Page 14 - DCAP501_Modern Programming Tools and Techniques I

Unit 1: Introduction to Java

Interpretation

At the command line on UNIX and DOS shell operating systems, the Java interpreter is invoked as
follows:
java ExampleProgram
Running

At the command line, you should see the output that is given within the System.out.println statement in
the program.
I am a simple program

Write a simple Java program to print “Java”.

1.3 Keywords
Keywords are predefined identifiers set aside by Java for a particular purpose. These keywords cannot
be used as names for variables, classes, methods or as identifiers or tokens. All keywords must be
written in lowercase letters. At present, there are fifty defined keywords in the Java language. Table 1.2
gives a list of the Java keywords.

Table 1.2: Keywords in Java

abstract Continue assert default Boolean

do Double byte else case
enum Catch extends char final
class Finally const float for
goto If implements import instanceof
int Interface long native new
package Private protected public return
short Static strictfp super switch
synchronized This throw throws transient
try Void volatile break while

The keywords in Java have a predefined meaning and they perform distinct functions. Some of the
keywords and their functions are listed below:
1. abstract: This Java keyword is used for declaring a method without providing that method’s
implementation, in a method declaration.
2. assert: This Java keyword is used for making a condition’s assumed value explicit.
3. boolean: This Java keyword is used for relating to an expression or variable, which can have only
either a true or false value.

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