Java Misc

synchronized void method() {} public class SynchronizedInstanceMethodExample implements Runnable { public static void main(String[] args) { SynchronizedInstanceMethodExample runnable = new SynchronizedInstanceMethodExample(); new Thread(runnable).start(); // creates one thread new Thread(runnable).start(); // creates second thread } // Inherited run method from the Runnable interface @Override public void run() { try { // Calling the non-synchronized method print()…

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In this tutorial, we will see how to use the Java HttpClient to upload a file to the server. And in the following tutorial, you will learn how to configure HttpClient to accept all SSL certificates. So let’s begin.  In the below code example, I we will use the Apache HttpClient and the MultipartEntityBuilder. First,…

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Sometimes we need to consume HTTPS endpoints that do not have valid certificates.  We can do that by configuring the Java HttpClient to accept all SSL certificates, even from an untrusted Certificate Authority. Here you will see how to communicate with HTTPS endpoint that may not have a valid SSL certificate. In the following example,…

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import org.apache.http.HttpResponse; import org.apache.http.HttpHeaders; import org.apache.http.client.methods.HttpUriRequest; import org.apache.http.client.methods.RequestBuilder; import org.apache.http.impl.client.BasicResponseHandler; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import java.io.IOException; public class Test { public static void main(String[] args) throws IOException { try (CloseableHttpClient httpclient = HttpClients.createDefault()) { HttpUriRequest request = RequestBuilder.get() .setUri(“https://jsonplaceholder.typicode.com/todos/1”) // adding headers .setHeader(HttpHeaders.CONTENT_TYPE, “application/json”) .setHeader(“Authorization”, “Bearer 123token”) .build(); System.out.println(“Executing GET request…”); HttpResponse response = httpclient.execute(request);…

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<dependency> <groupid>org.apache.httpcomponents</groupid> <artifactid>httpclient</artifactid> <version>4.5.13</version> </dependency> import org.apache.http.HttpHeaders; import org.apache.http.HttpResponse; import org.apache.http.client.methods.HttpDelete; import org.apache.http.impl.client.BasicResponseHandler; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import java.io.IOException; public class Test { public static void main(String[] args) throws IOException { try (CloseableHttpClient httpclient = HttpClients.createDefault()) { HttpDelete httpget = new HttpDelete(“https://jsonplaceholder.typicode.com/todos/1”); System.out.println(“Executing DELETE request…”); HttpResponse response = httpclient.execute(httpget); System.out.println(“Status code: ” + response.getStatusLine().getStatusCode()); String…

Read More How to Execute an HTTP DELETE Request in Java (Solved!)

<dependency> <groupid>org.apache.httpcomponents</groupid> <artifactid>httpclient</artifactid> <version>4.5.13</version> </dependency> import org.apache.http.HttpHeaders; import org.apache.http.HttpResponse; import org.apache.http.client.methods.HttpPut; import org.apache.http.impl.client.BasicResponseHandler; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import java.io.IOException; public class Test { public static void main(String[] args) throws IOException { try (CloseableHttpClient httpclient = HttpClients.createDefault()) { HttpPut httpPut = new HttpPut(“https://jsonplaceholder.typicode.com/posts/1”); // specify the PUT body to send to the server as part of…

Read More How to Execute an HTTP PUT Request in Java

<dependency> <groupid>org.apache.httpcomponents</groupid> <artifactid>httpclient</artifactid> <version>4.5.13</version> </dependency> import org.apache.http.HttpResponse; import org.apache.http.entity.StringEntity; import org.apache.http.client.methods.HttpPost; import org.apache.http.impl.client.BasicResponseHandler; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import java.io.IOException; public class Test { public static void main(String[] args) throws IOException { try (CloseableHttpClient httpclient = HttpClients.createDefault()) { HttpPost httpPost = new HttpPost(“https://jsonplaceholder.typicode.com/posts”); // specify the POST body to send to the server as part of…

Read More Execute an HTTP POST Request in Java

<dependency> <groupid>org.apache.httpcomponents</groupid> <artifactid>httpclient</artifactid> <version>4.5.13</version> </dependency> import org.apache.http.HttpResponse; import org.apache.http.client.methods.HttpGet; import org.apache.http.impl.client.BasicResponseHandler; import org.apache.http.impl.client.CloseableHttpClient; import org.apache.http.impl.client.HttpClients; import java.io.IOException; public class Test { public static void main(String[] args) throws IOException { try (CloseableHttpClient httpclient = HttpClients.createDefault()) { HttpGet httpget = new HttpGet(“https://jsonplaceholder.typicode.com/todos/1”); System.out.println(“Executing GET request…”); HttpResponse response = httpclient.execute(httpget); String responseBody = new BasicResponseHandler().handleResponse(response); System.out.println(“Response: ” +…

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import java.util.regex.Matcher; import java.util.regex.Pattern; public class Test { public static void main(String[] args) { Pattern p = Pattern.compile(“.d”); // . (DOT) is for single character Matcher matcher = p.matcher(“zd”); System.out.println(matcher.matches()); } } Output: true   Here we specified regex for a word with two characters, and the second must be d. And since we passed…

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public class GenericClass <T> GenericClass<Type> obj = new GenericClass<Type>(); List<String> list = new ArrayList<>(); Map<Integer, String> map = new HashMap<>(); Set<String> set = new HashSet<>(); public class Test <T> { private T data; public Test(T data) { this.data = data; } public static void main(String[] args) { Test<Integer> test1 = new Test<>(10); Test<String> test2 =…

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public class TestMultithreading extends Thread { public void run() { System.out.println(“The thread is running…”); } public static void main(String args[]) { TestMultithreading test = new TestMultithreading(); test.start(); } } Output: The thread is running…   Get the id and name of a thread public class TestMultithreading extends Thread { public void run() { System.out.println(“ID: “…

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import java.io.Serializable; public class User implements Serializable { transient int userId; String name; public User(int userId, String name) { this.userId = userId; this.name = name; } } import java.io.* public class Test { public static void main(String args[]) { try { User user1 = new User(15, “Ryan”); //Write the object in a stream FileOutputStream outputStream…

Read More Transient Keyword in Java (Explained!)

import java.io.Serializable; public class User implements Serializable { int userId; String name; public User(int userId, String name) { this.userId = userId; this.name = name; } } import java.io.FileOutputStream; import java.io.ObjectOutputStream; public class Test { public static void main(String args[]) { try { User user1 = new User(15, “Ryan”); //Write the object in a stream FileOutputStream…

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public void printData(int data) { System.out.println(data); printData(data); } public static void printData(int data) { if (data > 0) { System.out.println(data); printData(–data); } } Output: 5 4 3 2 1 public class Test { public static void main(String[] args) { System.out.println(factorial(5)); } static int factorial(int num) { if (num == 1) { return 1; } else…

Read More What is Recursion in Java?

class ClassA implements Cloneable { private int someNum; private ClassC nestedObjectReference; @Override public Object clone() throws CloneNotSupportedException { ClassA classA = (ClassA) super.clone(); // with this, we are ensuring that deep copy will be performed classA.setNestedObjectReference((ClassC) this.nestedObjectReference.clone()); return classA; } // constructor, getters and setters } class ClassC implements Cloneable { private String classData; public…

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