Found 9326 Articles for Object Oriented Programming

AssociationAssociation refers to the relationship between multiple objects. It refers to how objects are related to each other and how they are using each other's functionality. Composition and aggregation are two types of association.CompositionThe composition is the strong type of association. An association is said to composition if an Object owns another object and another object cannot exist without the owner object. Consider the case of Human having a heart. Here Human object contains the heart and heart cannot exist without Human.AggregationAggregation is a weak association. An association is said to be aggregation if both Objects can exist independently. For ... Read More

With Java 8, Arrays class has a stream() methods to generate a Stream using the passed array as its source.DescriptionThe java.util.Arrays.stream() method returns a sequential Stream with the specified array as its source. −Arrays.stream(array)DeclarationFollowing is the declaration for java.util.Arrays.stream() methodpublic static Stream stream(T[] array)Type ParameterT − This is the type of the array elements.Parameterarray − This is the source array to be used.Return ValueThis method returns a stream for the array.ExampleThe following example shows the usage of java.util.Arrays.stream() method.Live Demoimport java.util.Arrays; public class Tester {    public static void main(String args[]) {       int data[] = { 1, ... Read More

Here is the syntax for declaring an array variable −SyntaxdataType[] arrayRefVar;   // preferred way. or dataType arrayRefVar[];  // works but not preferred way.Note − The style dataType[] arrayRefVar is preferred. The style dataType arrayRefVar[] comes from the C/C++ language and was adopted in Java to accommodate C/C++ programmers.ExampleThe following code snippets are examples of this syntax −double[] myList;   // preferred way. or double myList[];   // works but not preferred way.Creating ArraysYou can create an array by using the new operator with the following syntax −SyntaxarrayRefVar = new dataType[arraySize];The above statement does two things −It creates an array ... Read More

Array in Java can be copied to another array using the following ways.Using variable assignment. This method has side effects as changes to the element of an array reflects on both the places. To prevent this side effect following are the better ways to copy the array elements.Create a new array of the same length and copy each element.Use the clone method of the array. Clone methods create a new array of the same size.Use System.arraycopy() method.  The arraycopy() can be used to copy a subset of an array.ExampleCreate a java class named Tester.Tester.javaLive Demopublic class Tester {    public ... Read More

'+' operator in java can be used to add numbers and concatenate strings. Following rules should be considered.Only numbers as operands then result will be a number.Only strings as operands then result will be a concatenated string.If both numbers and strings as operands, then numbers coming before string will be treated as numbers.If both numbers and strings as operands, then numbers coming after string will be treated as a string.Above rule can be overridden using brackets().ExampleCreate a java class named Tester.Tester.javaLive Demopublic class Tester {    public static void main(String args[]) {             //Scenario 1: ... Read More

The Java.io.StringWriter class is a character stream that collects its output in a string buffer, which can then be used to construct a string. Closing a StringWriter has no effect.The Java.io.PrintWriter class prints formatted representations of objects to a text-output stream.Using these two classes you can convert a Stack Trace to a String.ExampleLive Demoimport java.io.PrintWriter; import java.io.StringWriter; public class StackTraceToString {    public static void main(String args[]) {       try {          int a[] = new int[2];          System.out.println("Access element three :" + a[3]);       } catch (ArrayIndexOutOfBoundsException e) ... Read More

ExampleYou can check if a given string is Numeric as shown in the following program.Live Demoimport java.util.Scanner; public class StringNumeric {    public static void main(String[] args) {       Scanner sc = new Scanner(System.in);       System.out.println("Enter a string ::");       String str = sc.next();       boolean number = str.matches("-?\d+(\.\d+)?");       if(number) {          System.out.println("Given string is a number");       } else {          System.out.println("Given string is not a number");       }    } }OutputEnter a string :: 4245 Given string is a number

The java.io.ByteArrayOutputStream.toString() method converts the stream's contents using the platform's default character set. The malformed-input and unmappable-character sequences are replaced by the default replacement string for the platform's default character set.Example Live Demoimport java.io.ByteArrayOutputStream; import java.io.IOException; public class ByteArrayOutputStreamDemo {    public static void main(String[] args) throws IOException {       String str = "";       byte[] bs = {65, 66, 67, 68, 69};       ByteArrayOutputStream baos = null;       try {          // create new ByteArrayOutputStream          baos = new ByteArrayOutputStream();          // write ... Read More

You can compare two Strings in Java using the compareTo() method, equals() method or == operator.The compareTo() method compares two strings. The comparison is based on the Unicode value of each character in the strings. The character sequence represented by this String object is compared lexicographically to the character sequence represented by the argument string.The result is a negative integer if this String object lexicographically precedes the argument string.The result is a positive integer if this String object lexicographically follows the argument string.The result is zero if the strings are equal, compareTo returns 0 exactly when the equals(Object) method would ... Read More

The FileInputStream class contains a method read(), this method accepts a byte array as a parameter and it reads the data of the file input stream to given byte array. Assume the file myData contains the following data −Exampleimport java.io.File; import java.io.FileInputStream; public class FileToByteArray {    public static void main(String args[]) throws Exception{       File file = new File("myData");       FileInputStream fis = new FileInputStream(file);       byte[] bytesArray = new byte[(int)file.length()];       fis.read(bytesArray);       String s = new String(bytesArray);       System.out.println(s);    } }OutputHi how are you welcome to Tutorialspoint