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  1. #1
    dalonehunter is offline Member
    Join Date
    Oct 2009
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    Default Need help with counting strings in an array.

    Hey guys, as you'll see I'm kind of new to Java so I don't know too much and I came across this site looking for help. I'm making a program for my java class and the first part of the assignment is to make it take grades from a teacher and then count the number of each grade. For example, it would count 4 A's, 3 B's, 1 C, etc... The problem I have is counting the number of each letter grade in the array. This is what I have so far:
    Java Code:
    import javax.swing.JOptionPane;
    public class Grading {
    	public static void main(String[] args) {
    		int a;
    		a=Integer.parseInt(JOptionPane.showInputDialog("How many students are in your class?"));
    		String grades[]=new String[a];
    		for(int i=0;i<grades.length;i++)
    		{grades[i]=JOptionPane.showInputDialog("What are their grades?");
    So I have the person enter the number of students and than enter that many grades into an array and that works fine. The problem is counting the number of each grade. I tried using some If, else statements but to no avail. Can you guys help a noobie out? Thanks.

  2. #2
    r035198x is offline Senior Member
    Join Date
    Aug 2009
    Rep Power


    You can count letter frequencies using a Map<String, Integer>.
    You loop through the array, if the letter is in the array (Integer count = Map.get(letter)) increment it's count and set that in the map Map.put(letter, newCount). Otherwise add the letter to the map with a count of 1.

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