- The set interface extends the collection interface in java.
- Does not allow duplication
- Allows only unique things.
- Does not provide positional access.
Set<String> set = Set.of("Apple", "Banana", "Cat");
System.out.println(" Set : " + set);- Hash Set does not allow duplication.
- Does not care about the insertion order.
- Does not care about sorded order
- It uses hash table.
package setInterface;
import java.util.HashSet;
import java.util.Set;
public class HashsetClass {
public static void main(String[] args) {
Set<Integer> numbers = new HashSet<>();
// adding elements in hashset
numbers.add(29);
numbers.add(23);
numbers.add(3);
numbers.add(2);
System.out.println(" Hashset is : " + numbers);
}
}
- Care about insertion order.
- No duplication allowed.
- Does not care about sorted order.
package setInterface;
import java.util.LinkedHashSet;
import java.util.Set;
public class LinkedHashSetClass {
public static void main(String[] args) {
Set<Integer> numbers = new LinkedHashSet<>();
// adding elements in hashset
numbers.add(29);
numbers.add(23);
numbers.add(3);
numbers.add(2);
System.out.println("Linked Hashset is : " + numbers);
}
}
- Stores data in sorted order.
- The left side data is smaller than the node and the right side data is larger than the node.
- Insertion, deletion and searching are not costly.
- Does not allow duplication.
- It implements Navigable set so it provides more function then hash set or linked set.
package setInterface;
import java.util.Set;
import java.util.TreeSet;
public class TreeSetClass {
public static void main(String[] args) {
// TODO Auto-generated method stub
TreeSet<Integer> numbers = new TreeSet<>();
// adding elements in tree set
numbers.add(29);
numbers.add(23);
numbers.add(3);
numbers.add(2);
numbers.add(92);
System.out.println("Tree Set is : " + numbers);
}
}
`To take an example we have created the tree set which has the following below elements.
Tree Set is : [1, 2, 3, 12, 23, 29, 40, 45, 92, 99]
- floor() : to find lower than any number say 40, it displays only 1 number and inclusive of the number.
for above set it shows 40 - lower (): we use lower () to get exclusive that number say 40.
for above set it show 29. - ceiling() : to find higher than any number say 40, it displays only 1 number and is inclusive of the number.
for above set it shows 40 - higher(): we use lower () to get exclusive that number say 40.
for the above, set it show 45. - subset() : to get subset between two numbers (3,40).
In this lower limit is inclusive and upper limit is exclusive
O/P – [3, 12, 23, 29] - tailSet(40) : get all number smaller then a number inclusive
O/P – [40, 45, 92, 99] - headSet(40) : get all number greater then a number exclusive
O/P – [1, 2, 3, 12, 23, 29]
package setInterface;
import java.util.Set;
import java.util.TreeSet;
public class TreeSetClass {
public static void main(String[] args) {
// TODO Auto-generated method stub
TreeSet<Integer> numbers = new TreeSet<>(Set.of(1, 3, 99, 12, 45, 40));
// adding elements in tree set
numbers.add(29);
numbers.add(23);
numbers.add(3);
numbers.add(2);
numbers.add(92);
System.out.println("Tree Set is : " + numbers);
// to find lower than any number say 40, it display only 1 number
// and inclusive of the number
System.out.println("number lower than 40 : " + numbers.floor(40));
// O/P - 40
// we use lower() to get exclusive of that number
System.out.println("number lower than 40 : " + numbers.lower(40));
// O/P - 29
// to find greater than any number say 40, it display only 1 number
// and inclusive of the number
System.out.println("number lower than 40 : " + numbers.ceiling(40));
// O/P - 40
// we use lower() to get exclusive of that number
System.out.println("number lower than 40 : " + numbers.higher(40));
// O/P - 45
// to get subset between two numbers (3,40)
System.out.println("get subset between two numbers : " + numbers.subSet(3, 40));
// O/P - [3, 12, 23, 29]
// get all number greater then a number exclusive
System.out.println("headSet(40) : " + numbers.headSet(40));
// O/P - [1, 2, 3, 12, 23, 29]
// get all number smaller then a number inclusive
System.out.println("tailSet(40) : " + numbers.tailSet(40));
// O/P - [40, 45, 92, 99]
}
}
