Java Collections checkedSet() Method

---

---

Description

The Java Collections checkedSet(Set<E>, Class<E>) method is used to get a dynamically typesafe view of the specified set.

Declaration

Following is the declaration for java.util.Collections.checkedSet() method.

public static <E> Set<E> checkedSet(Set<E> s, Class<E> type)

Parameters

• s − This is the set for which a dynamically typesafe view is to be returned.

• type −- This is the type of element that s is permitted to hold.

Return Value

The method call returns a dynamically typesafe view of the specified set.

Exception

NA

Getting a TypeSafe Set from a Set of Integer Example

The following example shows the usage of Java Collection checkedSet(Set,Class ) method to get a typesafe view of set of integers. We've created a set object with some integers, printed the original set. Using checkedSet(Set, Integer) method, we're getting a set of Integer and then it is printed.

package com.tutorialspoint;

import java.util.Collections;
import java.util.Set;
import java.util.TreeSet;

public class CollectionsDemo {

   public static void main(String[] args) {
      Set<Integer> set = new TreeSet<>();

      set.add(1);
      set.add(2);
      set.add(3);
      set.add(4);
      set.add(5);

      System.out.println("Initial collection value: " + set);

      Set<Integer> safeSet = Collections.checkedSet(set, Integer.class);
      System.out.println("Typesafe View: "+safeSet);
   }
}

Output

Let us compile and run the above program, this will produce the following result.

Initial collection value: [1, 2, 3, 4, 5]
Typesafe View: [1, 2, 3, 4, 5]

Getting a TypeSafe Set from a Set of String Example

The following example shows the usage of Java Collection checkedSet(Set,Class ) method to get a typesafe view of set of strings. We've created a set object with some integers, printed the original set. Using checkedSet(Set, String) method, we're getting a set of String and then it is printed.

package com.tutorialspoint;

import java.util.Collections;
import java.util.Set;
import java.util.TreeSet;

public class CollectionsDemo {

   public static void main(String[] args) {
      Set<String> set = new TreeSet<>();

      set.add("Welcome");
      set.add("to");
      set.add("Tutorialspoint");

      System.out.println("Initial collection value: " + set);

      Set<String> safeSet = Collections.checkedSet(set, String.class);
      System.out.println("Typesafe View: "+safeSet);
   }
}

Output

Let us compile and run the above program, this will produce the following result.

Initial collection value: [Tutorialspoint, Welcome, to]
Typesafe View: [Tutorialspoint, Welcome, to]

Getting a TypeSafe Set from a Set of Objects Example

The following example shows the usage of Java Collection checkedSet(Set,Class ) method to get a typesafe view of set of Student objects. We've created a Set object with some student objects, printed the original set. Using checkedSet(Set, Student) method, we're getting a Set of Students and then it is printed.

package com.tutorialspoint;

import java.util.Collections;
import java.util.Set;
import java.util.TreeSet;

public class CollectionsDemo {

   public static void main(String[] args) {
      Set<Student> set = new TreeSet<>();

      set.add(new Student(1, "Julie"));
      set.add(new Student(2, "Robert"));
      set.add(new Student(3, "Adam"));

      System.out.println("Initial collection value: " + set);

      Set<Student> safeSet = Collections.checkedSet(set, Student.class);
      System.out.println("Typesafe View: "+safeSet);
   }
}
class Student implements Comparable<Student> {
   int rollNo;
   String name;

   Student(int rollNo, String name){
      this.rollNo = rollNo;
      this.name = name;
   }

   @Override
   public String toString() {
      return "[ " + this.rollNo + ", " + this.name + " ]";
   }

   @Override
   public int compareTo(Student student) {
      return student.rollNo - this.rollNo;
   }
}

Output

Let us compile and run the above program, this will produce the following result.

Initial collection value: [[ 3, Adam ], [ 2, Robert ], [ 1, Julie ]]
Typesafe View: [[ 3, Adam ], [ 2, Robert ], [ 1, Julie ]]