[Myntal]

How would one use an enhanced for loop to make an array from imported data in a .txt file?
Please and thank you.
(Examples would be nice)

[syfran]

That is a very specific question and would require a lot more than a for each loop. Look into file reading to start.

[rules][/rules]

This post has been edited by syfran: 13 October 2009 - 10:33 AM

[Myntal]

So I need to be able to read doubles from a .txt file and put it into an array using a for-each loop. I thought this would be the start, but there is a possible loss of precision. Any help would be nice.

import java.util.Scanner;
import java.io.File;
import java.io.IOException;
public class HeatIndex
{
   public static void main(String[] args) throws IOException
   {
	   
	  Scanner in = new Scanner(System.in);	  
		 
	  Scanner LAtemp = new Scanner (new File("LATempTest.txt"));
	  double LAtempA[] = new double[13];  
	  
	  for (double i : LAtempA) 
	  {
		  LAtempA[i] = LAtemp.nextDouble(); 
		  i++;
		  
	  }
	  
   }
}

[syfran]

Why do you need a for-each loop here? why not the plain old for loop?

[pbl]

	for (double i : LAtempA) 
	  {
		  i = LAtemp.nextDouble(); 
	  }

i++ is just incrementing your Double by 1
and i is the Double not an index to it within the array

[Myntal]

How am I supposed to assign that counter as the index?

import java.util.Scanner;
import java.io.File;
import java.io.IOException;
import java.util.InputMismatchException; 
public class HeatIndex
{
   public static void main(String[] args) throws IOException
   {
	   
	  Scanner in = new Scanner(System.in);	  
		 
	  Scanner LAtemp = new Scanner (new File("LATempTest.txt"));
	  
	  double LAtempA[] = new double[11];  
	  
	  for (double i : LAtempA) 
	  {
		  i = LAtemp.nextDouble(); 
		  
		  System.out.println(LAtempA[1]);		  
	  }
	  
   }
}

This post has been edited by Myntal: 14 October 2009 - 10:24 AM

[macosxnerd101]

 for (double i : LAtempA) 
	  {
		  i = LAtemp.nextDouble(); 
	  }

Think of the variable i in this loop as an intermediary. In case you didn't know, the enhanced for loop (or foreach loop for short) automates a for loop iterating through a collection. The variable declared to the left of the colon, in this case i, obtains the value of the next element, starting at the beginning, from each iteration. So by manipulating/assigning or refferencing i, you are inherently manipulating or refferencing each element in the array (one element per iteration).

[Myntal]

So, would you reccomend using a normal for loop. I am still pretty unclear about the foreach loops. I have been researching and I can't find a basic explanation.

[AntonWebsters]

A normal for loop can do what a foreach loop can do...so if you're not used to using foreach loop, then just use a normal for loop...

[macosxnerd101]

AntonWebsters, on 15 Oct, 2009 - 11:40 AM, said:

A normal for loop can do what a foreach loop can do...so if you're not used to using foreach loop, then just use a normal for loop...

Kind of. A foreach loop basically iterates right through a collection, not pausing for anything, and you can't see the indices. With a regular for loop, you have access to the indices in the array and you have more flexibility in how you iterate (ie., you can increment by 2, 3, 4, etc.; in a foreach loop, you go to the next element on each iteration).

[LaFayette]

foreach is a special case of a for loop, implemented as sugar. Hence a normal loop can do what a foreach can.