ReservedKeyword: (one of)
abstract continue for new switch
assert default if package synchronized
boolean do goto private this
break double implements protected throw
byte else import public throws
case enum instanceof return transient
catch extends int short try
char final interface static void
class finally long strictfp volatile
const float native super while
_ (underscore)
ContextualKeyword: (one of)
exports opens requires uses
module permits sealed var
non-sealed provides to with
open record transitive yield
Link: Java Keywords
Writing code is similar to writing a document. It consists of special hierarchical units, which together form a whole. These are:
The Expression – An expression computes to a single value. The Statement – Statements are stand alone units of work. And Code Blocks – A code block is a set of zero, one, or more statements, usually grouped together in some way to achieve a single goal.
A method declares executable code that can be invoked, passing a fixed number of values as arguments. A method is a way of reducing code duplication. A method can be executed many times with potentially different results, by passing data to the method in the form of arguments.
This method has a name, but takes no data in, and returns no data from the method (which is what the special word void means in this declaration).
public static void methodName() {
// Method statements from method body
}To execute a method, we can write a statement in code, which we say is calling, or invoking, the method. For a simple method like calculateScore, we just use the name of the method, where we want it to be executed, followed by parentheses, and a semi-colon to complete the statement. So for this example, the calling statement would look like the code shown here:
calculateScore();Where we previously had empty parentheses after the method name, we now have method parameters in the declaration.
public static void methodName(p1type p1, p2type p2, {more}) {
// Method statements from the method body
}Parameters and arguments are terms that are often used interchangeably by developers. But technically, a parameter is the definition as shown in the method declaration, and the argument will be the value that's passed to the method when we call it.
To execute a method that's defined with parameters, you have to pass variables, values, or expressions that match the type, order and number of the parameters declared. In the calculateScore example, I declared the method with four parameters, the first; a boolean, and the other three of int data types. So we have to pass first a boolean, and then 3 int values as shown in this statement:
calculateScore(true, 800, 5, 100);I can't pass the boolean type in any place, other than as the first argument, without an error.