Java Multidimensional Arrays

4 Key excerpts on "Java Multidimensional Arrays"

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  eBook - PDF

  Java Programming

  • Joyce Farrell(Author)
  • 2018(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  Copyright 2019 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. 435 Using Two-Dimensional and Other Multidimensional Arrays Because a two-dimensional array with equal-length rows is rectangular, a jagged array can also be called a non-rectangular array. You create a jagged array by defining the number of rows for a two-dimensional array, but not defining the number of columns in the rows. For example, suppose that you have four sales representatives, each of whom covers a different number of states as their sales territory. Further suppose that you want an array to store total sales for each state for each sales representative. You would define the array as follows: double[][] sales = new double[4][]; This statement declares an array with four rows, but the rows are not yet created. Then, you can declare the individual rows, based on the number of states covered by each salesperson as follows: sales[0] = new double[12]; sales[1] = new double[18]; sales[2] = new double[9]; sales[3] = new double[11]; Using Other Multidimensional Arrays Besides one- and two-dimensional arrays, Java also supports arrays with three, four, and more dimensions. The general term for arrays with more than one dimension is multidimensional arrays. For example, if you own an apartment building with a number of floors and different numbers of bedrooms available in apartments on each floor, you can use a two- dimensional array to store the rental fees. If you own several apartment buildings, you might want to employ a third dimension to store the building number.

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  eBook - PDF

  C# Programming

  From Problem Analysis to Program Design

  • Barbara Doyle, , , (Authors)
  • 2015(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  Two-Dimensional Arrays Two-dimensional and other multidimensional arrays follow the same guidelines you learned about with one-dimensional arrays. One-dimensional arrays are useful for stor-ing lists of data. Because the data is stored in contiguous memory locations, elements are referenced by an index representing the location relative to the beginning element of the array. Two-dimensional arrays, the most common multidimensional arrays, are used to store information that we normally represent in table form. Two kinds of two-dimensional arrays can be created using C#. Rectangular is the first type, and this type is supported by most languages. The second type is called a jagged or ragged array. Two-dimensional arrays are referenced much like you reference a matrix or table. Rectangular Array A rectangular two-dimensional array is usually visualized as a table divided into rows and columns. Much like a spreadsheet in which the rows and columns inter-sect, data is stored in individual cells. Figure 8-1 shows a table you might create to store calories consumed for a seven-day period. The table contains three columns and seven rows. Each cell holds one integer value. FIGURE 8-1 Two-dimensional structure © Cengage Learning Copyright 2016 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. Two-Dimensional Arrays | 461 8 A structure can be created in memory to hold these values using a two-dimensional array.

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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)

  We have already discussed 1-D arrays/one-dimensional arrays and their various types and operations. Now, we will learn about two-dimensional arrays. Unlike one-dimensional arrays, 2-D arrays are organized in the form of grids or tables. They are a collection of 1-D arrays. One-dimensional arrays are linearly organized in the memory. A 2-D array consists of two subscripts:

  1. first subscript: which denotes the row
  2. second subscript: which denotes the column

  A 2-D array is represented as shown in the following figure:

  Figure 3.5. Representation of a 2-D array.

  3.8  Declaration of Two-Dimensional Arrays

  As we declared 1-D arrays, similarly we can declare two-dimensional arrays. For declaring two-dimensional arrays, we must know the name of the array, the data type of each element, and the size of each dimension (size of rows and columns).

  Syntax:

  data_type[][] array_name = new int [row_size] [column_size];

  A two-dimensional array is also called an m X n array, as it contains m X n elements where each element in the array can be accessed by i and j, where i<=m and j<=n, and where i, j, m, n are defined as follows:

  i, j = subscripts of array elements, m = number of rows, n = number of columns.

  For example: Let us take an array of 3 X 3 elements. Therefore, the array is declared as:

  int marks [3] [3];

  In the previous diagram the array has three rows and three columns. The first element in the array is denoted by marks [0] [0] . Similarly, the second element will be denoted by marks [0] [1] , and so on. Also, data elements in an array can be stored in the memory in two ways:

  Row Major Order

  In row major order the elements of the first row are stored before the elements of the second, third, and n rows. Here the data elements are stored on a row-by-row basis:

  Column Major Order

  In column major order the elements of the first column are stored before the elements of the second, third, and n columns. Here the data elements are stored on a column-by-column basis:

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  eBook - PDF

  Computer Programming NQF4 Student's Book

  TVET FIRST

  • S Sasti D Sasti(Author)
  • 2020(Publication Date)
  • Troupant

    (Publisher)

  Summary of Module 3 1. Multidimensional data structures generally store data in a tabular form. 2. 2D arrays are similar to a matrix and have rows and columns. We have index numbers for the rows and columns. 3. Database tables are represented as fields and records . 4. Syntax for declaring a 2D array: Dim | Private NameOfTheArray (HighestRowIndexNo, HighestColumnIndexNo) AS DataType 5. In 2D arrays, we have row elements and column elements. Therefore, we need two nested loops for accessing each element in a 2D array. The outside loop represents the row index values and an inner loop represents the column index values. 6. There are two ways to manage groups of objects: l Creating an array of objects . l Creating a collection of objects . 7. Each element in the array is an object/instance of a class. 8. Each array element can access the object’s data members and member methods . 9. Each array element must be an instance of the same class . 10. A collection is a structure where one or more objects can be stored, accessed or operated on. 11. Lists are ordered collections of objects of the same type. 12. ArrayLists are data structures that are a collection of objects of different types. 97 Module 3 Test yourself on Module 3 1. Multiple choice [ ¹ 15 min] 1.1 If the decPrice array is a two-dimensional array, which of the following assigns the highest column subscript to the intHighCol variable? a. intHighCol = decPrice.GetHighestSub(0). b. intHighCol = decPrice.GetHighBound(1). c. intHighCol = decPrice.GetUpperBound(0). d. None of the above. 1.2 Which of the following adds the number 50 to the value stored in the first row, second column of the decPrice array? a. decPrice (0, 1) += 50. b. decPrice (1, 2) = decPrice (1, 2) + 50. c. decPrice (1, 2) += 50. d. Both b and c. 1.3 Which of the following will repeat the loop instructions for each row in a two-dimensional array named intNum? a. For intRow As Integer = 0 To intNum.GetUpperBound(0).

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