Oracle Certification Associate 1Z0-808: Difference between revisions
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Revision as of 17:57, 4 June 2020
Links
Installation
Windows
<source lang="Shell"> C:\Program Files\Java </source>
- Java Se Development Kit 8
- Java FX SDK
- Private JRE - Java Runtime Edition
- Java Mission Control Tools
Can also be installed:
- Development Tools
- Source Code
- Public JRE
Linux
<source lang="Shell"> sudo apt-get install oracle-java8-installer cd /usr/lib/jvm/java-8-oracle
- Java version
java -v
- Java Compiler
javac -version </source>
Basics
Main Method
<source lang="Java"> public static void main(String[] args]) </source>
Comments
<source lang="Java"> // Single Line Comment
/* Multi Line Comment
- /
/**
* Java Doc Comment * @param * @return */
</source>
Import Conflicts
<source lang="Java"> import java.util.*; import java.sql.*;
// ==> in code = COMPILATION error Date date; </source>
Static Imports
It is not a good idea to do static imports a lot in a projet because it makes difficult to understand where the methods / constants come from
- Static imports are for importing static members
- Classic imports are for importing classes
it can be used for methods and constants for example <source lang="Java"> import static java.lang,Math.*;
// Instead of typing Math.min(1,2); we can just type min(1,2) // Because of the static import </source>
Primitives
KeyWord | Size | Examples | Smallest Data-Type | ||
---|---|---|---|---|---|
Boolean | - | true | |||
Numbers without decimal points | |||||
byte | 8-bits | 1 | |||
short | 16-bits | 12 | comment | ||
int | 32-bits | 100 | Default all numbers in Java | ||
long | 64 bits | 12 | |||
float | 32-bits | 123.45 | Requires letter "f" following the numbers | ||
double | 64-bits | 123.45 | Default all primitives or all that similar types | ||
char | 16-bits | 'a' |