Java Single Dimensional Arrays

8 Key excerpts on "Java Single Dimensional Arrays"

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  eBook - PDF

  Programming with C++

  • Kyla McMullen, Elizabeth Matthews, June Jamrich Parsons, , Kyla McMullen, Kyla McMullen, Elizabeth Matthews, June Jamrich Parsons(Authors)
  • 2021(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  Programmers typically work with one-dimensional and two-dimensional arrays. • A one-dimensional array is linear. The first row of the magic rectangle with its five elements is a one-dimensional array. • A two-dimensional array has rows and columns that form a matrix. The entire magic rectangle is a two-dimensional array. Copyright 2022 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Module 8 ArrAys 127 Array Characteristics (8.1.3, 8.1.4, 8.1.5, 8.1.6) Arrays are homogeneous, ordered, and finite. Homogeneous. Arrays can be filled with character, Boolean, integer, floating-point, or string data. Remem- ber, however, that all the elements of an array have to be the same data type, a characteristic referred to as homogeneous. An array can be filled with integer data, but you cannot have an array containing some integers and some strings. Ordered. Arrays are stored in consecutive memory addresses and each element is identified by a sequential array index enclosed in square brackets. Array indexes are sometimes referred to as subscripts. The first element in an array has an index of [0]. The remaining array elements in a one-dimensional array are indexed in sequence as shown in Figure 8-2. Figure 8-2 Memory allocation for a one-dimensional array 6 7 0×E2452440 0×E2452444 element [0] 8 9 10 0×E2452448 0×E245244C 0×E2452450 element [1] element [2] element [3] element [4] Index Memory address Finite. Because an array is stored in a set of consecutive memory locations, an array cannot have an infinite number of elements.

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  eBook - PDF

  Java Programming Fundamentals

  Problem Solving Through Object Oriented Analysis and Design

  • Premchand S. Nair(Author)
  • 2008(Publication Date)
  • CRC Press

    (Publisher)

  An array is a named collection of contiguous storage locations that can store data items of the same type. 2. Each element of an array is referred to by the array name along with its position or index. Simple Data Structures ■ 589 3. In the case of primitive data types, the array locations are initialized with default values. Thus, integral arrays are initialized by 0 , floating point arrays by 0.0 , and boolean arrays by false . 4. In the case of object references, the array locations are initialized by null . 5. In the case object references, the array locations need to be instantiated. 6. The length of an array is defined as the number of locations and this value is available in an attribute length . 7. During program execution if an array index becomes out of bounds, Java throws an Array IndexOutOfBoundException exception. 8. The assignment operator = and relational operators == and ! = can be used in the context of an array. 9. The assignment operator copies the reference of one array to the other. This form of copying is known as shallow copying. 10. To make a copy of an array object, memory has to be allocated. Further, an element-by-element copying using a repetition structure is required. This form of copying is known as deep copying. 11. The relational operators compare array references only. 12. A two-dimensional array is an array of one-dimensional arrays. 13. A three-dimensional array is an array of two-dimensional arrays or an array of array of arrays. 14. Insertion and deletion of an element in an arbitrary location of an array is not effi cient. 15. In the case of a Vector , there is a default size of 10. 16. A Vector is thread-safe, whereas ArrayList is not. 17. Corresponding to each primitive data type, there is a wrapper class. 18. The wrapper class for int is Integer . 19. The wrapper class for char is Character . EXERCISES 1. Mark the following statements as true or false: a.

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  Data Structures and Program Design Using Java

  A Self-Teaching Introduction

  • D. Malhotra, N. Malhotra(Authors)
  • 2020(Publication Date)
  • Mercury Learning and Information

    (Publisher)

  3

  ARRAYS

  3.1  Introduction

  In the previous chapter we studied the basics of programming in data structures and Java in which we aimed to design good programs, where a good program refers to a program which runs correctly and efficiently by occupying less space in the memory, and also takes less time to run and execute. Undoubtedly, a program is said to be efficient when it executes with less memory space and also in minimal time. In this chapter, we will learn about the concept of arrays. An array is a user-defined data type that stores related information together. Arrays are discussed in detail in the following sections.

  3.2  Definition of an Array

  An array is a collection of homogeneous (similar) types of data elements in contiguous memory. An array is a linear data structure, because all elements of the array are stored in linear order. Let us take an example in which we have ten students in a class, and we have been asked to store the marks of all ten students; then we need a data structure known as an array.

  Figure 3.1. Representation of an array of ten elements.

