What is the default value of variable?
When variable is of any class type (non-primitive type), then it is known as reference variable, and it contains null value as a default value.
Do Java variables have default values?
The local variables do not have any default values in Java. This means that they can be declared and assigned a value before the variables are used for the first time, otherwise, the compiler throws an error.
How are variables initialized by default in Java?
Each class variable, instance variable, or array component is initialized with a default value when it is created (§15.9, §15.10): For type byte, the default value is zero, that is, the value of (byte)0. For type short, the default value is zero, that is, the value of (short)0.
What is the default value for a class object?
null
The default value for classes is null . For structures, the default value is the same as you get when you instantiate the default parameterless constructor of the structure (which can’t be overriden by the way). The same rule is applied recursively to all the fields contained inside the class or structure.
What is the default value in Java?
Default Values
| Data Type | Default Value (for fields) |
|---|---|
| int | 0 |
| long | 0L |
| float | 0.0f |
| double | 0.0d |
How do I set default value in Java?
Remember, to get the default values, you do not need to assign values to the variable. static boolean val1; static double val2; static float val3; static int val4; static long val5; static String val6; Now to display the default values, you need to just print the variables.
What is a class variable in Java?
In object-oriented programming with classes, a class variable is a variable defined in a class of which a single copy exists, regardless of how many instances of the class exist. A class variable is not an instance variable. It is a special type of class attribute (or class property, field, or data member).
Which variable type has default value automatically?
Variable Categories There are three distinct types of variables that are automatically initialized with a default value based on their type. Except for reference types, which are initialized with null , the rest are initialized with a value provided by their default constructor.
What is the default value of an int in Java?
0
The line System. out. println(a); will be an error pointing at the variable a that says variable a might not have been initialized whereas in the given reference, integer will have 0 as a default value.
How do you assign a value to a class variable in Java?
To access class variables, you use the same dot notation as with instance variables. To retrieve or change the value of the class variable, you can use either the instance or the name of the class on the left side of the dot.
How do I set default value?
Set a default value Right-click the control that you want to change, and then click Properties or press F4. Click the All tab in the property sheet, locate the Default Value property, and then enter your default value.
How do you assign default values to variables?
The OR Assignment (||=) Operator The logical OR assignment ( ||= ) operator assigns the new values only if the left operand is falsy. Below is an example of using ||= on a variable holding undefined . Next is an example of assigning a new value on a variable containing an empty string.
Can we initialize variable in class in Java?
In Java, you can initialize a variable if it is a member of the class. There are four ways to initialize members of the class data: initialization by default (implicit initialization); explicit initialization with initial values (constant values);
What is Java class initialization?
A Class is initialized in Java when : 1) an instance of the class is created using either a new() keyword or using reflection using class. forName(), which may throw ClassNotFoundException in Java. 2) a static method of a class is invoked. 3) a static field of Class is assigned.
What is the default data type in Java?
Int Data Type Its default value is 0. The int data type is generally used as a default data type for integral values unless if there is no problem about memory. Example: int a = 100000, int b = -200000.
Which variables are initialized automatically?
There are three distinct types of variables that are automatically initialized with a default value based on their type.
- Static variables.
- Instance variables of class instances.
- Array elements.
- Reference type (a.k.a. pointer)
How do you initialize a variable in Java?
The syntax for an initializer is the type, followed by the variable name, followed by an equal sign, followed by an expression. That expression can be anything, provided it has the same type as the variable. In this case, the expression is 10, which is an int literal.
What is a Java class variable?
Class variables − Class variables also known as static variables are declared with the static keyword in a class, but outside a method, constructor or a block. There would only be one copy of each class variable per class, regardless of how many objects are created from it.
What is the default value of variable in JavaScript?
undefined
Setting JavaScript default parameters for a function In JavaScript, a parameter has a default value of undefined. It means that if you don’t pass the arguments into the function, its parameters will have the default values of undefined .