Words used in programs to name classes, variables, methods, or labels are called identifiers . These need to comply with certain rules. An identifier cannot be a Java reserved word . An identifier can begin with a letter, a dollar sign, or an underscore character only . Any subsequent character of an identifier can be a letter, a digit, a dollar sign, or an underscore only .
Identifiers are case-sensitive .
Flow control is an essential part of a programming language and Java is no exception to it. It provides you with various ways to control the flow of your program. Java allows only boolean expressions to be used as condition . Two of the commonly used loops are the for and while loops. That is, it's not available after the loop.