LINUX

mv - is used to move or rename files and directories
rm - is used to delete files permanently
uname - is used to display system information
locate - is used to find files using a database
touch - is used to create empty files and updates file timestamps
ln - is used to create links between files
clear - is used to clear the terminal screen
ps - is used to display running processes

JAVA

  • Java is platform independent Language
  • Java stores file as bytecode, which helps to run the same file in different OS, make it platform independent
  • JDK converts into bytecode (.class files) and JIT converts it into Binary code for machine understandable language, after conversion its handled by JVM.
  • All these process runs in JRE [ Java Runtime Environment ]
  • toString() is a method used to convert objects into that data type. 
# Print an Array using For loop public class Array { public static void main(String[] args) { int[] array = {1, 2, 3, 4, 5}; for (int element: array) { System.out.println(element); } } } # Print an Array using standard library Arrays import java.util.Arrays; public class Array { public static void main(String[] args) { int[] array = {1, 2, 3, 4, 5}; System.out.println(Arrays.toString(array)); } }

SPRINGBOOT

SQL

DDL – Data Definition Language

Used to define and modify database structures.

CREATE → Create tables, databases, indexes, views.

ALTER → Modify existing database objects.

DROP → Delete database objects.

TRUNCATE → Remove all records from a table (faster than DELETE).

RENAME → Change the name of a database object.

👉 Example:

CREATE TABLE Students ( StudentID INT PRIMARY KEY, Name VARCHAR(50), Age INT );

Reference

https://www.programiz.com/java-programming/examples/print-array
https://www.geeksforgeeks.org/java/difference-between-spring-and-spring-boot/
https://www.w3schools.com/JAVA/ref_string_tostring.asp