The syntax of Java is the set of rules defining how a Java program is written and interpreted. The syntax is mostly derived from C and C++. Unlike in C++, in Java there are no global functions or variables, but there are data members which are also regarded as global variables. All code belongs to classes and all values are objects. The only exception is the primitive types, which are not represented by a class instance for performance reasons (though can be automatically converted to objects and vice versa via autoboxing). Some features like operator overloading or unsigned integer types are omitted to simplify the language and to avoid possible programming mistakes. The Java syntax has been gradually extended in the course of numerous major JDK releases, and now supports capabilities such as generic programming and function literals (called lambda expressions in Java). Since 2017, a new JDK version is released twice a year, with each release bringing incremental improvements to the language. Basics Identifier An identifier is the name of an element in the code. There are certain standard naming conventions to follow when selecting names for elements. Identifiers in Java are case-sensitive. An identifier can contain: Any Unicode character that is a letter (including numeric letters like Roman numerals) or digit. Currency sign (such as ¥). Connecting punctuation character (such as _). An identifier cannot: Start with a digit. Be equal to a reserved keyword, null literal or boolean literal. Keywords Literals Integer literals are of int type by default unless long type is specified by appending L or l suffix to the literal, e.g. 367L. Since Java SE 7, it is possible to include underscores between the digits of a number to increase readability; for example, a number can be written as . Variables Variables are identifiers associated with values. They are declared by writing the variable's type and name, and are optionally initialized in the same statement by assigning a value. int count; //Declaring an uninitialized variable called 'count', of type 'int' count = 35; //Initializing the variable int count = 35; //Declaring and initializing the variable at the same time Multiple variables of the same type can be declared and initialized in one statement using comma as a delimiter. int a, b; //Declaring multiple variables of the same type int a = 2, b = 3; //Declaring and initializing multiple variables of the same type