Language Features

General

Enhanced For Loops

Prefer enhanced for loops over index-based loops unless the index is actually needed.

script.java

for (String name : names) { // good  System.out.println(name);}for (int i = 0; i < names.size(); i++) { // only if index is needed  System.out.println(names.get(i));}

String Templating

Prefer String.format() or formatted() over string concatenation for readability.

script.java

String msg = "Hello, %s!".formatted(name); // goodString msg = "Hello, " + name + "!";       // avoid

Ternary Operator

Ternary operators are acceptable for simple, readable assignments. Do not nest ternaries.

script.java

String label = isActive ? "Active" : "Inactive";                           // goodString label = isActive ? (isPremium ? "Premium" : "Active") : "Inactive"; // bad

Switch Expressions

Prefer switch expressions (arrow syntax) over traditional switch statements for assignments.

script.java

// goodString label = switch (status) {  case ACTIVE -> "Active";  case PENDING -> "Pending";  default -> "Unknown";};// avoidString label;switch (status) {  case ACTIVE:    label = "Active";    break;  ...}

Optional

Prefer Optional<T> for return values that may be absent instead of returning null.
This helps programmers understand your functions and avoid silent null returns.

script.java

public Optional findUser(String id) { // good  ...}public User findUser(String id) {     // avoid if findUser() could return null  ...  if (userNotFound) {    return null;  }}

Do not use Optional as a method parameter or field, only as a return type.

script.java

public void process(Optional name) { ... } // bad — use overloads or @Nullable instead

Avoid Magic Numbers

Always extract magic numbers into named constants.

script.java

private static final int MAX_RETRIES = 3;if (retryCount > MAX_RETRIES) { ... } // goodif (retryCount > 3) { ... }           // bad