This method was introduced from Java 9. This method is similar to the ifPresent() method which I introduced in this tutorial, but here is a difference since we have one more Runnable parameter, so that in-case if the Optional object is empty, the object of the… Read More
This method is used to check whether an Optional object is empty or not? If not, then do the operations with this object, otherwise do not do anything. The parameter of this method is an object of the Consumer interface. You can see more about… Read More
The Optional object in Java has three methods with name start with or(). In this tutorial, we will together learn about them and what is the difference between them. First, I might mention the orElse() method. This method is used to return a default value in… Read More
Supplier is a Functional Interface, so it only contains an abstract method as follows:
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package java.util.function; /** * Represents a supplier of results. * * <p>There is no requirement that a new or distinct result be returned each * time the supplier is invoked. * * <p>This is a <a href="package-summary.html">functional interface</a> * whose functional method is {@link #get()}. * * @param <T> the type of results supplied by this supplier * * @since 1.8 */ @FunctionalInterface public interface Supplier<T> { /** * Gets a result. * * @return a result */ T get(); } |
This interface simply returns the value in the context that is being used by the get() method. For example, we have the following list:
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List<String> s = Arrays.asList("Khanh", "Quan"); |
Now that I want to… Read More
Java 8 introduces a new package containing Functional Interfaces called java.util.function. In this package, we have many interfaces like Consumer, Supplier, Predicate, … In this tutorial, we will learn about Consumer Functional Interface. The content of this interface is as follows:
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package java.util.function; import java.util.Objects; /** * Represents an operation that accepts a single input argument and returns no * result. Unlike most other functional interfaces, {@code Consumer} is expected * to operate via side-effects. * * <p>This is a <a href="package-summary.html">functional interface</a> * whose functional method is {@link #accept(Object)}. * * @param <T> the type of the input to the operation * * @since 1.8 */ @FunctionalInterface public interface Consumer<T> { /** * Performs this operation on the given argument. * * @param t the input argument */ void accept(T t); /** * Returns a composed {@code Consumer} that performs, in sequence, this * operation followed by the {@code after} operation. If performing either * operation throws an exception, it is relayed to the caller of the * composed operation. If performing this operation throws an exception, * the {@code after} operation will not be performed. * * @param after the operation to perform after this operation * @return a composed {@code Consumer} that performs in sequence this * operation followed by the {@code after} operation * @throws NullPointerException if {@code after} is null */ default Consumer<T> andThen(Consumer<? super T> after) { Objects.requireNonNull(after); return (T t) -> { accept(t); after.accept(t); }; } } |
Because the Consumer… Read More
This method is supported since Java 9. This method is used to create a new Stream object from an Optional object in Java. If the Optional object contains a value, this method will return the Stream object containing that value, otherwise, it returns an empty… Read More
Server Push is a new performance enhancement feature for Web applications defined in HTTP/2 standards. It allows us to push images, CSS files, Javascript files, and other resources to the client before requests from the client are processed. So, as soon as the response from… Read More
In the previous tutorial, you learned about Serialization that allows us to store the state of a Java object. All of the properties of the Java object are stored somewhere so that other processes can retrieve it to reuse. But in reality, sometimes we need… Read More
JDBC stands for Java Database Connectivity, which is an API that allows us to build applications that can access and manipulate with many different types of databases. In this tutorial, I will talk to you about the basic knowledge of JDBC. First, I will create… Read More
To migrate any file in Java, in Java 6 or older Java versions, we can use the renameTo() method located in the File object to do this:
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package com.huongdanjava.javaexample; import java.io.File; public class MoveFile { public static void main(String[] args) { File source = new File("F://source.txt"); File dest = new File("E://dest.txt"); if (source.renameTo(dest)) { System.out.println("Move file " + source.getAbsolutePath() + " to " + dest.getAbsolutePath() + " success."); } } } |
Result:
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Move file F:\source.txt to E:\dest.txt success |
From Java 7 onwards, we have another way to move a file, which is to… Read More
