Identifiers [painless-identifiers]

Use an identifier as a named token to specify a variable, type, field, method, or function.

:::{important} Identifiers cannot be keywords. Using a keyword as an identifier will result in a compilation error. :::

Identifiers are the names you give to elements in your code. They must follow specific naming rules and provide meaningful names that clearly describe their purpose.

Grammar

java

ID: [_a-zA-Z] [_a-zA-Z-0-9]*;

Naming rules

Must start with a letter (a-z, A-Z) or underscore (_)
Can contain letters, numbers (0-9), and underscores
Case sensitive (myVar and MyVar are different)
Cannot be a keyword

Examples

Variations of identifiers
text
```
 a      <1>
 Z      <2>
 id     <3>
 list   <4>
 list0  <5>
 MAP25  <6>
 _map25 <7>
 Map_25 <8>
```
1. int a = 10;
2. String Z = "Z";
3. String id = "user_123";
4. boolean list = true;
5. float list0 = 3.14f;
6. long MAP25 = 123456789L;
7. double _map25 = 99.99;
8. byte Map_25 = 25;

Best practices

Choose meaningful identifier names that clearly describe their purpose:

// Good: descriptive and clear
String customerEmail = "[email protected]";
int totalPrice = calculateTotal();
boolean isProductAvailable = checkInventory();

// Avoid: unclear or too short
String s = "[email protected]";
int x = calculateTotal();
boolean b = checkInventory();