There are two in-built methods to sort in Java.
- Arrays.Sort() works for arrays which can be of primitive data type also.
// A sample Java program to demonstrate working of
// Arrays.sort().
// It by default sorts in ascending order.
import
java.util.Arrays;
public
class
GFG {
public
static
void
main(String[] args)
{
int
[] arr = {
13
,
7
,
6
,
45
,
21
,
9
,
101
,
102
};
Arrays.sort(arr);
System.out.printf(
"Modified arr[] : %s"
,
Arrays.toString(arr));
}
}
Output:
Modified arr[] : [6, 7, 9, 13, 21, 45, 101, 102]
- Collections.sort() works for objects Collections like ArrayList and LinkedList.
// Java program to demonstrate working of Collections.sort()
import
java.util.*;
public
class
GFG {
public
static
void
main(String[] args)
{
// Create a list of strings
ArrayList<String> al =
new
ArrayList<String>();
al.add(
"Geeks For Geeks"
);
al.add(
"Friends"
);
al.add(
"Dear"
);
al.add(
"Is"
);
al.add(
"Superb"
);
/* Collections.sort method is sorting the
elements of ArrayList in ascending order. */
Collections.sort(al);
// Let us print the sorted list
System.out.println(
"List after the use of"
+
" Collection.sort() : "
+ al);
}
}
Output:
List after the use of Collection.sort() : [Dear, Friends, Geeks For Geeks, Is, Superb]
- Which sorting algorithm does Java use in sort()?
Java’s Arrays.sort method uses Quicksort for arrays of primitives and merge sort for arrays of objects. - Which order of sorting is done by default?
It by default sorts in ascending order. - How to sort array or list in descending order?
It can be done with the help of Collections.reverseOrder().Example:
- For Arrays.sort()
// A sample Java program to sort an array
// in descending order using Arrays.sort().
import
java.util.Arrays;
import
java.util.Collections;
public
class
GFG {
public
static
void
main(String[] args)
{
// Note that we have Integer here instead of
// int[] as Collections.reverseOrder doesn't
// work for primitive types.
Integer[] arr = {
13
,
7
,
6
,
45
,
21
,
9
,
2
,
100
};
// Sorts arr[] in descending order
Arrays.sort(arr, Collections.reverseOrder());
System.out.printf(
"Modified arr[] : %s"
,
Arrays.toString(arr));
}
}
Output:
Modified arr[] : [100, 45, 21, 13, 9, 7, 6, 2]
- For Collections.sort()
// Java program to demonstrate working of Collections.sort()
// to descending order.
import
java.util.*;
public
class
GFG {
public
static
void
main(String[] args)
{
// Create a list of strings
ArrayList<String> al =
new
ArrayList<String>();
al.add(
"Geeks For Geeks"
);
al.add(
"Friends"
);
al.add(
"Dear"
);
al.add(
"Is"
);
al.add(
"Superb"
);
/* Collections.sort method is sorting the
elements of ArrayList in ascending order. */
Collections.sort(al, Collections.reverseOrder());
// Let us print the sorted list
System.out.println(
"List after the use of"
+
" Collection.sort() : "
+ al);
}
}
Output:
List after the use of Collection.sort() : [Superb, Is, Geeks For Geeks, Friends, Dear]
- For Arrays.sort()
- How to sort only a subarray?
Example:// A sample Java program to sort a subarray
// using Arrays.sort().
import
java.util.Arrays;
public
class
GFG {
public
static
void
main(String[] args)
{
// Our arr contains 8 elements
int
[] arr = {
13
,
7
,
6
,
45
,
21
,
9
,
2
,
100
};
// Sort subarray from index 1 to 4, i.e.,
// only sort subarray {7, 6, 45, 21} and
// keep other elements as it is.
Arrays.sort(arr,
1
,
5
);
System.out.printf(
"Modified arr[] : %s"
,
Arrays.toString(arr));
}
}
Output:
Modified arr[] : [13, 6, 7, 21, 45, 9, 2, 100]
- How to write my own sorting function in Java?
Please see Java programs for Quick Sort, Merge Sort, Insertion Sort, Selection Sort, Heap Sort, Bubble Sort
How to sort objects of user defined data type?
Please refer Arrays.sort() in Java and Collections.sort() in Java for examples.
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