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Thread: Bubble Sort help

  1. #1
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    Default Bubble Sort help

    I have to creat a bubble sort program for homework in my programming 1 class. My requirements are to write a program that allows the user to enter in the number of students, the students name, and the students test score. The output will be the students name and matching score in decreasing order. It says I must use an array, a method, and a bubble sort. I will attach the code that I have written. I keep getting two errors; one being a ']' expected and the other being an illegal start of expression error. I have tried changing tons of stuff within the code but I am too inexperienced to come up with the solution. Can someone please help me? Attached is the code I have written and what cmd is giving me when I try to compile the code.
    Attached Files Attached Files


  2. #2
    Administrator copeg's Avatar
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    Default Re: Bubble Sort help

    Please post the code directly to the forums (and please use the code tags), preferentially as an SSCCE. I and many others will not try an download the attachments to view your code. The errors you mention sound like compile time errors, probably have an extra/missing a bracket, semicolon, or any number of things that could be a syntax error.

  3. #3
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    Default Re: Bubble Sort help

    mport java.util.Scanner;
    public class Homework5{
    public static void main(String[] args){
    Scanner input= new Scanner(System.in);
     
    	System.out.println("Enter number of students: ");
     
    	int numberofstudents=input.nextInt();
     
    	double[] myList= new Double [num];
     
    	System.out.println("Enter " + myList.length + " Values");
     
    	for(int i=0; i < myList.length; i++){
     
    	myList[i]=input.nextDouble();
     
    	System.out.println("Enter student's name: ");
     
    	String[] studentsname= new String [num];
     
    	students name [i] = input.next();
     
    	System.out.println("Enter student's score: ");
     
    	double studentsscore=input.nextDouble();
     
    	String[] studentScores= new String [num];
     
    	}
     
    	int i;
     
    	int array[]= {i};
     
    	System.out.println("Values before the sort");
     
      for(i = 0; i < array.length; i++)
     
    	System.out.print( array[i]+" ");
     
    	System.out.println();
     
    	bubble_sort(array, array.length);
     
    	System.out.println("Values after the sort");
     
    	for(i = 0; i < array.length; i++)
     
    	System.out.print(array[i]+" ");
     
    	System.out.println();
     
    	}
     
    	public static void bubble_sort( int a[], int n ){
     
    	int i, j, t=0;
     
    	for(i = 0; i < n; i++){
     
    		for(j = 1; j < (n-i); j++){
     
    		if(a[j-1] > a[j]){
     
    		t = a[j-1];
     
    		a[j-1]=a[j];
     
    		a[j]=t;
    		}
    	}
    	}
    	}
    }
    Last edited by helloworld922; June 5th, 2011 at 02:22 AM.

  4. #4
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    Default Re: Bubble Sort help

    Does anyone have any idea what is wrong with my code? I stayed up till 1:30am last night searching on the internet and looking in my school book and I just can't figure the problem out. Please help!

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    Default Re: Bubble Sort help

    You need to define methods and place your code withing that/those methods...
    See Defining Methods (The Java™ Tutorials > Learning the Java Language > Classes and Objects)

  6. #6
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    Default Re: Bubble Sort help

    Ok when I compile my program now it is giving me 8 errors within the [B]public static void bubble_sort( int a[], int n){ line. I am confused as to why this is doing this. All the errors are illegal start of expression or ';' expected. This is the exact line my teacher gave me. She said this would work. Help please! Here is my full code:

    import java.util.Scanner;
    public class Homework5{
    public static void main(String[] args){
    Scanner input= new Scanner(System.in);
     
      System.out.println("Enter number of students: ");
     
    	int numberofstudents=input.nextInt();
     
    	double[] myList= new Double [num];
     
    	System.out.println("Enter " + myList.length + " Values");
     
    	for(int i=0; i < myList.length; i++){
     
    	myList[i]=input.nextDouble();
     
    	System.out.println("Enter student's name: ");
     
    	String[] studentsname = new String [num];
     
    	studentsname [i] = input.next();
     
    	System.out.println("Enter student's score: ");
     
    	String[] studentsscore = new String [num];
     
    	studentsscore [i] = input.next();
     
    	double[] myList= new double [num];
     
