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9.0

Quick Sort Beginner Java

Asked by elliottbenzle in Java Programming Language, New to Java Programming

Tags: quick sort, java

Hi all,
 I'm working on a Java program that will:

1) Take user input for a file name with numers
2) Read numbers into an array
3) Apply the quickSort/partition methods to the array
4) And print to the screen the sorted array

Much thanks to anyone that can help me get this program working right, Thanks

-Kyle
This is my current output:

Name of file with array: text.txt
Exception in thread "main" java.lang.StackOverflowError
      at ss.quickSort(ss.java:62)
      at ss.quickSort(ss.java:66)
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import java.io.*;
import java.io.File;
import java.util.Scanner; 
public class ss {
	public static void main(String[] args) throws IOException {
		System.out.print("Name of file with array: ");
		Scanner readIn = new Scanner(System.in);
		String input = readIn.nextLine();
		testScan1(input);
		
	} 
	public static void testScan1(String filename) {
		File file = new File(filename);
		Scanner scan;
		int[] array;
		try {
			array = new int[5];
			scan = new Scanner(file);
		} catch (java.io.FileNotFoundException e) {
			System.out.println("couldn't open. file not found ");
			return;
		}
		int i =0;
		while (scan.hasNext()) {
			//for (i = 0; i <= file.length(); ++i) 
				array[i] = Integer.parseInt(scan.next());
				i++;}
				quickSort(array, 0, array.length-1);
			partition(array, 0, array.length-1);
			
				//System.out.println(java.util.Arrays.toString(array));
				for (int j = 0; j < array.length; ++j)
				System.out.println(array[i] + " ");
			}
		
	 
	static int partition(int[] arr, int left, int right) {
		int i = left;
		int j = right;
		int tmp;
		int pivot = arr.length-1;
		while (i <= j) {
			while (arr[i] < pivot)
				i++;
			while (arr[j] > pivot)
				j--;
			if (i <= j) {
				tmp = arr[i];
				arr[i] = arr[j];
				arr[j] = tmp;
				i++;
				j--;
			}
		}
		return i;
	} 
	static void quickSort(int[] arr, int left, int right) {
		int index = partition(arr, left, right);
		if (left < (index - 1)); {
			
		}
		quickSort(arr, left, index - 1);
		if (index < right) {
			quickSort(arr, index, right); 
		}
	}		
	//for (int j = 0; j < array.length; ++j)
	//	System.out.println(array[i] + " ");
}
[+][-]11/05/09 05:51 PM, ID: 25756055Expert Comment

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[+][-]11/05/09 06:05 PM, ID: 25756096Author Comment

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[+][-]11/05/09 06:07 PM, ID: 25756101Expert Comment

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[+][-]11/11/09 03:39 AM, ID: 25794177Accepted Solution

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About this solution

Zones: Java Programming Language, New to Java Programming
Tags: quick sort, java
Sign Up Now!
Solution Provided By: dincaflorin
Participating Experts: 3
Solution Grade: A
 
 
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