++) {
			String name = " ";
			while (!isString(name)) {
				name = JOptionPane.showInputDialog("Enter student name " + (i + 1) + ": ");
				if (!isString(name)) {
					JOptionPane.showMessageDialog(null, "Name cannot be a number.");
				}
			}
			names[i] = name;
			String markStr = " ";
			while (!isInteger(markStr)) {
				markStr = JOptionPane.showInputDialog("Enter student mark " + (i + 1) + ": ");
				if (!isInteger(markStr)) {
					JOptionPane.showMessageDialog(null, "Marks must be an integer value");
				}
			}
			marks[i] = Integer.parseInt(markStr);
		}
	}


	/***
	 * Method, to Display this data in descending order according to marks such that
	 * name of student.
	 * 
	 * @param names
	 * @param marks
	 */
	private static void DisplayDescendingOrder(String names[], int marks[]) {
		int n = marks.length;
		int temp = 0;
		for (int i = 0; i < n; i++) {
			for (int j = 1; j < (n - i); j++) {
				if (marks[j - 1] < marks[j]) {
					// swap marks
					temp = marks[j - 1];
					marks[j - 1] = marks[j];
					marks[j] = temp;
					
					// swap names
					String tempName = names[j - 1];
					names[j - 1] = names[j];
					names[j] = tempName;
				}
			}
		}
		String output= String.format("%-20s%-20s\n","Names","Marks");
		for (int i = 0; i < n; i++) {
			output+= String.format("%-25s%-20d\n",names[i],marks[i]);
		}
		JOptionPane.showMessageDialog(null, output);
	}


	private static boolean isString(String s) {
		for (int i = 0; i < s.length(); i++) {
			if (!Character.isAlphabetic(s.charAt(i))) {
				return false;
			}
		}
		return true;
	}


	private static boolean isInteger(String s) {
		for (int i = 0; i < s.length(); i++) {
			if (!Character.isDigit(s.charAt(i))) {
				return false;
			}
		}
		return true;
	}
}