    	System.out.println("Enter " + myList.length + " Values");
     
    	for(int i=0; i < myList.length; i++){
     
    	myList[i]=input.nextDouble();
     
    	}
     
    	int i;
     
    	int array[]= {i};
     
    	System.out.println("Values before the sort");
     
      for(i = 0; i < array.length; i++)
     
    	System.out.print( array[i]+" ");
     
    	System.out.println();
     
    	bubble_sort(array, array.length);
     
    	System.out.println("Values after the sort");
     
    	for(i = 0; i < array.length; i++)
     
    	System.out.print(array[i]+" ");
     
    	System.out.println();
     
    	}
     
    	public static void bubble_sort( int a[], int n ){
     
    	int i, j, t=0;
     
    	for(i = 0; i < n; i++){
     
    		for(j = 1; j < (n-i); j++){
     
    		if(a[j-1] > a[j]){
     
    		t = a[j-1];
     
    		a[j-1]=a[j];
     
    		a[j]=t;
    		}
    	}
    	}
    	}
      }
    }

  7. #7
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    Default Re: Bubble Sort help

    Please copy and paste here the FULL text of the error messages.

    Please enclose your code in code tags to preserve the formatting. Left adjusted code is hard to follow.
    See: Java Forums BB Code List

  8. #8
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    Default Re: Bubble Sort help

    Ok I hope and think I solved the previous 8 errors but now I am getting 1 error. It is a class, interface, enum expected error. Here is my code that I have so far and I will follow it with what cmd is giving me when I try and compile it.

    import java.util.Scanner;
    public class Homework5{
    public static void main(String[] args){
    Scanner input= new Scanner(System.in);
     
      System.out.println("Enter number of students: ");
     
    	int numberofstudents=input.nextInt();
     
    	double[] myList= new Double [num];
     
    	System.out.println("Enter " + myList.length + " Values");
     
    	for(int i=0; i < myList.length; i++){
     
    	myList[i]=input.nextDouble();
     
    	System.out.println("Enter student's name: ");
     
    	String[] studentsname = new String [num];
     
    	studentsname [i] = input.next();
     
    	System.out.println("Enter student's score: ");
     
    	String[] studentsscore = new String [num];
     
    	studentsscore [i] = input.next();
     
    	double[] myList= new double [num];
     
    	System.out.println("Enter " + myList.length + " Values");
     
    	for(int i=0; i < myList.length; i++){
     
    	myList[i]=input.nextDouble();
     
    	}
     
    	int i;
     
    	int array[]= {i};
     
    	System.out.println("Values before the sort");
     
      for(i = 0; i < array.length; i++)
     
    	System.out.print( array[i]+" ");
     
    	System.out.println();
     
    	bubble_sort(array, array.length);
     
    	System.out.println("Values after the sort");
     
    	for(i = 0; i < array.length; i++)
     
    	System.out.print(array[i]+" ");
     
    	System.out.println();
     
    	}
    	}
     
    		public static void bubble_sort( int a[], int n ){
     
    	int i, j, t=0;
     
    	for(i = 0; i < n; i++){
     
    		for(j = 1; j < (n-i); j++){
     
    		if(a[j-1] > a[j]){
     
    		t = a[j-1];
     
    		a[j-1]=a[j];
     
    		a[j]=t;
    		}
    	}
    	}
    	}
    	}
     }

    well it won't let me copy and paste the cmd screen. But it is saying Homework5.java :05:class, interface, enum expected }

  9. #9
    Super Moderator Norm's Avatar
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    Default Re: Bubble Sort help

    Please enclose your code in code tags to preserve the formatting. Left adjusted code is hard to follow.

    copy and paste the cmd screen
    To copy the contents of the command prompt window:
    Click on Icon in upper left corner
    Select Edit
    Select 'Select All' - The selection will show
    Click in upper left again
    Select Edit and click 'Copy'

    Paste here.

  10. #10
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    Default Re: Bubble Sort help

    You code is unreadable. Check the Code Tag link in copeg's signature.

    I suspect your problem is that you have the bubblesort method inside the main method. Make sure your opening and closing braces { } match up correctly.

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