Singlton Class and its Use in Java 

• Ensure that only one instance of a class is created
• Provide a global point of access to the object
• Allow multiple instances in the future without affecting a singleton class's clients

public class ClassicSingleton {
   private static ClassicSingleton instance = null;
   protected ClassicSingleton() {
      // Exists only to defeat instantiation.
   }
   public static ClassicSingleton getInstance() {
      if(instance == null) {
         instance = new ClassicSingleton();
      }
      return instance;
   }
}

In JDK which is written using singleton pattern, here are few of them:

• Java.lang.Runtime with getRuntime() method
• Java.awt.Toolkit with getDefaultToolkit()
• Java.awt.Desktop with  getDesktop()

What will be the result of the following code Snippet

String a=null;
if (a!=null & a.length()>10) {
System.out.println("Success");
}
else {
System.out.println("Failure");
}

Ashish_Deovanshi: when and who is responsible for initialize the sta...

Ashish_Deovanshi: when and who is responsible for initialize the sta...: when and who is responsible for initialize the static variables in java ?

What is the difference between "abstract Class" and "interface" in java ? 

Main Difference between abstract class and interface are ....
Abstract Class is used for Base Class implementation for all the Class whereas interface is used for property of base Class.
Example : Animal, Bird, tiger, fish. All are Animal as abstract class & having properties eat same for all but fly, run and swim is different properties. so we can put eat as abstract method in abstract class and fly, run & swim used as interface.

The difference between abstract class & interface are as under
1) An abstract class can provide complete code whereas interface cannot provide any code at all
2) In abstract class, a class may extend only one abstract class whereas a class may implement several interfaces.
3) An abstract class can have non abstract methods. whereas all methods of an interface are abstract.
4) An abstract class can have instance variables. whereas interface cannot have instance variables
5) An abstract class can contain constructors. Whereas interface cannot contain constructors.
6) Abstract class are fast. Whereas interface are slow .

 

 

when and who is responsible for initialize the static variables in java ?

To know how to install and configure android sdk. please let me know your interest i will explain.

What is checked & Unchecked Exception in java ?