jdk consists of a compiler. converts your written code into byte code
In order to get your code running in java, you need a main method
You need the function public static void main(String[] args){} for your program to run
Most statements will end with a semicolon
To console log in java, do System.out.print();
To print with a new line, do System.out.println(); adds a new line after printing to console
You can also do \n, has the functionality. Ie. “Hello world \n”
Single line comments is //
Multi line comments is /* */
Primitive data type - simple value directly in memory (stack)
Reference data type - memory address (stack) that points to the (heap)
- Primitive - int, double, char, boolean
- Reference - array, object, string
Declaration of variable is int age;
Assignment of variable is int age = 28;
Truthy falsy values still apply
Scanner is an object accepts user input in java
To use this, we have to import it using import java.util.Scanner; (scanner is a class)
To initialize the scanner object, use Scanner scannerObjName = new Scanner(System.in);
To accept an input from a user, use the scanner object you initialized ie. scannerObjName.nextLine();
If you don’t want any spaces to be included from the input, use scannerObjName.next(); instead.
For example, if the user inputs hatsune miku, you will only receive hatsune
If you use nextInt(), nextDouble(), nextBoolean(), next(), and then nextLine() (note this does not apply to next()), you need to do nextLine() right after (if you do next(), you will receive an error). Otherwise it will not function as intended and it will ignore the next input.
Bad example:
int age = scannerObjName.nextInt();
scannerObjName.next();
System.out.println("enter your name");
String name = scannerObjName.nextLine();
Bad example:
System.out.println("enter your age");
int age = scannerObjName.nextInt();
scannerObjName.nextLine();
System.out.println("enter your name");
String name = scannerObjName.next();
Good example:
System.out.println("enter your age");
int age = scannerObjName.nextInt();
scannerObjName.nextLine();
System.out.println("enter your name");
String name = scannerObjName.nextLine();