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Object Oriented Programming Articles
Page 488 of 589
How to convert JSON Array to normal Java Array?
The get method of the JSONArray class returns the element at a particular index. Using this method, you can get the elements of the JSONArray object and populate the array with them.Exampleimport java.util.Arrays; import org.json.JSONArray; public class JsonToArray { public static void main(String args[]) throws Exception { String [] myArray = {"JavaFX", "HBase", "JOGL", "WebGL"}; JSONArray jsArray = new JSONArray(); for (int i = 0; i < myArray.length; i++) { ...
Read MoreHow to perform heapsort on an array in Java?
Following is the algorithm for heapsort (maxheap).Step 1 − Create a new node at the end of the heap.Step 2 − Assign new value to the node.Step 3 − Compare the value of this child node with its parent.Step 4 − If the value of parent is less than a child, then swap them.Step 5 − Repeat step 3 & 4 until Heap property holds.Exampleimport java.util.Arrays; import java.util.Scanner; public class Heapsort { public static void heapSort(int[] myArray, int length) { int temp; int size = length-1; for (int i ...
Read MoreHow to declare Java array with array size dynamically?
To declare array size dynamically read the required integer value from the user using Scanner class and create an array using the given value:Exampleimport java.util.Arrays; import java.util.Scanner; public class PopulatingAnArray { public static void main(String args[]) { System.out.println("Enter the required size of the array :: "); Scanner s = new Scanner(System.in); int size = s.nextInt(); int myArray[] = new int [size]; System.out.println("Enter the elements of the array one by one "); for(int i = 0; i
Read MoreHow to define an array size in java without hardcoding?
To avoid hard coding you can read the size of the array from the user using command line arguments of the reader classes like Scanner. Then using this value create an array:Exampleimport java.util.Arrays; import java.util.Scanner; public class PopulatingAnArray { public static void main(String args[]) { System.out.println("Enter the required size of the array :: "); Scanner s = new Scanner(System.in); int size = s.nextInt(); int myArray[] = new int [size]; System.out.println("Enter the elements of the array one by one "); for(int i=0; i
Read MoreHow to populate an array one value at a time by taking input from user in Java?
To read data from user create a scanner class. Read the size of the array to be created from the user using nextInt() method. Create an array with the specified size. In the loop read the values from the user and store in the array created above.Exampleimport java.util.Arrays; import java.util.Scanner; public class PopulatingAnArray { public static void main(String args[]) { System.out.println("Enter the required size of the array :: "); Scanner s = new Scanner(System.in); int size = s.nextInt(); ...
Read MoreHow to divide an array into half in java?
Using the copyOfRange() method you can copy an array within a range. This method accepts three parameters, an array that you want to copy, start and end indexes of the range.You split an array using this method by copying the array ranging from 0 to length/2 to one array and length/2 to length to other.Exampleimport java.util.Arrays; import java.util.Scanner; public class SplittingAnArray { public static void main(String args[]) { Scanner s =new Scanner(System.in); System.out.println("Enter the required size of the array ::"); int size = s.nextInt(); int [] myArray ...
Read MoreHow to read a 2d array from a file in java?
A 2d array is an array of one dimensional arrays to read the contents of a file to a 2d array –Instantiate Scanner or other relevant class to read data from a file. Create an array to store the contents.To copy contents, you need two loops one nested within the other. the outer loop is to traverse through the array of one dimensional arrays and, the inner loop is to traverse through the elements of a particular one dimensional array.Create an outer loop starting from 0 up to the length of the array. Within this loop read each line trim and ...
Read MoreHow to convert an array of objects to an array of their primitive types in java?
Apache Commons provides a library named org.apache.commons.lang3 and, following is the maven dependency to add the library to your project. org.apache.commons commons-lang3 3.0 This package provides a class named ArrayUtils. Using the toPrimitive() method of this class you can convert An object array to an array of primitive types:Exampleimport java.util.Arrays; import org.apache.commons.lang3.ArrayUtils; public class ArraysToPrimitives { public static void main(String args[]) { Integer[] myArray = {234, 76, 890, 27, 10, 63}; int[] primitiveArray = ArrayUtils.toPrimitive(myArray); System.out.println(Arrays.toString(primitiveArray)); } }Output[234, 76, 890, 27, 10, 63]
Read MoreHow to convert an object to byte array in java?
To convert an object to byte arrayMake the required object serializable by implementing the Serializable interface.Create a ByteArrayOutputStream object.Create an ObjectOutputStream object by passing the ByteArrayOutputStream object created in the previous step.Write the contents of the object to the output stream using the writeObject() method of the ObjectOutputStream class.Flush the contents to the stream using the flush() method.Finally, convert the contents of the ByteArrayOutputStream to a byte array using the toByteArray() method.Exampleimport java.io.ByteArrayOutputStream; import java.io.ObjectOutputStream; import java.io.Serializable; class Sample implements Serializable { public void display() { System.out.println("This is a sample ...
Read MoreWhat is length in Java Arrays?
Length is a filed in java, it gives the total number of the elements in a Java array. The length of an array is defined after the array was created.Integer[] myArray = {23, 93, 56, 92, 39}; System.out.println(myArray.length);
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