  In the previous example, the data elements are stored in the successive memory locations and are identified by an index number (also known as the subscript), that is, Ai or A[i]. A subscript is an ordinal number which is used to identify an element of the array. The elements of an array have the same data type, and each element in an array can be accessed using the same name.

   

  Frequently Asked Questions

  1. What is an array? How can we identify an element in the array?

  Ans: An array is a collection of homogeneous (similar) types of data elements in contiguous memory. An element in an array can be identified by its index number, which is also known as a subscript.

  3.3  Array Declaration

  We know that all variables must be declared before they are used in the program. Therefore, the same concept also holds with array variables. An array must be declared before it is used. During the declaration of an array, the size of the array has to be specified. Declaring an array involves the following specifications:

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  eBook - PDF

  An Introduction to Programming with C++

  • Diane Zak(Author)
  • 2015(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 413 Key Terms Chapter Summary • An array is a group of variables that have the same name and data type and are related in some way. The most commonly used arrays in programs are one-dimensional arrays and two-dimensional arrays. • Programmers use arrays to temporarily store related data in the internal memory of the computer. By doing so, a programmer can increase the efficiency of a program because data can be both stored in and retrieved from internal memory much faster than it can be written to and read from a file on a disk. In addition, after the data is entered into an array, the program can use the data as many times as it is needed. • You must declare an array before you can use it. After declaring an array, you can use an assignment statement or the extraction operator to enter data into the array. • Each of the array elements in a one-dimensional array is assigned a unique number, called a subscript. The first element is assigned a subscript of 0. The second element is assigned a subscript of 1, and so on. Because the first array subscript is 0, the last subscript in a one-dimensional array is always one number less than the number of elements. • You refer to each element in a one-dimensional array by the array’s name and the element’s subscript, which is specified in square brackets immediately following the name. • When searching for either the highest or the lowest element in an array, it is a common practice to assign the first array element’s value to the variable that will be used to keep track of the highest or lowest value. • Parallel arrays are two or more arrays whose elements are related by their corresponding subscript (or position) in the arrays. • You can use the bubble sort algorithm to sort a small amount of data stored in an array.

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  eBook - PDF

  Elementary Synchronous Programming

  in C++ and Java via algorithms

  • Ali S. Janfada(Author)
  • 2019(Publication Date)
  • De Gruyter Oldenbourg

    (Publisher)

  https://doi.org/10.1515/9783110616484-008 8 One-dimensional arrays 8.1 vectors In previous chapters, we addressed independent and non-homonymous variables in algorithm writing and programming. Now, we start working with variables named arrays which include one or more indices. These variables have the same name but different indices. In the process of solving certain problems, we have to deal with a large number of variables having similar behaviours in the program. In these situa-tions, defining all the variables independently consumes the time of the algorithm, increases its size and thus makes it useless. Therefore, we use arrays which have ho-monymous variables and different indices in order to overcome this problem. An im-portant advantage of using arrays is in object-oriented programming: arrays, as the predefined objects, pass by the reference. In the present chapter, we concentrate on one-dimensional arrays and remove the phrase “one-dimensional”. This type of array is occasionally regarded as a vector or a list. For example, an array of eight entries is illustrated in the following diagram. u u u u u u u u u[1] u[2] u[3] u[4] u[5] u[6] u[7] u[8] As shown, eight different variables exists in this diagram all having the same name while different indices. In theoretical studies, these variables are written as u 1 , u 2 , …, u 8 . All of the entries of an array should be of the same data type which is then asso-ciated with the array data type. For instance, an array is integer if all of its entries are integers. The declaration of arrays in programming is as follows. declaration of arrays in C++: declaration of arrays in Java: data type array name [ array length ] ; data type ˽ array name []=new ˽ data type [ array length ]; For example, the statement in C++: in Java: int u[8]; int u[]=new int[8]; declares the variable u as a one-dimensional integer array with a length of 9. As re-gards the entry u n in programs, we write u[n] .

