Simple Program :- Hello Java Example
In this page, we will learn how to write the hello java program. Creating hello java example is too easy. Here, we have created a class named Simple that contains only main method and prints a message hello java. It is the simple program of java.
Requirement for Hello Java Example
For executing any java program, you need to
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Syntax
of defining a class –
class Identifier
{
Members definition
}
NAMING CONVENTIONS OF JAVA
- First letter of each word of a class name is
capitalized.
Example
String
StringBuffer
ArrayIndexOutOfBoundException
etc.
- In case of methods first letter of each word
except the first word is capitalized.
Example
printf()
getPriority()
getKeyMethodMap()
etc.
·
Functions (in
C or C++) represents an operation which can be independent whereas methods
represents behavior which cannot be independent.
Functions
(Task)
|
Methods
(Behaviour)
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deposit( )
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a.deposit(5000);
b.deposit(7000);
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What is happening
Way of doing things
|
What is happening
Who is doing.
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Question : Why in Java’s main method return type void is
used?
Figure 1 is compiler-based program which directly calls O/S
functions during execution. So, here O/S returns some integer value to
acknowledge that whether the application run successfully or not.
Figure 2 is interpreter-based program which is executed by
JRE. Java application has no direct connectivity with O/S. It runs on JRE.
It is JRE who confirms that all byte codes are valid and do not violate
Java’s security restrictions. Any type of rule violation led to error(Compile
time or runtime) by JRE.
Since JRE is boss of everything and itself capable
to handle each type of error, it doesn’t expect anything to come back from
main(), so we use void in main() method.
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