Java arrays of strings. Sorting an array in Java. Two-dimensional Java array
In programming practice, there is a hugethe number of different sets and types of data that the system can manipulate and with which the programmer can organize the information being processed.
Types of data in programming languages
It is an integral part of most languagesprogramming, which describes the size and characteristics of data located in a specific memory cell, which ensures the correct operation of programs during the execution of a prescribed operation.
For example, one of the basic types of dataare integer variables. They can be both signed and vice versa, and the name itself already conveys information about the contents of a cell of this kind.
In addition to integer variables, there areanalogs with floating point, which are used to represent real quantities. Finally, the so-called primitive data types include string and character variables and pointers. All this together is a separate linguistic unit.
Data Structures
A higher level of organization inprogramming is the integration of several units of a primitive data type into a more complex structure. Among the composite types, the so-called Java arrays are considered the most common. You can also select lists, tuples, stacks and queues.
The main difference between arrays is that theyprovide random access to their elements. However, the difficulty lies in the fact that the size must be specified as precisely as possible during the initialization phase of the structure. This defect is eliminated in more complex types of data, for example, in lists. Such systems have the ability to dynamically expand with the addition of new elements, but access to data in them takes more time.
In most modern programming languagesall these structures are present and play an extremely important role in the functioning of both applied programs and in the work of the ecosystem itself. And Java is no exception.
Java programming language. Basic units
Java is a strongly typed languageprogramming, the bytecode of which is executed inside the virtual machine, which allows performing operations and obtaining the same result regardless of the architecture of the computing environment and the operating system.
In the latest release of the Java language, there are eightprimitive types: logical boolean, integer byte, integer, short, long, floating point types, represented by float and double, and character char.
A Java array is a collection of dataone type, located in memory one after another and having their own serial number (index), according to which the programmer or the system can access the individual element stored in the array. The indexing starts from zero (the first element) and is incremented by one for each subsequent one. In this case, the Java-array provides random access to data - user code can access any element of the array, regardless of its location within the structure.
Objects
Do not forget that Java is first and foremostobject-oriented programming language. Therefore, these elements are an integral part of the memory model. A peculiarity of systems of this type is that Java arrays can store objects in the same way as they store primitive data types. The most common object in the language are strings. They are sets of symbols organized in a single and immutable memory cell.
An array of Java strings is an ordered set ofpointers to other parts of the memory, in each of which the desired object is stored. The user then receives the required character set from a remote location in the virtual machine's memory and works with it indirectly.
Two-dimensional arrays (matrices)
Such a phenomenon as a matrix is aA two-dimensional array of Java objects or primitives that organizes them according to the "row-column" principle. This data structure is sometimes described as an "array of arrays." This is due to the fact that each row of elements or column is a usual one-dimensional Java-array, and their totality makes up a matrix.
In the two-dimensional variant, each of the vectorshave its own length, different from the rest. When accessing a single element of an array, two indexes are used to indicate the location of the desired memory location. The first is the line number in which the desired object is located. The second index is the number of the column, or the serial number of the element within the vector. The indexing of elements within two-dimensional structures begins from zero, as in the case of one-dimensional arrays. Therefore, to access the last element of an array of length N, the index [N-1] will be used.
Sorting items
The most common task when working witharrays is exactly sorting. This trivial task at first glance is considerably more complicated when the number of elements within a vector or matrix increases.
There are many differentalgorithms designed to sort elements within a particular structure - a bubble method, a selection sort, a merge or insert method. All methods differ between the speed of the task and the amount of memory needed to store temporary data and results obtained during intermediate operations.
Some algorithms may have differentcoefficient of optimality depending on the set of input data. In Java, the sorting of an array can be performed by means of the standard auxiliary class Arrays, which has a static sort method that sorts elements in ascending order and uses the quick-access method. Nevertheless, this algorithm is unstable, and the execution time may differ even when processing arrays of the same length. This sort is known as the fastest for ordered large random lists. Programmers also have access to all the tools for implementing any other sorting algorithm in accordance with the task parameters and the requirements for the result.
