Java Language

Internal

• Java

Lexical Structure

Keywords

• synchronized. See synchronized statement and synchronized modifier.
• static. See class variables.

Statements

synchronized

The synchronized statement acquires a mutual-exclusion lock on behalf of the executing thread, executes a block, then releases the lock. While the executing thread owns the log, no other thread may acquire the lock.

synchronized (expression) block

The type of expression must be a reference type.

Also see:

'synchronized' mechanism

Modifiers

Method Modifiers

synchronized

A synchronized class method synchronizes on the monitor associated with the Class object of that class.

A synchronized instance method synchronizes on the monitor associated with this - the object instance it is invoked onto.

Also see:

'synchronized' mechanism

Types

Java is a statically typed language, which means that every variable and every expression has a type that is known at compile time.

Java is strongly typed language, because the types limit the values a variable can hold or that an expression can produce, limit the operations supported by those types and determine the meaning of operations.

Reference Types

There are four kinds of reference types: class types, interface types, type variables and array types.

Variables

A variable is a storage location and has an associated type - the compile-time type - that is either a primitive type or a reference type.

The value of a variable is changed by an assignment or by a prefix/postfix increment/decrement operators.

There are eight kinds of variables:

Class Variable

A class variable is a field declared using the keyword static within a class declaration, or with or without the keyword static within an interface declaration.

Instance Variable

An instance variable is a field declared within a class declaration without using the keyword static.

Array Component

Array components are unnamed variables that are created and initialized to default values whenever a new object that is an array is created.

Method Parameter

Method parameters

Interface

An interface groups related methods together into a contract.

Class

Anonymous Class

Can be used for behavior parameterization.