福建农林大学计算机与信息学院JAVA语言程序设计课件Chapter7 Multidimensional Arrays.pptVIP

Introduction to Java Programming Chapter 7 Intro to Java Progrmming Chapter 7 Multidimensional Arrays Motivations Thus far, you have used one-dimensional arrays to model linear collections of elements. You can use a two-dimensional array to represent a matrix or a table. Objectives To give examples of representing data using two-dimensional arrays (§7.1). To declare variables for two-dimensional arrays, create arrays, and access array elements in a two-dimensional array using row and column indexes (§7.2). To program common operations for two-dimensional arrays (displaying arrays, summing all elements, finding min and max elements, and random shuffling) (§7.3). To pass two-dimensional arrays to methods (§7.4). To use multidimensional arrays (§7.8). 7.2 Multidimensional Array Basics 7.2.1 Declaring Variables of two-dimensional Arrays and Creating two-dimensional Arrays dataType[][] arrayRefVar; arrayRefVar = new dataType[rows][columns]; 7.2.2 Obtaining the Lengths of two-dimensional Arrays 7.2.3 Ragged Arrays 7.2.1 Declaring Variables of Two-dimensional Arrays and Creating Two-dimensional Arrays int[][] matrix = new int[10][10]; or int matrix[][] = new int[10][10]; matrix[0][0] = 3; for (int i = 0; i matrix.length; i++) for (int j = 0; j matrix[i].length; j++) matrix[i][j] = (int)(Math.random() * 1000); double[][] x; Declaring, Creating, and Initializing Using Shorthand Notations You can also use an array initializer to declare, create and initialize a two-dimensional array. For example, Lengths of Two-dimensional Arrays int[][] x = new int[3][4]; Lengths of Two-dimensional Arrays, cont. int[][] array = { {1, 2, 3}, {4, 5, 6}, {7, 8, 9}, {10, 11, 12} }; Ragged Arrays Each row in a two-dimensional array is itself an array. So, the rows can have different lengths. Such an array is known as a ragged array. For example, int[][] matrix = { {1, 2, 3, 4, 5}, {2, 3, 4, 5}, {3, 4, 5}, {4, 5}, {5} }; Ragged Arrays, cont. Processing Two-D