// eg1
// user input > 100?
import java.util.Scanner;

// 3 blocks
// 1 class definition / define class
// 2 define 'main' method
// 3 within 'condition clause'
public class Example {
    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);
        
        System.out.print("Give a number: ");
        int num = Integer.valueOf(reader.nextLine());

        if (num > 100) {
            System.out.println("Number was greater than 100.");
        }

    }
}








// eg2
// else
import java.util.Scanner;

public class Example {
    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);
        
        System.out.print("Give a number: ");
        int num = Integer.valueOf(reader.nextLine());

        if (num > 100){
            System.out.println("Number was greater than 100.");
        } else {
            System.out.println("Number was lesser than or equal to 100.");
        }
    }
}
Example output:
Give a number: 54
Number was lesser than or equal to 100.







// eg3
// else if
import java.util.Scanner;

public class Example {
    public static void main(String[] args) {
        Scanner reader = new Scanner(System.in);
        
        System.out.print("Give a number: ");
        int num = Integer.valueOf(reader.nextLine());

        if (num < 0){
            System.out.println("Number was negative.");
        } else if (num > 0) {
            System.out.println("Number was positive.");
        } else {
            System.out.println("Number was zero.");
        }
    }
}
Example output:

Give a number: 15
The number was positive.