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Collection implementations in pre-JDK 1.2 versions of the Java platform included few data structure classes, but did not contain a collections framework. [4] The standard methods for grouping Java objects were via the array, the Vector, and the Hashtable classes, which unfortunately were not easy to extend, and did not implement a standard member interface.
In Java associative arrays are implemented as "maps", which are part of the Java collections framework. Since J2SE 5.0 and the introduction of generics into Java, collections can have a type specified; for example, an associative array that maps strings to strings might be specified as follows:
Primitive wrapper classes are not the same thing as primitive types. Whereas variables, for example, can be declared in Java as data types double, short, int, etc., the primitive wrapper classes create instantiated objects and methods that inherit but hide the primitive data types, not like variables that are assigned the data type values.
Java provides java.util.Date, a mutable reference type with millisecond precision, and (since Java 8) the java.time package (including classes such as LocalDate, LocalTime, and LocalDateTime for date-only, time-only, and date-and-time values), a set of immutable reference types with nanosecond precision. [24]
Generics are a facility of generic programming that were added to the Java programming language in 2004 within version J2SE 5.0. They were designed to extend Java's type system to allow "a type or method to operate on objects of various types while providing compile-time type safety". [1]
Sets can be considered sub-cases of corresponding Maps in which the values are always a particular constant which can be ignored, although the Set API uses corresponding but differently named methods. At the bottom is the java.util.concurrent.ConcurrentNavigableMap, which is a multiple-inheritance. java.util.Collection. java.util.Map. java.util ...
Each method will resolve a different problem, so it's important we're familiar with all of them. some() The some() tests whether at least one element in the array passes the test implemented by ...
Actual implementation happens outside Java code, and such methods have no body. strictfp - Declares strict conformance to IEEE 754 in carrying out floating-point operations. synchronized - Declares that a thread executing this method must acquire monitor. For synchronized methods the monitor is the class instance or java.lang.Class if the ...