- String Null Check
- Null is a literal used to assign values to variables
- Strings can be null, empty, or blank
- Empty strings have zero length
- Blank strings contain whitespace characters
- Null strings are created by assigning null keyword
- String null checking uses == operator
- isEmpty() method checks string emptiness but not null
- equals() method compares string content, not null
- != null checks object references for null
- Apache Commons Lang provides null-safe string methods
- Java 11 introduced isBlank() method for string checks
- Date and DateTime
- Date and DateTime can store null values
- Optional<LocalDate> provides safer alternative to null
- Optional can be checked using if-else statements
- Optional assignment uses reference, not value
- Object Null Check
- == operator compares object references
- Objects.isNull() method checks for null references
- Objects.nonNull() checks for non-null references
- Objects.requireNonNull() throws NullPointerException