Java syntax: Difference between revisions

Revision as of 13:48, 24 August 2025

Revision as of 13:57, 24 August 2025

Line 278:

Classes in the package java.lang are implicitly imported into every program, as long as no explicitly-imported types have the same names. Important ones include:

===={{mono|java.lang.Object}}====

{{code|java.lang.Object}} is Java's [[top type]]. It is implicitly the superclass of all classes that do not declare any parent class (thus all classes in Java inherent from <code>Object</code>. All values can be converted to this type, although for primitive values this involves [[Object type (object-oriented programming)#Autoboxing|autoboxing]].

===={{mono|java.lang.Record}}====

All [[Record (computer science)|records]] implicitly extend {{code|java.lang.Record}}.

===={{mono|java.lang.Enum}}====

All [[enumerated type]]s (enums) in Java implicitly extend {{code|java.lang.Enum}}. Thus, an <code>enum</code>, while treated as a <code>class</code>, cannot extend any other class.

====java.lang.String====

{{code|java.lang.String}} is Java's basic string type. It is [[immutable object|Immutable]]. It does not implement {{code|Iterable<Character>}}, so it cannot be iterated over in a for-each loop, but can be converted to <code>char[]</code>. Some methods treat each [[UTF-16]] code unit as a "character"<code>char</code>, but methods to convert to an <code>int[]</code> that is effectively [[UTF-32]] are also available. <code>String</code> implements <code>CharSequence</code>, so <code>char</code>s in the <code>String</code> can be accessed by the method <code>charAt()</code>.

====java.lang.Throwable====