Arrays in Java | Edureka

Array in Java Types of Arrays Topics For Today’s Discussion JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Topics for Today’s Session DeclaringAccessingUpdatingCreatingWorking with Array Sorting in Arrays Searching in Arrays

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Java Array Array is a static Data Structure Contains collections of homogenous elements All the elements are stored under one variable name It occupies a contiguous memory location

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Types Of Arrays 01Single Dimensional Single Dimensional or 1-D array is a type of linear array in which elements are stored in a continuous row 02Two Dimensional Two Dimensional or 2-D array is a type of matrix in which elements are stored in rows and columns 03Multi Dimensional Multi Dimensional array is a type of nested array

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Working With Arrays – 1D arrayRefVar = new dataType[arraySize]; =myArray new int[5] Declaring and Initializing an One Dimensional Array datatype[] arrayRefVar = new dataType[arraySize]; =int[5] myArray new int[5]

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Working With Arrays – 1D myArray myArray[0] myArray[1] myArray[2] myArray[3] myArray[4] =myArray[0] 10 Declaring and Initializing an One Dimensional Array

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Working With Arrays – 1D myArray myArray[0] myArray[1] myArray[2] myArray[3] myArray[4] =myArray[2] 10 30 =myArray[3] 40 =myArray[4] 50 =myArray[1] 20 Declaring and Initializing an One Dimensional Array

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training myArray myArray[0] myArray[1] myArray[2] myArray[3] myArray[4] 10 30 40 5020 Working With Arrays – 1D Declaring and Initializing an One Dimensional Array

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 10 30 40 5020 Working With Arrays – 1D dataType[] arrayRefVar = new dataType{e1,e2,e3,…,eN}; myArray[0] myArray[1] myArray[2] myArray[3] myArray[4] =int[] myArray new int{10,20,30,40,50} Declaring and Initializing an One Dimensional Array

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training myArray[0] myArray[1] myArray[2] myArray[3] myArray[4] 10 30 40 5020 Working With Arrays – 1D int[] myArray dataType[] arrayRefVar = new dataType{e1,e2,e3,…,eN}; Declaring and Initializing an One Dimensional Array

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Working With Arrays – 1D Accessing a specific array element myArray[0] myArray[1] myArray[2] myArray[3] myArray[4] 10 30 40 50 20 arrayRefVar[index] myArray[4] myArray[1]

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 100 Working With Arrays – 1D Accessing a specific array element myArray[0] myArray[1] myArray[2] myArray[3] myArray[4] 10 30 40 50 20 arrayRefVar[index] myArray[4] myArray[1] Updating a specific array element arrayRefVar[index] = newValue myArray[4] = 100

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training myArray[4] = 100 Working With Arrays – 1D Accessing a specific array element myArray[0] myArray[1] myArray[2] myArray[3] myArray[4] 10 30 50 20 arrayRefVar[index] myArray[4] myArray[1] Updating a specific array element arrayRefVar[index] = newValue 100

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Working With Arrays – 2D Declaring and Initializing an Two Dimensional Array datatype[][] arrayRefVar = new dataType[row][col]; =int[][] myArray new int[2][2] myArray[0][0] myArray[0][1] myArray[1][0] myArray[1][1] =myArray[0][0] 100

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training myArray[0][0] myArray[0][1] myArray[1][0] myArray[1][1] Working With Arrays – 2D Declaring and Initializing an Two Dimensional Array datatype[][] arrayRefVar = new dataType[row][col]; =int[][] myArray new int[2][2] =myArray[0][1] 200 100 =myArray[1][0] 300 =myArray[1][1] 400

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training myArray[0][0] myArray[0][1] myArray[1][0] myArray[1][1] Working With Arrays – 2D Declaring and Initializing an Two Dimensional Array datatype[][] arrayRefVar = new dataType[row][col]; =int[][] myArray new int[2][2] 100 200 300 400

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 564 myArray[0][0] myArray[0][1] myArray[1][0] myArray[1][1] Working With Arrays – 2D arrayRefVar[row][col] 100 200 300 400 Accessing a specific array element myArray[0][1] Updating a specific array element arrayRefVar[row][col] = newValue myArray[0][1] = 564

