Arrays.sort() in Java

In Java, sort() method is a static and overloaded method defined in the java.util.Arrays class. It is used to sort arrays values of different types. It is widely used to organize data in ascending order. The sort() method can be applied with primitive types (int, char, double, float, etc.) and object type (String, Integer, Double, etc.). Note that the method uses a dual-pivot Quicksort algorithm for primitive types and a modified merge sort for object arrays that ensures efficient sorting.

Each sort() method provides the following two variants:

1. Sorting the entire array (it may be an integer or character array)
2. Sorting a specific range by passing the starting and ending indices.

Examples of Arrays.sort() Method

Sorting an Array of Primitive Data Types

Output:

Sorted Integer Array: 1, 2, 3, 5, 8, 11, 12, 14, 17
Sorted Float Array: 1.05, 1.2, 2.2, 3.89, 5.4, 5.6, 6.7
Sorted Double Array: 1.5, 2.7, 3.2, 4.8, 5.1, 6.8
Sorted Character Array: a, b, b, c, d, k, l, y

Example: Sorting a Subarray

Output:

Sorted Integer Array: 12, 8, 5, 1, 3, 11, 14, 17, 2
Sorted Float Array: 1.2, 6.7, 1.05, 2.2, 5.4, 5.6, 3.89
Sorted Double Array: 1.5, 6.8, 2.7, 3.2, 4.8, 5.1
Sorted Character Array: b, a, b, c, d, l, y, k

Similarly, we can sort short and byte type array.

Example: Sorting a String

Output:

[Australia, Austria, London, Paris, South Africa]

Example: Custom Sorting with Comparator

Output:

912 Tom New York
917 Peter Amsterdam
1024 Jack Las Vegas

Example: Sorting Comparable Interface

Output:

912 Tom New York
917 Peter Amsterdam
1024 Jack Las Vegas

Important Points to Remember

1. Object elements should implement Comparable if no Comparator is provided.
2. Use Comparator.nullsFirst() or Comparator.nullsLast() to handle nulls safely.
3. Partial sort is great when we only need to sort a segment of the array.
4. For large arrays (for example, 10,000 elements), consider Arrays.parallelSort().
5. String sorting uses Unicode values. For locale-sensitive sorting, use Collator.

Conclusion

The Java Arrays.sort() method is an enormously powerful and versatile tool that not only sorts primitive arrays but does it for object arrays as well. Its simple syntax and overloaded methods make it possible for developers to perform anything from this one-dimensional basic numeric sorting to an advanced custom logic with comparators. It well sustains a wide universe of use case scenarios through optimized ones such as dual-pivot Quicksort for primitives.

Whether you are creating small utilities or more complex applications, you will find Arrays.sort() a very beneficial routine for managing data, writing cleaner code, and developing software with a better design.

Java Arrays.sort() MCQs

1. Which method we should use to sort a subarray of integer type?

1. sort(int[] a)
2. sort(int[] a, int fromIndex)
3. sort(int[] a, int fromIndex, int toIndex)
4. sort(Integer[] a)

2. Which algorithm is used by the sort() method to sort primitive type?

1. Dual-Pivot Quicksort
2. Pivot Quicksort
3. Quicksort
4. Pivot Sort

3. Which algorithm is used by the sort() method to sort object types?

1. Dual-Pivot Merge Sort
2. Quicksort
3. Merge Sort
4. Modified Merge Sort

4. In which class the sort() method is defined?

1. io.Arrays Class
2. util.Arrays Class
3. lang.Arrays Class
4. util.Array Class

5. The sort() method is a _______ method of the Arrays class?

1. Overloaded Method
2. Abstract Method
3. Static Method
4. 1 and 3 only