java.util.Objects #
| Method | Description |
|---|---|
equals(Object a, Object b) |
Safely compares two objects for equality. |
deepEquals(Object a, Object b) |
Performs a deep comparison of two objects, including arrays. |
hash(Object... values) |
Generates a hash code for multiple objects. |
hashCode(Object o) |
Returns the hash code of an object or 0 if null. |
toString(Object o) |
Returns the toString() of an object or "null". |
toString(Object o, String nullDefault) |
Returns the toString() of an object or a default string. |
requireNonNull(T obj) |
Throws NullPointerException if the object is null. |
requireNonNullElse(T obj, T defaultObj) |
Returns the object if non-null, or a default value. |
isNull(Object obj) |
Checks if an object is null. |
nonNull(Object obj) |
Checks if an object is non-null. |
compare(T a, T b, Comparator<? super T> c) |
Compares two objects using a comparator. |
checkIndex(int index, int length) |
Ensures that the index is within valid bounds. |
Exceptions #
| Exception | Type | Description |
|---|---|---|
NullPointerException |
Unchecked | Attempt to use null as if it were an object. |
ArrayIndexOutOfBoundsException |
Unchecked | Accessing an array with an illegal index. |
IllegalArgumentException |
Unchecked | Method argument is inappropriate or illegal. |
IllegalStateException |
Unchecked | Method called at an inappropriate time. |
IndexOutOfBoundsException |
Unchecked | General index is out of range. |
ArithmeticException |
Unchecked | Arithmetic error (e.g., divide by zero). |
ClassCastException |
Unchecked | Invalid casting of an object. |
NumberFormatException |
Unchecked | Failure to convert string to a number. |
IOException |
Checked | I/O operation failure. |
FileNotFoundException |
Checked | File operation on a file that doesn’t exist. |
InterruptedException |
Checked | Thread is interrupted while it is waiting or sleeping. |
SQLException |
Checked | Database access or SQL error. |
NoSuchElementException |
Unchecked | Attempting to access an element that does not exist. |
UnsupportedOperationException |
Unchecked | Operation is unsupported. |
TimeoutException |
Checked | Operation times out. |
OutOfMemoryError |
Error | JVM runs out of memory (serious issue). |