Write some JAVA for me please, not working the way I wanted it too...

Question

Here's what I am getting when I go to run it:
C:\Documents and Settings\Brad.HOME\Desktop\FINAL>java project1
Usage: project1 [Array File Path]
C:\Documents and Settings\Brad.HOME\Desktop\FINAL>
What I need is for it to ask me to enter the location of the numbers file and then calculate the Max, Min, Mean, etc off of that file I enter in. Right now it just says:
Usage: project1 [Array File Path]
-------------------------------java below-------------------------------------------------
import java.io.*;
public class project1 {
* Array File Path
private String location;
* set Location
* @param location String
public void setLocation(String location) {
this.location = location;
* Program initialization
public project1() {
int ar[] = new int[50];
ReadFile(location, ar);
sort(ar);
System.out.println("Minimum= " + ar[0]);
System.out.println("Maximum=" + ar[ar.length - 1]);
System.out.println("Mean= " + mean(ar));
System.out.println("Mode= " + modal(ar));
System.out.println("Median= " + median(ar));
System.out.println("Std Dev= " + stdDev(ar));
* Main program
* @param args String[]
public static void main(String args[]) {
if (args.length == 1) {
new project1().setLocation(args[0]);
else {
System.out.println("Usage: project1 [Array File Path]");
* Calculate the mean
* @param ar int[]
* @return double
public double mean(int ar[]) {
int sum = 0;
for (int i = 0; i < ar.length; i++) {
sum += ar;
return (sum / ar.length);
* Calculate the mode/modal
* @param a int[]
* @return int
public int modal(int a[]) {
int n;
int freq = 0;
int Mfreq = 0;
int Mn = a[0];
for (int i = 0; i < a.length; i++) {
n = a[i];
for (int j = 0; j < a.length; j++) {
     if (a[j] == n) {
     freq++;
if (freq > Mfreq) {
     Mn = n;
return Mn;
* Calculate the median
* @param a int[]
* @return int
public int median(int a[]) {
if (a.length % 2 == 0) {
int x = a[a.length / 2];
int y = a[ (a.length + 2) / 2];
return (x + y) / 2;
else {
return a[ (a.length + 1) / 2];
* Calculate Standard Deviation
* @param a int[]
* @return double
public double stdDev(int a[]) {
int s2 = 0;
int s = 0;
for (int i = 0; i < a.length; i++) {
s2 += (a[i] * a[i]);
s += a[i];
return Math.sqrt( (s2 - (s * 2) / a.length) / (a.length - 1));
* Sort integer array
* @param a int[]
public void sort(int a[]) {
int tmp;
for (int i = 0; i < a.length; i++) {
for (int j = 0; j < a.length; j++) {
     if (a[j] > a[j + 1]) {
     tmp = a[j];
     a[j] = a[j + 1];
     a[j + 1] = tmp;
* Read integer array from specified file
* @param filename String
* @param ar int[]
* @return int
public int ReadFile(String filename, int ar[]) {
File infile = new File(filename);
int value, n = 0;
try {
BufferedReader reader = new BufferedReader(new FileReader(infile));
String line = null;
while ( (line = reader.readLine()) != null) {
     value = Integer.parseInt(line);
     ar[n++] = value;
return n;
catch (IOException e) {
System.err.println("Problem reading input file!");
System.exit(1);
return n;

Answer 1

Please use code tags when posting code. There is a
button labeled code right above the text box
where you type in your post.
Your first problem occurs herepublic static
void main(String args[]) {
if (args.length == 1) {
new project1().setLocation(args[0]);
else {
System.out.println("Usage: project1 [Array File
y File Path]");
}This code executes when you first launch the
application. It checks to see if there were any
arguments in the comman line. If the number of
arguments is not equal to 1, then you get the Usage
output. You must launch the program with one
argument.I tried java project1 C:\\Temp.txt, but it still ends up with a NullException handler. I edited the code and added a catch for it so it returns File doesn't exist, but I swear it does and I'm pointing to it correctly...