What occurs when object is created in Java?

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My teacher gave me a question:

"What occurs when objects are created in Java".

To the best of my knowledge, memory allocation, variable initialization and constructor method invocation happen when an object is created.

But my teacher said that I was almost right. The 2 later things are right, except memory heap. Instead, he said the memory allocation occurs. I think that object is stored in heap, so my teacher is wrong. Do you think so?

As always, the best place to find a solution for these kinds of questions is in the Java Language Specification.

Specifically, from the section on new instance creation, it can be understood that this is the sequence when a new object is created, as long as no exceptions occur:

  1. Memory is allocated.
  2. Fields are initialized to their default values.
  3. The "first line" of the chosen constructor is invoked, unless it's an Object. By first line I mean either explicit call to super() or this(), or an implicit call to super().
  4. The instance initializer is executed and the fields are initialized to their requested values (actually field initialization is usually compiled as an inline part of the instance initializer).
  5. The rest of the constructor code is executed.

Now, it is possible that your teacher is talking about memory allocation as an actual operating system call - and in that case he's right in the sense that the JVM manages its own heap and thus a Java memory allocation does not necessarily translate to an OS memory allocation call (although it may).

Object Lifecycle, All objects in Java programs are created on heap memory. An object is created based on its class. You can consider a class as a blueprint, template, or a  The instance variables of the objects are initialized to their default values. 3. The constructor for the most derived class is invoked. The first thing a constructor does is call the constructor for its uppercase. This process continues until the constructor for java.lang.Object is called, as java.lang.Object is the base class for all objects in java.

I'll answer that using a simple example.

Say you have a class Car. Now you write:

Car car;
car = new Car();

The first statement creates a reference with car in the stack.

In the second statement, the Car class will be loaded to the main memory, then it will allocate memory for the members of Car in the heap. When this happens, the members will be initialized with values provided by the JVM.

Creating Objects (The Java™ Tutorials > Learning the Java , Creating Objects. As you know, a class provides the blueprint for objects; you create an object from a class. Each of the following statements taken from the  Declaration: The code set in bold are all variable declarations that associate a variable name with an object type. Instantiation: The new keyword is a Java operator that creates the object. Initialization: The new operator is followed by a call to a constructor, which initializes the new object. Declaring a Variable to Refer to an Object

While the JVM is running the program, whenever a new object is created, the JVM reserves as portion of the Heap for that object (where the object will be stored). The amount of Heap that gets reserved is based on the size of the object.

The JVM maps out this segment in the Heap to represent all of the attributes of the object being stored. A reference (address in Heap) to the object is kept by the JVM and stored in a table that allows the JVM to keep track of all the objects that have been allocated on the Heap. The JVM uses these references to access the objects later (when the program accesses the object).

Describe what happens when an object is created in Java , Memory is allocated from heap to hold all instance variables and implementation-​specific data of the object and its superclasses. Implementation-specific data  The constructor for the most derived class is invoked. The first thing a constructor does is call the constructor for its super classes. This process continues until the constructor for java.lang.Object is called, as java.lang.Object is the base class for all objects in java.

On top of what other people have said, if this is the first use of the object then its Class must be initialised -as described in the JLS (the section before the one on new instance creation!).

This basically involves loading into memory the necessary information about the class i.e. creating a Klass object for the static variables and method table to live. This may also involve loading super classes and interfaces. This is all carried out by the ClassLoader.

Java - Object and Classes, In Java, the new keyword is used to create new objects. There are three steps when creating an object from a class −. Declaration − A variable declaration with a  There is one class created for each type of Java class. All objects in Java programs are created on heap memory. An object is created based on its class. You can consider a class as a blueprint, template, or a description how to create an object. When an object is created, memory is allocated to hold the object properties.

When object is created in java then these 6 step will be happens one by one--- 1.JVM allocates 8 bytes of memory for the reference variable & assign default value as null.

  1. JVM will verify whether class loading is done or not,if class is already loaded then it will ignore or else it will perform class loading.
  2. At the time of class loading ,if any static variable are there then it will allocating memory.
  3. By using new operator,object memory will e created inside heap memory.
  4. At the time of object creation,if any instance variables are there then those will allocate memory inside object Memory.
  5. It will assign object memory address to the reference variable which is created first.

Creating Objects, Creating Objects. In Java, you create an object by creating an instance of a class or, in other words, instantiating a class. You will learn  Java 2 Chapter 9. STUDY. Flashcards. Learn. Write. Spell. Test. PLAY. Match. Gravity. Created by. rnice01. Terms in this set (62) anonymous object. an object created

Working with Objects in Java | Creating New Objects, Instantiation: The new keyword is a Java operator that creates the object. As discussed below, this is also known as instantiating a class. Initialization: The new  A) Constructors are invoked using the new operator when an object is created. B) Constructors must have the same name as the class itself. C) At least one constructor must always be defined explicitly. D) A default no-arg constructor is provided automatically if no constructors are explicitly declared in the class.

Describe What Happens When an Object is Created in Java, Learn how to create objects, test and modify their class and instance and it needs them, an error occurs when the program is compiled. 8) Java allows you to create objects of this class in the same way you would create primitive variables. 9) A UML diagram does not contain: A) the class name. B) the method names. C) the field names. D) object names. 10) Data hiding, which means that critical data stored inside the object is protected from code outside the.

The Life Cycle of a Java Object, Implementation-specific data includes pointers to class and method data. 2. The instance variables of the objects are initialized to their default  Till now you have five String objects, four in String Constant Pool and one in Heap. So your str4 is a new object altogether inside the String Pool, Please check the below code also, String str5="HelloWorld"; //This line will create one more String Constant Pool object because we are using variable name as str5.