How to get slice of a Primitive Array in Java

Given a Primitive Array, the task is to get a Slice of this array in Java, using start and ending index.

Examples:

Input: arr[] = {1, 2, 3, 4, 5}, startIndex = 2, endIndex = 4
Output: {3, 4, 5}

Input: arr[] = {1, 2, 3, 4, 5}, startIndex = 0, endIndex = 1
Output: {1, 2}

• Method 1: Naive Method.
  1. Get the Array and the startIndex and the endIndex.
  2. Create and empty primitive array of size endIndex-startIndex.
  3. Copy the elements from startIndex to endIndex from the original array to the slice array.
  4. Return or print the slice of the array.

  Below is the implementation of the above approach:

  // Java program to Get a Slice
  // of a Primitive Array
  
  import java.util.Arrays;
  
  class GFG {
      // Function to get slice of a primitive array in Java
      public static int[] getSliceOfArray(int[] arr,
                                       int start, int end)
      {
  
          // Get the slice of the Array
          int[] slice = new int[end - start];
  
          // Copy elements of arr to slice
          for (int i = 0; i < slice.length; i++) {
              slice[i] = arr[start + i];
          }
  
          // return the slice
          return slice;
      }
      public static void main(String[] args)
      {
  
          // Get the array, startIndex and endIndex
          int[] arr = { 1, 2, 3, 4, 5 };
          int start = 2, end = 4;
  
          // Get the slice of the array
          int[] slice = getSliceOfArray(arr, start, end + 1);
  
          // Print the slice of the array
          System.out.println(Arrays.toString(slice));
      }
  }
  Output:

  [3, 4, 5]
  

• Method 2: Using Arrays.copyOfRange() method.
  1. Get the Array and the startIndex and the endIndex.
  2. Get the slice using Arrays.copyOfRange() method.
  3. Return or print the slice of the array.

  Below is the implementation of the above approach:

  // Java program to Get a Slice
  // of a Primitive Array
  
  import java.util.Arrays;
  
  class GFG {
      // Function to get slice of a primitive array in Java
      public static int[] getSliceOfArray(int[] arr,
                              int startIndex, int endIndex)
      {
  
          // Get the slice of the Array
          int[] slice = Arrays
                            .copyOfRange(
  
                                // Source
                                arr,
  
                                // The Start index
                                startIndex,
  
                                // The end index
                                endIndex);
  
          // return the slice
          return slice;
      }
      public static void main(String[] args)
      {
  
          // Get the array, startIndex and endIndex
          int[] arr = { 1, 2, 3, 4, 5 };
          int start = 2, end = 4;
  
          // Get the slice of the array
          int[] slice = getSliceOfArray(arr, start, end + 1);
  
          // Print the slice of the array
          System.out.println(Arrays.toString(slice));
      }
  }
  Output:

  [3, 4, 5]
  

• Method 3: Using Java 8 Streams
  1. Get the Array and the startIndex and the endIndex.
  2. Convert the specified range of elements from the startIndex to endIndex to Primitive Stream using range() method.
  3. Map the specified elements from the original array using map() method.
  4. Convert the mapped array into array using toArray() method.
  5. Return or print the slice of the array.

  Below is the implementation of the above approach:

  // Java program to Get a Slice
  // of a Primitive Array
  
  import java.util.Arrays;
  import java.util.stream.IntStream;
  
  class GFG {
  
      // Function to get slice of a primitive array in Java
      public static int[] getSliceOfArray(int[] arr,
                                int startIndex, int endIndex)
      {
  
          // Get the slice of the Array
          int[] slice = IntStream
  
                            // Convert the specified elements
                            // of array into IntStream
                            .range(startIndex, endIndex)
  
                            // Lambda expression to get
                            // the elements of IntStream
                            .map(i -> arr[i])
  
                            // Convert the mapped elements
                            // into the slice array
                            .toArray();
  
          // return the slice
          return slice;
      }
      public static void main(String[] args)
      {
  
          // Get the array, startIndex and endIndex
          int[] arr = { 1, 2, 3, 4, 5 };
          int start = 2, end = 4;
  
          // Get the slice of the array
          int[] slice = getSliceOfArray(arr, start, end + 1);
  
          // Print the slice of the array
          System.out.println(Arrays.toString(slice));
      }
  }
  Output:

  [3, 4, 5]