Identifiers and Keywords in Java

Java shares a common look and feel with C. C++ and Java syntax are similar.

There are three types of comments in Java.

• // is a one line comment
• /* ... */ can enclose single or multiline comments
• /** ... */ are special doc comments which are detected by the JavaDoc utility. Doc comments are usually placed before method declarations

/* This is the main method
and this is a multi-line comment */

public static void main (String args[])
{
	boolean completed = false;
	int i = 1, j = 1; // an in-line comment
	int anArray[] = new int[25];

	/* a single line comment */

	if ( ! finished )
	{
		i++;
		j += i;
		returnVal = anArray[j];
	}
}

The Java compiler ignores white space and comments and is parsed into tokens by the compiler. Tokens are the lowest level elements recognised by the compiler. Tokens are made of of the following elements.

• Literals are converted to strings.
• Identifiers are user defined elements such as variables. One should give explicit meanings to the names of identifiers. This will allow those after you to understand your code more easily. Note that identifiers are case sensitive in Java. Recommendations for the naming of identifiers are listed as follows.
  
  
  • Use all lowercase except for the first character of embedded words, for example, anInteger, aString.
  • The first letter is lowercase.
  • Separating words with the _ character is a commonly used convention.
  
  
• Keywords are reserved by the compiler. Keywords have a specific meaning to the compiler.
• Operators operate on other tokens such as the addition operator (+) which can be used to add the contents of two variables.

Java Keywords