Found 9326 Articles for Object Oriented Programming

The StringBuffer and StringBuilder classes are used when there is a necessity to make a lot of modifications to Strings of characters.Unlike Strings, objects of type StringBuffer and String builder can be modified over and over again without leaving behind a lot of new unused objects.The StringBuilder class was introduced as of Java 5 and the main difference between the StringBuffer and StringBuilder is that StringBuilder’s methods are not thread safe (not synchronized).It is recommended to use StringBuilder whenever possible because it is faster than StringBuffer. However, if the thread safety is necessary, the best option is StringBuffer objects.Read More

When you store a String asString str1 = "Hello";directly, then JVM creates a String object with the given value in a separate block of memory known as String constant pool.And whenever we try to create another String asString str2 = "Hello";JVM verifies whether any String object with the same value exists in the String constant pool, if so, instead of creating a new object JVM assigns the reference of the existing object to the new variable.And when we store String asString str = new String("Hello");using the new keyword, a new object with the given value is created irrespective of the ... Read More

You can create a String by − Step 1 − Assigning a string value wrapped in " " to a String type variable. String message = "Hello Welcome to Tutorialspoint"; Step 2 − Creating an object of the String class using the new keyword by passing the string value as a parameter of its constructor. String message = new String ("Hello Welcome to Tutorialspoint"); Step 3 − Passing a character array to the String constructor. char arr[] = {'H','e','l','l','o'}; String message = new String(arr);

In Java, immutable objects are those whose data can’t be changed or modified (once modified). String class is immutable i.e. once we create a String object its data cannot be modified.

Java provides the java.util.regex package for pattern matching with regular expressions.

transient: An instance variable is marked transient to indicate the JVM to skip the particular variable when serializing the object containing it.  This modifier is included in the statement that creates the variable, preceding the class or data type of the variable.Examplepublic transient int limit = 55;   // will not persist public int b;   // will persistvolatile: The volatile modifier is used to let the JVM know that a thread accessing the variable must always merge its own private copy of the variable with the master copy in the memory.Accessing a volatile variable synchronizes all the cached copied ... Read More

The volatile modifier is used to let the JVM understand that a thread accessing the variable should always merge its own personal copy of the variable with the original in the memory.Accessing a volatile variable synchronizes all the cached copy of the variables in the main memory. Volatile can only be applied to instance variables, which are of type object or private. A volatile object reference can be null.Examplepublic class MyRunnable implements Runnable {    private volatile boolean active;    public void run() {       active = true;       while (active) {           }    }    public void stop() {       active = false;      } }

An instance variable is marked transient to point the JVM to skip the actual variable once serializing the thing containing it. This modifier is included in the statement that creates the variable, preceding the class or data type of the variable. Example public class Employee implements java.io.Serializable { public String name; public String address; public transient int SSN; public int number; public void mailCheck() { System.out.println("Mailing a check to " + name + " ... Read More

Yes, a local variable can be public, private, protected or default.

The final modifier can be associated with methods, classes and variables. Once declared final − A final class cannot be instantiated. A final method cannot be overridden. A final variable cannot be reassigned. Example Live Demo class TestExample { final int value = 10; public static final int BOXWIDTH = 6; static final String TITLE = "Manager"; public final void changeName() { System.out.println("This is a final method"); } } final class ... Read More