Java Articles - Page 162 of 540

A lambda expression passed in a method that has an argument of type of functional interface. If we need to pass a lambda expression as an argument, the type of parameter receiving the lambda expression argument must be of a functional interface type.In the below example, the lambda expression can be passed in a method which argument's type is "TestInterface". Exampleinterface TestInterface {    boolean test(int a); } class Test {    // lambda expression can be passed as first argument in the check() method    static boolean check(TestInterface ti, int b) {       return ti.test(b);    } } public class ... Read More

The lambda expressions consist of two parts, one is parameter and another is an expression and these two parts have separated by an arrow (->) symbol. A lambda expression can access a variable of it's enclosing scope. A Lambda expression has access to both instance and static variables of it's enclosing class and also it can access local variables which are effectively final or final.Syntax( argument-list ) -> expressionExampleinterface TestInterface {    void print(); } public class LambdaExpressionTest {    int a; // instance variable    static int b; // static variable    LambdaExpressionTest(int x) {    // constructor to initialise instance variable       this.a = ... Read More

This Question comes to many professionals who are not actually into core technical and want to pursue their career in Selenium Automation. The term coding makes the non-programmers a bit scare to even start off with something like automation. There is a perception that a non-programmer cannot excel in Automation, but it is only in head. Many deserving and capable manual testers shy away from Selenium just thinking that it require some special skills.There are various many languages in which Selenium Scripts are designed such as Python, Ruby, C#, JavaScript and Java is one such of them. Knowing the popularity ... Read More

Java supports lambda expressions but not the Closures. A lambda expression is an anonymous function and can be defined as a parameter. The Closures are like code fragments or code blocks that can be used without being a method or a class. It means that Closures can access variables not defined in its parameter list and also assign it to a variable.Syntax([comma seperated parameter-list]) -> {body}In the below example, the create() method has a local variable "value" with a short life and disappears when we exit the create() method. This method returns the closure to the caller in the main() method after that ... Read More

In this article, we will learn how to count the number of columns in a MySQL table using JDBC. We will be using the ResultSetMetaData to get details of the table by using simple examples. What is ResultSetMetaData? The ResultSetMetaData is an interface that is present in the java.sql package. Using ResultSetMetaData, we can get information about the table, for example, what are the column names of each and every table, and how many columns are there?. To create the object for ResultSet: ResultSet rs=st.executeQuery("Select * from Student"); The executeQuery method writes the records, which are then stored in the ... Read More

The effectively final variables refer to local variables that are not declared final explicitly and can't be changed once initialized. A lambda expression can use a local variable in outer scopes only if they are effectively final.Syntax(optional) (Arguments) -> bodyIn the below example, the "size" variable is not declared as final but it's effective final because we are not modifying the value of the "size" variable.Exampleinterface Employee {    void empData(String empName); } public class LambdaEffectivelyFinalTest {    public static void main(String[] args) {       int size = 100;       Employee emp = name -> {        // lambda ... Read More

A lambda expression is an anonymous function without having any name and does not belong to any class that means it is a block of code that can be passed around to execute.Syntax(parameter-list) -> {body}We can implement a lambda expression without creating an anonymous inner class in the below program. For the button's ActionListener interface, we need to override one abstract method addActionListener() and implement the block of code using the lambda expression.Exampleimport java.awt.*; import java.awt.event.*; import javax.swing.*; public class LambdaExpressionButtonTest extends JFrame {    private JButton btn;    public LambdaExpressionButtonTest() {       btn = new JButton("Click on the button"); ... Read More

Anonymous class is an inner class without a name, which means that we can declare and instantiate class at the same time. A lambda expression is a short form for writing an anonymous class. By using a lambda expression, we can declare methods without any name.Anonymous class vs Lambda ExpressionAn anonymous class object generates a separate class file after compilation that increases the size of a jar file while a lambda expression is converted into a private method. It uses invokedynamic bytecode instruction to bind this method dynamically, which saves time and memory.We use this keyword to represent the current class in lambda expression while in the ... Read More

The lambda expressions are introduced in Java 8. It is one of the most popular features of Java 8 and brings functional programming capabilities to Java. By using a lambda expression, we can directly write the implementation for a method in Java.In the below program, we can create a thread by implementing the Runnable interface using lamda expression. While using the lambda expressions, we can skip the new Runnable() and run() method because the compiler knows that Thread object takes a Runnable object and that contains only one method run() that takes no argument.Examplepublic class LambdaThreadTest {    public static void main(String args[]) {     ... Read More

Yes, any lambda expression is an object in Java. It is an instance of a functional interface. We have assigned a lambda expression to any variable and pass it like any other object.Syntax(parameters) -> expression              or (parameters) -> { statements; }In the below example, how a lambda expression has assigned to a variable and how it can be invoked.Example@FunctionalInterface interface ComparatorTask {    public boolean compare(int t1, int t2); } public class LambdaObjectTest {    public static void main(String[] args) {       ComparatorTask ctask = (int t1, int t2) -> {return t1 ... Read More