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Page 308 of 589
Checking for Null or Empty in Java.
A string is a collection of characters. In Java, it is represented by the String class, and it accepts NULL values. Checking for Null or Empty in Java In this article, we will learn if a string is null or empty in Java. The following are the ways to check if a string is null or empty in Java: Using isEmpty() Method Using length() Method Using isBlank() Method Using isEmpty() Method The isEmpty() method of the String class checks if a string is empty. It returns TRUE if ...
Read MoreCan we call a method on \"this\" keyword from a constructor in java?
The “this" keyword in Java is used as a reference to the current object within an instance method or a constructor. Using this, you can refer to the members of a class, such as constructors, variables, and methods. Calling a Method using "this" From a Constructor Yes, as mentioned, we can call all the members of a class (methods, variables, and constructors) from instance methods or constructors. Example In the following Java program, the Student class contains two private variables, name and age, with setter methods and a parameterized constructor that accepts these two values. From the constructor, we are ...
Read MoreGet Size of Java LinkedHashSet
LinkedHashSet is a collection in Java that maintains the insertion order of elements. It is part of the Java Collections Framework and extends the HashSet class. It stores unique elements and allows null values, but only one null element. It is similar to HashSet; the main difference is that a LinkedHashSet maintains a linked list holding of the entries of the current object, allowing it to maintain the order of elements. Let's learn how to get the size of a LinkedHashSet in Java. The following are some example scenarios: Scenario 1 Input : set = {1, 2, 3, 4, ...
Read MoreGet an element from a Stack in Java without removing it
The Stack is a data structure that is used to store elements in a Last In First Out (LIFO) manner. In Java, a stack is represented by the java.util.Stack class. It provides methods to create and manipulate a stack. Get an Element of a Stack without Removing it The pop() method of the Stack class removes the element at the top of the stack and returns it. But there is no direct way to access an element without removing it. However, we can see/view the top element of a Stack in Java using the peek() method. This method returns the ...
Read MoreCan a constructor be made final in Java?
A constructor is a special method in Java that is used to initialize objects. It gets called when an instance of a class is created. The constructor has the same name as the class and does not have a return type. The question is whether a constructor can be declared or made final in Java? The answer is no. Let's understand why. Why can't we declare a Java Constructor "final"? In Java, the final keyword is used to restrict modification of the members of a class (methods and variables). For example, a final method of a class cannot be overridden ...
Read MoreHow to iterate over a TreeMap in Java?
TreeMap is based on the Red-Black tree structure, which is a It is a part of the Java Collections Framework. It is a sorted map and maintains the order of its keys. Its order depends on the natural ordering of the keys or by a Comparator.Since the TreeMap is not a Collection, we cannot use the for-each loop to iterate through it. Instead, we can use the entrySet() method to get a set view of the mappings contained in the map, which we can then iterate over to access the keys and values. Let's explore some scenarios to understand the ...
Read MoreIterate through elements of Java LinkedHashSet
LinkedHashSet is a part of Java's Collection Framework. It is a type of Set that keeps the order of elements the same as they were added. It uses a combination of a hash table and a linked list to store elements.Our task is to traverse/iterate through the elements of a LinkedHashSet in Java. Let's look at some scenarios to understand the problem better: Scenario 1 Input: {1, 2, 3, 4, 5} Output: 1 2 3 4 5 Explanation: The LinkedHashSet contains the elements 1, 2, 3, 4, and 5. When we iterate through it, we get the elements in the ...
Read MoreCheck if a Java HashSet Collection contains another Collection
HashSet is a class in Java that implements the Set interface. It is used for storing unique elements. Our task is to check if a HashSet contains another collection in Java. Let's look at some scenarios to understand the problem better: Scenario 1 Input: {1, 2, 3, 4, 5} Collection to check: {2, 3} Output: true Explanation: The HashSet contains all the elements of the collection {2, 3}. Scenario 2 Input: {1, 2, 3, 4, 5} Collection to check: {6, 7} Output: false Explanation: The HashSet does not contain all the elements of the collection {6, 7}. Checking ...
Read MoreCheck if a particular key exists in Java LinkedHashMap
LinkedHashMap is a data structure in Java that is part of the Java Collections Framework. It is very similar to HashMap.It stores key-value pairs, where each key is unique, and it allows null values, but allows only one null key. The main difference is that the LinkedHashMap returns the elements in the order they were inserted. This is because it maintains a linked list with entries in the map, which helps it to retain the insertion order of the elements. Our task is to check if a particular key exists in a LinkedHashMap in Java. Scenario 1 Following is a ...
Read MoreHow can we Implement a Stack using Queue in Java?
This article will discuss how to implement a Stack using a Queue in Java. Stack in Java In Java, a Stack is a subclass (child class) of the Vector class, and it represents a LIFO stack of objects, which stands for Last-in-First-Out. The last element added at the top of the stack (In) can be the first element to be removed (Out) from the stack. The following diagram will give you a clear idea about the Stack: Queue in Java In Java, the Queue class extends the Collection interface, and it supports the insert and remove operations using a FIFO, ...
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