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training myArray[0][1] = 564 myArray[0][0] myArray[0][1] myArray[1][0] myArray[1][1] Working With Arrays – 2D arrayRefVar[row][col] 100 300 400 Accessing a specific array element myArray[0][1] Updating a specific array element arrayRefVar[row][col] = newValue 564

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Operations With Arrays 1 2 3 6 987 4 5 1 2 1 3 271 5 4 Addition of Matrices a[3][3] b[3][3]

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Operations With Arrays 1 2 3 6 987 4 5 1 2 1 3 271 5 4 2 4 4 9 11158 9 9 a[3][3] b[3][3] c[3][3] int[][] c = new int[rows][columns]; for (int i = 0; i < rows; i++) { for (int j = 0; j < columns; j++) { c[i][j] = a[i][j] + b[i][j]; } }

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 1 2 3 6 987 4 5 1 2 1 3 271 5 4 Division a[3][3] b[3][3] Operations With Arrays Multiplication Subtraction

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Sorting in Array Java offers various sorting algorithms that helps in putting elements of a list in a certain order Bubble Sort Insertion Sort Merge Sort Quick SortSelection Sort Types of Sorting Algorithms

Merge SortQuick SortInsertion SortSelection SortBubble Sort JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 4 1 10 -3 12 4 1 10 -3 12 1 4 10 -3 12 1 4 10 -3 12 1 4 -3 10 12 1 4 -3 10 12 1 -3 4 10 12 1 -3 4 10 12 1 -3 4 10 12 -3 1 4 10 12 -3 1 4 10 12 void bubbleSort(int arr[]) { int n = arr.length; for (int i = 0; i < n-1; i++) for (int j = 0; j < n-i-1; j++) if (arr[j] > arr[j+1]) { // swap temp and arr[i] int temp = arr[j]; arr[j] = arr[j+1]; arr[j+1] = temp; } }

Merge SortQuick SortInsertion SortSelection SortBubble Sort JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 4 1 10 -3 12 4 1 10 -3 12 -3 1 10 4 12 -3 1 10 4 12 -3 1 4 10 12 void selectionSort(int arr[]) { int n = arr.length; // One by one move boundary of unsorted subarray for (int i = 0; i < n-1; i++) { // Find the minimum element in unsorted array int min_idx = i; for (int j = i+1; j < n; j++) if (arr[j] < arr[min_idx]) min_idx = j; // Swap the found minimum element with the first element int temp = arr[min_idx]; arr[min_idx] = arr[i]; arr[i] = temp; } }

Merge SortQuick SortInsertion SortSelection SortBubble Sort JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 4 1 10 -3 12 4 1 10 -3 12 1 4 10 -3 12 1 4 10 -3 12 -3 1 4 10 12 public static int[] insertionSort(int[] input){ int temp; for (int i = 1; i < input.length; i++) { for(int j = i ; j > 0 ; j--){ if(input[j] < input[j-1]){ // Swap with the smallest value temp = input[j]; input[j] = input[j-1]; input[j-1] = temp; } } } return input; } -3 1 4 10 12

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 2 6 7 4 1 -2 8 4 3 2 6 7 4 1 -2 8 4 3 2 7 3 1 -2 8 4 46 2 1 6 7 -2 8 4 43 2 1 -2 4 6 8 7 43 2 1 -2 4 4 8 7 63 private void quickSort(int low, int high) { int i = low; int j = high; // pivot is middle index int pivot = input[low + (high - low) / 2]; // Divide into two arrays while (i <= j) { while (input[i] < pivot) { i++; } while (input[j] > pivot) { j--; } if (i <= j) { swap(i, j); // move index to next position on both sides i++; j--; } } Merge SortQuick SortInsertion SortSelection SortBubble Sort

