# Chapter 4b - If Else

## Conditional Structure​ ### If Else​

``public class Main {  public static void main(String[] args) {    if(false){      System.out.println("Is True");    }else {      System.out.println("Is False");    }  }}``
🧪 Try the code out~!

##### Practice
• What do you think the program will be printing if we change `false` to `true` in `line 3`?

### Using Comparisons to resolve If Else conditionals​ ``class Main{ public static void main (String args[]){    int my_age    = 21;    int age_marie  = 25;        if(my_age < age_marie){       System.out.println("I am Younger than Marie");     }else if(my_age > age_marie){       System.out.println("I am Older than Marie");     }   }}``
🧪 Try the code out~!
##### Comparison Operators
Comparison OperatorDefinitionExample
`==`Equals2==2 -> True, 2==4 -> False
`!=`Not Equal2!=3 -> True, 2!=2 -> False
`>`Larger3>2 -> True
`<`Smaller4 < 5 -> True
`>=`Larger or Equals4 >= 2 -> True, 2>=2 -> Tru

### Else IF​

##### note ``public class Main {  public static void main(String[] args) {        int age = 17;    if(age == 17){      System.out.println("Age is 17");    }else if(age>17) {      System.out.println("You are an adult now");    }else{      System.out.println("You are still a kid.");    }  }}``

Explaination:

``If (Boolean condition1) Then    (perform computation or action)Else if (Boolean condition2) Then    (perform another computation or action)Else    (perform a default computation or action)``
🧪 Try the code out~!

##### Exercise

👀 Exercise in the curriculum

Complete the following program so that it prints if number is positive or not.

• If the input is positive it should print: `num is positive.`
• else If the input is negative it should print: `num is negative`
• else (the case where input is neither positive or negative) it should print: `num is ZERO (0)`

🙋‍♀️ Sample expected program:

• Try entering `5`
• Try entering `-5`
• Try entering `0`

### Nested Conditionals​

👀 Curriculum - Nested Conditionals

``public class Main{ public static void main(String args[]){  int num = 25;   if (num >5){   System.out.println("num is greater than 5");   if(num>10){      System.out.println("num is larger than 10");      if(num>20){        System.out.println("num is larger than 20");             }   }  }else if(num<0){      System.out.print ("num is negative");      }else{    System.out.print ("num is ZERO (0)");  } }}``