Sorting values off array in Java

Question

I am new to this site and new to java so pleas help me out. If i have array of positive and negative numbers all are int, how to sort all the positive ones in a new array and all negative in a other new array.

Answer 1

Asking a question in StackOverflow without any selfstudy on basics would attract downvotes. Kindly take time in doing your research. However to make you understand the way to solve I am providing you with a solution.

Step 1: You have an array of positive and negative values

Integer[] initialArray = new Integer[10];

//This contains the list of all values.

Step 2: Create two ArrayLists to save the negative and positive values in each of these.

ArrayList<Integer> positiveValues = new ArrayList<>();
ArrayList<Integer> negativeValues = new ArrayList<>();

Step 3: Iterate through initialArray and save the respective values in both lists.

for(int i =0; i< initialArray.length; i++) {
  if(initialArray[i] < 0) {
    negativeValues.add(initialArray[i]);
  } else {
    positiveValues.add(initialArray[i]);
  }
}

Step 4: Now sort the values

Collections.sort(negativeValues);
Collections.sort(positiveValues);

Step 5: If Required If you need in arrays instead of ArrayList,

Integer[] negativeArray = new Integer[negativeValues.size()];
Integer[] positiveArray = new Integer[positiveValues.size()];

And cast these to get the array

Answer 2

I actually think this is a pretty good question. Here is an implementation you can try using Java 8 streams.

Given an integer array full of mixed negative/positive numbers:

int[] a = new int[] { 5, 6, 7, 4, -2, 5, -9, 2 };

One solution could be as follows:

int[] pos = Arrays.stream(a).filter(i -> i >= 0).sorted().toArray();
int[] neg = Arrays.stream(a).filter(i -> i < 0).sorted().toArray();

The pos[] array will have all the positive numbers sorted, and neg[] all the negative numbers sorted. The only thing I really dislike is that a[] is traversed twice, but at least it is short.

Answer 3

First seperate positive and negative numbers. I mean find size of positive numbers and create-set new positive numbers array. Then find size of negative numbers and create-set new negative numbers array.

Then just call sort method on both arrays.

Arrays.sort(array);