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Object Oriented Programming Articles
Page 315 of 589
What are the useful commands in JShell in Java 9?
In this article, we will learn about useful commands in JShell. Java 9 has introduced a new interactive tool called JShell. This tool can be used to execute, test user-friendly and easy way of Java classes, interfaces, enums, objects, statements and etc. Different Useful Commands in JShell Below are some of the important commands in JShell: /open /var /types /methods /list /help /open To execute a script after JShell has started, we will use ...
Read MoreHow to define expressions, variables, and methods in JShell in Java 9?
JShell is a Read-Evaluate-Print Loop (REPL) that evaluates declarations, statements, and expressions as we have entered and immediately shows the results. This tool is run from the command prompt. Below, we can define expressions, variables, and methods in JShell. Expression The combination of variables, operators, and methods is known as an Expression in Java. They perform some logic that evaluates to a single value. int a=5, b=10, c=0; c=a+b; Here, "a+b" is an expression that evaluates the value of c as 15. Expression in JShell We can type any valid Java expression in JShell. The expression ...
Read MoreWhat is the use of the Cleaner class in Java 9?
In this article, we will learn about the use of the Cleaner class in Java 9. Below, we will first tell the basic usage and then we will know how we can use the Cleaner method practically. Garbage Collector An Object that has been created during the program execution is automatically removed by the Garbage Collector (GC). When an object not referenced by any thread and when JVM determines that this object can't be accessed, then it can be eligible for garbage collection. The finalize() method The Object class has a finalize() method, which is automatically called by GC before it attempts to remove the ...
Read MoreHow to save, edit, and drop a snippet in JShell in Java 9?
Java Shell or JShell is an official REPL(Read-Evaluate-Print-Loop) introduced with Java 9. It provides an interactive shell for quickly prototyping, debugging and without the need for the main() method or the need to compile the code before executing it. JShell is easily started by typing "jshell" in the command prompt. What are Snippets? JShell allows the execution of Java statements, variables, methods, class definitions, imports, and expressions. These pieces of Java code are referred to as snippets. Every snippet is assigned an ID(unique) that we can use later to reference it. Example Below is an example to represent a snippet ...
Read MoreWhen to use the ofNullable() method of Stream in Java 9?
In this article, we will learn to use the ofNullable() method of Stream in Java 9. We will first go through the Stream class, after that we will learn about the ofNullable() method along with its syntax and real-world use cases. Stream Class Stream was introduced in Java 8, the Stream API is used to process collections of objects. It represents a sequence of elements that support various operations to perform computations in parallel. Creating an instance of a stream: Stream stream; A stream is not a type of data structure, it takes input from Collections, Arrays, etc. The ofNullable() ...
Read MoreHow to find the last occurrence of an element in a Java List?
In this article, we will learn how to find the last occurrence of an element in a Java List. It is a collection in which we can store and access elements in serial order. We can use the following ways to find the last occurrence of an element in a Java List: Using a For Loop LastIndexOf() Method Using Stream API Using a For Loop We would use a for loop to iterate through the list in reverse order and check if the desiredelement is equal ...
Read MoreHow to determine if all elements are the same in a Java List?
In this article, we will explore how to determine if all elements in a Java List are the same. The following are the ways to achieve this: Using a For Loop Using Stream API Using a For Loop We will iterate through the list and compare each element with the first element. If we find any element that is not equal to the first element, we will return false. If we reach the end of the list without finding any different element, we will return true. Example In the below ...
Read MoreHow do I remove multiple elements from a list in Java?
A List extends a collection that is used to store elements in a sequential manner. Let's learn how to remove multiple elements from a list in Java. The following are a few ways to do that: Using a for Loop Using removeAll() Method Using Stream API Using a For Loop To remove multiple elements from a list using a for loop. We will iterate through the list and check if each element is in the list of elements to be removed. If it is, we will remove ...
Read MoreHow do I set the size of a list in Java?
Java list size is dynamic. It increases automatically whenever you add an element to it, and this exceeds the initial capacity. You can define the initial capacity at the time of list creation so that it allocates memory after the initial capacity is exhausted. We can do this using the ArrayList Constructor and Collections.nCopies() method. In this article, we will explore both methods to set the size of a list in Java. Using ArrayList Constructor Using Collections.nCopies() Let's explore these methods in detail. Using ArrayList Constructor We can create an ...
Read MoreHow to load a file into the JShell session in Java 9?
In this article, we will learn to load a file into the JShell session in Java 9. We will learn about Jshell and different ways we can load a file in Jshell, which is the command line and the /open command. What is a JShell? JShell is a new command-line interactive REPL (Read-Evaluate-Print-Loop) tool introduced in Java 9 to evaluate declarations, statements, and expressions written in Java. This tool also allows us to execute Java code snippets and get immediate results. Loading a file into the JShell There are two ways to load a file into the JShell session in ...
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