JAVA EXAMPLE PROGRAMS

JAVA EXAMPLE PROGRAMS

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Program: Write an example for Collections.checkedSet() method.


Description:

Collections.checkedSet() method returns a dynamically typesafe view of the specified set. Any attempt to insert an element of the wrong type will result in an immediate ClassCastException. Assuming a set contains no incorrectly typed elements prior to the time a dynamically typesafe view is generated, and that all subsequent access to the set takes place through the view, it is guaranteed that the set cannot contain an incorrectly typed element.


Code:
package com.java2novice.collections;

import java.util.Collections;
import java.util.HashSet;
import java.util.Set;

public class MyCheckedSet {

	public static void main(String a[]){
		
		Set mySet = new HashSet();
		mySet.add("one");
		mySet.add("two");
		mySet.add("three");
		mySet.add("four");
		Set chkSet = Collections.checkedSet(mySet, String.class);
		System.out.println("Checked set content: "+chkSet);
		//you can add any type of elements to mySet object
		mySet.add(10);
		//you cannot add any type of elements to chkSet object, doing so
		//throws ClassCastException
		chkSet.add(10); //throws ClassCastException
	}
}

Output:
Checked set content: [two, one, three, four]
Exception in thread "main" java.lang.ClassCastException: Attempt to insert class java.lang.Integer element into
							collection with element type class java.lang.String
	at java.util.Collections$CheckedCollection.typeCheck(Collections.java:2202)
	at java.util.Collections$CheckedCollection.add(Collections.java:2243)
	at com.java2novice.collections.MyCheckedSet.main(MyCheckedSet.java:22)
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List Of All Collections Class Sample Programs:

  1. How to add all elements to the given collection object?
  2. Write an example for Collections.asLifoQueue() method.
  3. How to search user defined object from a List by using binary search?
  4. Write an example for Collections.checkedCollection() method.
  5. Write an example for Collections.checkedList() method.
  6. Write an example for Collections.checkedSet() method.
  7. Write an example for Collections.checkedMap() method.
  8. How to check there in no common element between two list objects by using Collections.disjoint() method?
  9. How to create empty list using Collections class?
  10. How to create empty set using Collections class?
  11. How to create empty map using Collections class?
  12. How to Enumeration for ArrayList object?
  13. How to fill or replace elements of a List or ArrayList?
  14. How to find repeated element cound (frequency) of a given collection?
  15. How to convert Enumeration to List object?
  16. How to get index of a sub list from another list?
  17. How to get last index of a sub list from another list?
  18. How to get max element from the given list?
  19. How to get min element from the given list?
  20. How to get max element of a list of user defined objects?
  21. How to get min element of a list of user defined objects?
  22. How to get max element of a list of user defined objects using Comparator?
  23. How to get min element of a list of user defined objects using Comparator?
  24. How to create multiple copies of a given object?
  25. How to replace all occurances of a given object in the list?
  26. How to rotate elements in the list by specified distance?
  27. How to create synchronized list?
  28. How to create synchronized set?
  29. How to create synchronized map?
Knowledge Centre
What is abstract class or abstract method?
We cannot create instance for an abstract class. We can able to create instance for its subclass only. By specifying abstract keyword just before class, we can make a class as abstract class.

public abstract class MyAbstractClass{

}

Abstract class may or may not contains abstract methods. Abstract method is just method signature, it does not containes any implementation. Its subclass must provide implementation for abstract methods. Abstract methods are looks like as given below:

public abstract int getLength();
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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.
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