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Java Articles
Page 148 of 450
How to convert an OutputStream to a Writer in Java?
Input and output Streams in Java are objects that accepts sequence of information and sends them further. These are used to read and write data from/to various sources.What are Output Streams & WritersA Java output streams accept output data (bytes) from a source and sends it to the destination. An output stream is represented by an abstract class known as OutputStream. This is the super class of all the OutputStream classes. There are various output streams in Java namely, ByteArrayOutputStream, FileOutputStream, FilterOutputStream, ObjectOutputStream, PipedOutputStream.Writers are objects that are used to write data to character streams. These are represented by the abstract ...
Read MoreHow can we avoid a deadlock in Java?
This article explains several strategies to avoid deadlock in Java, including a brief introduction to deadlock, strategies, and respective examples. Deadlock in Java In case of multi-threading, a deadlock is a programming situation where two or more threads are holding resources needed by other threads and are blocked forever, waiting for each other (to release the required resource). A deadlock condition will occur with at least two threads and two or more resources.How To Avoid Deadlock in Java? Following is a list of strategies to avoid the deadlock in Java: ...
Read MoreCan we define multiple methods in a class with the same name in Java?
Yes, we can define multiple methods in a class with the same name. But if we have two methods with the same name, the compiler should be able to differentiate between the two methods. Therefore, in Java, "we can define multiple methods" with the same name in a single class, as long as each method has a different set of parameters. When we invoke a method, the compiler executes the respective body (code) based on the arguments passed.This concept is known as method overloading. Method Overloading in Java In Java, method overloading is a type of compile-time polymorphism. Polymorphism is one ...
Read MoreHow can we print all the capital letters of a given string in Java?
The Character class is a subclass of the Object class, and it wraps a value of the primitive type char in an object. An object of type Character class contains a single field whose type is char. We can print all the capital letters of a given string using the following approaches - Using isUpperCase() Method Using ASCII Comparison Using isUpperCase() Method The isUpperCase() is the method of the Character class. It accepts a character as a parameter and returns true if it is an uppercase letter and false if not.To ...
Read MoreHow to check the memory used by a program in Java?
This article will discuss "how to check the memory used by a program" in Java, including a brief introduction of the process for calculation and an appropriate example that correctly checks the memory usage by the program. Understanding Memory Usage in Java Programs A Java code that takes a long time to execute, makes heavy use of dynamic memory. In such scenarios, we may end up with Out-of-Memory errors (due to a memory shortage of the heap space). We can calculate the memory space (heap) used by a Java program using the methods provided by the Runtime class.If the heap space is ...
Read MoreHow to access the JSON fields, arrays and nested objects of JsonNode in Java?
What are JSON and JsonNode? JSON is a format that is used to store data and exchange data between a server and a client. To know more about JSON, you can refer to the JSON Tutorial. A JsonNode is Jackson's tree model for JSON. To read JSON into a JsonNode with Jackson by creating an ObjectMapper instance and call the readValue() method. We can access a field, array or nested object using the get() method of the JsonNode class. We can return a valid string representation using the asText() method and ...
Read MoreHow to serialize a null field using Gson library in Java?
Gson is a library in the Java that is mainly used for converting Java objects to JSON and vice versa. By default, the Gson object does not serialize the fields with null values to JSON. If a field in a Java object is null, Gson excludes it.Serializing a Null Field Using Gson We can force Gson to serialize null values via the GsonBuilder class. We need to call the serializeNulls() method on the GsonBuilder instance before creating the Gson object. Once serializeNulls() has been called, the Gson instance created by the GsonBuilder can include null fields in the serialized JSON. ...
Read MoreHow to deserialize a JSON into an existing object in Java?
Deserialization is the process of converting a JSON string into a Java object. In this example, we will learn how to deserialize a JSON string into an existing object in Java. There are libraries available in Java that can help us to deserialize a JSON string into an existing object. Some of the popular libraries are: Using Gson Using Jackson Using Flexjson Let's learn how to use each of these libraries to deserialize a JSON string into an existing object in Java. Deserializing JSON Object Using ...
Read MoreDifferences between fromJson() and toJson() methods of Gson in Java?
Gson is a Java library which is developed by Google and used to convert Java objects into JSON and vice versa. It is mostly used in applications where data can be exchanged in JSON format. There are two useful methods in Gson that we are going to discuss in this article. These methods are fromJson() and toJson(). The fromJson() Method The fromJson() method is used to convert a JSON string into a Java object. It takes two parameters: the JSON string and the class type of the object you want to create. Here is the syntax of the fromJson() method: ...
Read MoreHow to serialize a map using the flexjson library in Java?
Serializing a Map in Java is the process of converting a Map object into a format that can be easily stored or transmitted, such as JSON or XML. We will use the Flexjson library to serialize a map in Java. We can serialize a Map using the serialize() method of the JSONSerializer class, which performs a shallow serialization of the target instance. Example of Serializing a Map We will take a map and see the output after serialization. Map map = new HashMap(); map.put("name", "Ansh"); map.put("age", "23"); map.put("city", "Mumbai"); map.put("country", "India"); After serialization, the map will look like this: {"name":"Ansh", ...
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