Hello World Program
public class MyClass {
public static void main(String[] args) {
System.out.println('Hello World');
}
}
Comments in Apex
// This is Single Line Comment
/* This is Multiple Line Comment */
Primitive Data Types
// Syntax: <dataType> <variableName> = <value>;
String authorName = 'Syahmi Fauzi';
Integer age = 20;
Boolean isApexFun = true;
Double piValue = 3.141592653589793238;
Long randomLongNumber = 8748693648L;
ID id='00300000003T2PGAA0';
Non-Primitive Data Types
String, Arrays, and Classes
Operators in Apex
| Type | Operators |
|---|---|
| Arithmetic | +, -, *, /, %, ++, -- |
| Assignment | =, +=, -=, *=, /=, %=, &=, etc |
| Comparison | ==, !=, >, <, >=, <= |
| Logical | &&, ||, ! |
| Bitwise | ^, &, | |
Useful String Methods
String text = 'Hello World';
System.debug(text.length); // 11
System.debug(text.toUpperCase); // HELLO WORLD
System.debug(text.indexOf('World')); // 6
System.debug(text.contains('Hello')); // true
System.debug(text.charAt(0)); // 72
System.debug(text.endsWith('friend')); // false
System.debug(text.indexOf('Apex')); // -1
See Apex Reference Guide for more on String methods.
Useful Math Methods
System.debug(Math.min(2, 3));
System.debug(Math.max(2, 3));
System.debug(Math.sqrt(36));
System.debug(Math.abs(-32));
System.debug(Math.random());
Conditional Statements
if, else if, else
Integer age = 20;
if (age < 15) {
System.debug('Too young');
} else if (age <= 20) {
System.debug('Welcome to the club');
} else if (age <= 40) {
System.debug('You still can join us');
} else {
System.debug('Sorry, you can\'t join us');
}
Note: Curly braces is optional if there is only one statement in the code block.
ternary operator
Boolean isFun = true;
String message = isFun ? 'You are having fun' : 'Not fun at all';
Loops in Apex
for loop
List<String> fruits = new List<String>{'apple', 'orange', 'grape'};
for (Integer i = 0; i < fruits.size(); ++i) {
System.debug(fruits[i]);
}
for each loop
List<String> fruits = new List<String>{'apple', 'orange', 'grape'};
for (String fruit : fruits) {
System.debug(fruit);
}
while loop
// How many times `num` can be divided by 2 before it is less than or equal to 1?
Integer times = 0;
Integer num = 17;
while (num > 1) {
num /= 2;
++times;
}
System.debug(times + ' times'); // 4 times