Parsing a string array in java

Question

sNums = scanString.nextLine();    
String[] num = sNums.split(" ");    
for (int i = 0; i < num.length; ++i)    
{    
    numbers = new double[i+1];     
    numbers[i] = Double.valueOf(num[i]);    
}    
for(double item: numbers)    
    out.print(item + " ");

I'm trying to change the String of numbers I have which is "num" in this case into an array of double. I'm pretty sure this should work but for some reason it's storing "0.0" into every element entered except for the last one. For example if I enter "1 5 7 90 52[enter]" the output should be "1.0 5.0 7.0...etc" but instead what I get is "0.0 0.0 0.0 0.0 52.0"

Solution 1

The problem you have is that you create a new array in loop. You should take it out and initialized.

  String[] num = sNums.split(" ");    
  double[] numbers = new double[num.length];   // The valid place for loop

  for (int i = 0; i < num.length; ++i)    
  {    
    numbers[i] = Double.valueOf(num[i]);    
  }    

  for(double item: numbers)  {
    out.print(item + " "); 
  }

Solution 2

You're recreating the array each time in the for loop. Also you're using a for each at the second for and not using it, using i instead. That would not compile since i was never declared in that scope.. Anyway I suggest you forget about arrays in Java and use Lists, they're much more convenient.

    sNums = scanString.nextLine();    
    final String[] num = sNums.split(" ");    
    final List<Double> numbers = new ArrayList<Double>();
    for (final String cur: num) {    
        numbers.add(Double.valueOf(cur));
    }    
    for(final Double item: numbers) {    
        out.print(item + " "); 
    }

Comments

[m0skit0]

This won't work. ArrrayIndexOutOfBoundsException at out.print(numbers[i] + " ");

[Damian Leszczyński - Vash]

@sᴜʀᴇsʜᴀᴛᴛᴀ, It for sure not perfect. If you use array list you can replace the first loop with foreach. And there is not need to introduce List and Object type. From my point of view this is over engineered.

[Damian Leszczyński - Vash]

That code will not throw ArrayIndexOutOfBoundsException It will not compile as the i was not defined. And the OP has changed the question so you answer is not valid to the question.

[m0skit0]

@Vash You're correct, it will not compile. About the question being changed, sorry I don't have time to keep track of that. It's OP problem.

[m0skit0]

@Vash Using List you don't need to allocate the array size explicitly. And I didn't introduce Object anywhere, OP is already using Double.valueOf().

[Damian Leszczyński - Vash]

The Double.valueOf() is a static method in class that return primitive double, no object there. What I tried to say is that as you do not allocate the array. You do not need that for with index i. for(String num : sNUms.split(" ") { numbers.add(Double.valueOf(num)); }, is enough.

[m0skit0]

Sorry, Double.valueOf returns Double, not double. Yeah, you don't need the i index, same as second for.

[Damian Leszczyński - Vash]

You have right with that. The parseDouble return double. ;-).