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  eBook - PDF

  Introduction to Computational Modeling Using C and Open-Source Tools

  • Jose M. Garrido(Author)
  • 2013(Publication Date)
  • Chapman and Hall/CRC

    (Publisher)

  Chapter 8 Arrays 8.1 Introduction An array stores multiple values of data with a single name and most program-ming languages include facilities that support arrays. The individual values in the array are known as elements . Many programs manipulate arrays and each one can store a large number of values in a single collection. To refer to an individual element of the array, an integer value or variable known as the array index is used after the name of the array. The value of the index repre-sents the relative position of the element in the array. Figure 8.1 shows an array with 13 elements. This array is a data structure with 13 cells, and each cell contains an element value. In the C programming language, the index values start with 0 (zero). FIGURE 8.1: A simple array. To use arrays in a C program the following steps are carried out: 1. Declare the array with appropriate name, size, and type 2. Assign initial values to the array elements 3. Access or manipulate the individual elements of the array In C, an array is basically a static data structure because once the array is de-clared, its size cannot be changed. The size of an array is the number of elements it can store. An array can also be created at execution time using pointers. A simple array has one dimension and is considered a row vector or a column vector. To manipulate the elements of a one-dimensional array, a single index is re-quired. A vector is a single-dimension array and by default it is a row vector. A matrix is a two-dimensional array and the typical form of a matrix is an array with data items organized into rows and columns. In this array, two indexes are used: one index to indicate the column and one index to indicate the row. Figure 8.2 shows 99 100 Introduction to Computational Modeling a matrix with 13 columns and two rows. Because this matrix has only two rows, the index values for the rows are 0 and 1. The index values for the columns are from 0 up to 12.

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  Data Structures and Program Design Using C++

  • D. Malhotra, N. Malhotra(Authors)
  • 2019(Publication Date)
  • Mercury Learning and Information

    (Publisher)

  3

  ARRAYS

  In This Chapter

  • Introduction

  • Definition of an array

  • Array declaration

  • Array initialization

  • Calculating the address of array elements

  • Analyzing an algorithm

  • Abstract data types

  • Declaration of two-dimensional arrays

  • Operations on 2-D arrays

  • Multidimensional arrays/ N-dimensional arrayys

  • Calculating the address of 3-D arrays

  • Arrays and pointers

  • Array of pointers

  • Arrays and their applications

  • Sparse matrices

  • Types of sparse matrices

  • Representation of sparse matrices

  • Summary

  • Exercises

  3.1Introduction

  We have already studied the basics of programming in data structures and C++ in the previous chapter in which we aimed to design good programs, where a good program refers to a program which runs correctly and efficiently by occupying less space in the memory, and also takes less time to run and execute. Undoubtedly, a program is said to be efficient when it executes with less memory space and also in minimal time. In this chapter, we will learn about the concept of arrays. An array is a user-defined data type that stores related information together. Arrays are discussed in detail in the following sections.

  3.2Definition of an Array

  An array is a collection of homogeneous (similar) types of data elements in contiguous memory . An array is a linear data structure because all elements of the array are stored in linear order. Let us take an example in which we have ten students in a class, and we have been asked to store the marks of all ten students; then we need a data structure known as an array.

  FIGURE 3.1 .

  Representation of an array of 10 elements.

  In the previous example, the data elements are stored in the successive memory locations and are identified by an index number (also known as the subscript), that is, Ai or A[i]. A subscript is an ordinal number which is used to identify an element of the array

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  eBook - PDF

  Java All-in-One For Dummies

  • Doug Lowe(Author)
  • 2023(Publication Date)
  • For Dummies

    (Publisher)

  Suppose that you’re working on a program that tracks five years’ worth of sales (2022 through 2026) for a com- pany, with the data broken down for each of four sales territories (North, South, East, and West). You could create 20 separate variables, with names such as sales2022North, sales2022South, sales2022East, and so on. But that gets a little tedious. 514 BOOK 5 Data Structures Alternatively, you could create an array with 20 elements, like this: double[] sales = new sales[20]; But then how would you organize the data in this array so that you know the year and sales region for each element? With a two-dimensional array, you can create an array with an element for each year. Each of those elements in turn is another array with an element for each region. Thinking of a two-dimensional array as a table or spreadsheet is common, like this: Year North South East West 2022 23,853 22,838 36,483 31,352 2023 25,483 22,943 38,274 33,294 2024 24,872 23,049 39,002 36,888 2025 28,492 23,784 42,374 39,573 2026 31,932 23,732 42,943 41,734 Creating a two-dimensional array To declare a two-dimensional array for this sales data, you simply list two sets of empty brackets, like this: double sales[][]; Here sales is a two-dimensional array of type double. To put it another way, sales is an array of double arrays. To create the array, you use the new keyword and provide lengths for each set of brackets, as in this example: sales = new double[5][4]; Here the first dimension specifies that the sales array has five elements. This array represents the rows in the table. The second dimension specifies that each of those elements has an array of type double with four elements. This array rep- resents the columns in the table. Using Arrays CHAPTER 2 Using Arrays 515 A key point to grasp here is that one instance is of the first array, but a separate instance of the second array for each element is in the first array.

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