Arrays3.java

import java.io.*;
import java.util.*;

public class Arrays3{
    private int[] a;
    private Random r = new Random();
    public ArrayStuff() {
        a=new int[20];
	for (int i=0;i<a.length;i++) {
	    a[i]=r.nextInt(100);
	}
    }
    
    public ArrayStuff(int s) {
	a=new int[s];
	for (int i=0;i<a.length;i++) {
	    a[i]=r.nextInt(100);
	}
    }
    public ArrayStuff(int s,int max) {
        a=new int[s];
        for (int i=0;i<a.length;i++) {
            a[i]=r.nextInt(max);
        }
    }
    public String toString() {
        return Arrays.toString(a);
    }

    // return the index of the max element
    public int findMaxIndex() {
        if (a==null || a.length==0) 
            return -1;

	int maxi = 0;
        for (int i=0;i<a.length;i++) {
            if (a[i] > a[maxi])
                maxi = i;
        }
        return maxi;
    }

    public int get(int n) {
        if (n>=0 && n < a.length) 
            return a[n];
        else
            return -1;
    }
    public int find(int n) {
        for (int i=0;i<a.length;i++) {
            if (a[i]==n)
                return i;
        }
        return -1;
    }

    public int freq(int n) {
        int appearances = 0;
        for (int i=0;i<a.length;i++){
            if (a[i]==n)
                appearances = appearances + 1;
        }
        return appearances;
    }

    public void mode() {
        int maxIndex = 0;
        int maxFreq=freq(a[0]);
        for (int i=0;i<a.length;i++){
            if (freq(a[i])>maxFreq) {
                maxFreq=freq(a[i]);
                maxIndex = i;
            }
        }
        System.out.println("Mode: "+a[maxIndex]+" Count: "+maxFreq);
    }
 
    //////////
    public double mean() {
	double n = 0;
	for (i = 0; i <  a.length; i++) {
	    n = n + a [i]; 
	}
	n = n / a.length;
	return n;
    }

    public double stddev() {
	double n = a.mean();
	for (i = 0; i <  a.length; i++) {
	    a[i] = Math.pow((a[i] - n),2); 
	}
	n = a.mean();
	n = Math.sqrt(n);
	return n;
    }


}