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 2 6 7 4 1 -2 8 4 3 2 6 7 4 1 -2 8 4 3 2 7 3 1 -2 8 4 46 2 1 6 7 -2 8 4 43 2 1 -2 4 6 8 7 43 2 1 -2 4 4 8 7 63 swap(i, j); // move index to next position on both sides i++; j--; } } Merge SortQuick SortInsertion SortSelection SortBubble Sort // calls quickSort() method recursively if (low < j) { quickSort(low, j); } if (i < high) { quickSort(i, high); } } private void swap(int i, int j) { int temp = input[i]; input[i] = input[j]; input[j] = temp; } }

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Merge SortQuick SortInsertion SortSelection SortBubble Sort 4 1 10 -3 12 4 1 10 -3 12 4 1 10 -3 12 4 1 10 -3 12 1 4 10 -3 12 1 4 10 -3 12 -3 1 4 10 12 // Merges two subarrays of arr[] // First subarray is arr[l..m] // Second subarray is arr[m+1..r] void mergeSort(int arr[], int l, int m, int r) { // Find sizes of two subarrays to be merged int n1 = m - l + 1; int n2 = r - m; /* Create temp arrays */ int L[] = new int [n1]; int R[] = new int [n2]; /*Copy data to temp arrays*/ for (int i=0; i<n1; ++i) L[i] = arr[l + i]; for (int j=0; j<n2; ++j) R[j] = arr[m + 1+ j];

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 4 1 10 -3 12 4 1 10 -3 12 4 1 10 -3 12 1 4 10 -3 12 1 4 10 -3 12 -3 1 4 10 12 /* Merge the temp arrays */ // Initial indexes of first and second subarrays int i = 0, j = 0; // Initial index of merged subarry array int k = l; while (i < n1 && j < n2) { if (L[i] <= R[j]) { arr[k] = L[i]; i++; } else { arr[k] = R[j]; j++; } k++; } for (int i=0; i<n1; ++i) L[i] = arr[l + i]; for (int j=0; j<n2; ++j) R[j] = arr[m + 1+ j]; 4 1 10 -3 12 Merge SortQuick SortInsertion SortSelection SortBubble Sort

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 4 1 10 -3 12 4 1 10 -3 12 4 1 10 -3 12 4 1 10 -3 12 1 4 10 -3 12 1 4 10 -3 12 -3 1 4 10 12 /* Copy remaining elements of L[] if any */ while (i < n1) { arr[k] = L[i]; i++; k++; } /* Copy remaining elements of R[] if any */ while (j < n2) { arr[k] = R[j]; j++; k++; } } k++; } Merge SortQuick SortInsertion SortSelection SortBubble Sort

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 4 1 10 -3 12 4 1 10 -3 12 4 1 10 -3 12 4 1 10 -3 12 1 4 10 -3 12 1 4 10 -3 12 -3 1 4 10 12 k++; } } Merge SortQuick SortInsertion SortSelection SortBubble Sort // Main function that sorts arr[l..r] using // merge() void sort(int arr[], int l, int r) { if (l < r) { // Find the middle point int m = (l+r)/2; // Sort first and second halves sort(arr, l, m); sort(arr , m+1, r); // Merge the sorted halves merge(arr, l, m, r); } }

JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training Sorting in Array Java offers various sorting algorithms that helps in putting elements of a list in a certain order Types of Searching Algorithms Binary SearchLinear Search

Binary SearchLinear Search JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 4 1 10 -3 12 static int search(int arr[], int n, int x) { for (int i = 0; i < n; i++) { // Return the index of the element if the element // is found if (arr[i] == x) return i; } // return -1 if the element is not found return -1; }

Binary SearchLinear Search JAVA CERTIFICATION TRAINING www.edureka.co/java-j2ee-soa-training 2 6 7 9 15 26 50 79 83 2 6 7 9 15 26 50 79 83 15 26 50 79 83 int binarySearch(int arr[], int l, int r, int x) { if (r>=l) { int mid = l + (r - l)/2; // If the element is present at the // middle itself if (arr[mid] == x) return mid; // If element is smaller than mid, then // it can only be present in left subarray if (arr[mid] > x) return binarySearch(arr, l, mid-1, x); // Else the element can only be present // in right subarray return binarySearch(arr, mid+1, r, x); }

Arrays in Java | Edureka

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