JAVA

Java 8

There are dozens of features added to Java 8, the most significant ones are mentioned below −

• Lambda expression − Adds functional processing capability to Java.
• Method references − Referencing functions by their names instead of invoking them directly. Using functions as parameter.
• Default method − Interface to have default method implementation.
• New tools − New compiler tools and utilities are added like 'jdeps' to figure out dependencies.
• Stream API − New stream API to facilitate pipeline processing.
• Date Time API − Improved date time API.
• Optional − Emphasis on best practices to handle null values properly.
• Nashorn, JavaScript Engine − A Java-based engine to execute JavaScript code.

Java SE 8 Interview Questions and Answers

• Java SE 8 Interview Questions and Answers - 1

Java Ubuntu

$ sudo update-alternatives --config java
[sudo] password for rasimsen: 
There are 2 choices for the alternative java (providing /usr/bin/java).

  Selection    Path                                            Priority   Status
------------------------------------------------------------
* 0            /usr/lib/jvm/java-11-openjdk-amd64/bin/java      1111      auto mode
  1            /usr/lib/jvm/java-11-openjdk-amd64/bin/java      1111      manual mode
  2            /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java   1081      manual mode

Press <enter> to keep the current choice[*], or type selection number: 2
update-alternatives: using /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java to provide /usr/bin/java (java) in manual mode


rasimsen@workspace:~/workspace$ java -version
openjdk version "1.8.0_242"
OpenJDK Runtime Environment (build 1.8.0_242-8u242-b08-0ubuntu3~18.04-b08)
OpenJDK 64-Bit Server VM (build 25.242-b08, mixed mode)

https://www.digitalocean.com/community/tutorials/how-to-install-java-with-apt-on-ubuntu-18-04