Java variable types

Java variable types

• 2.
  Variable Types • Eachvariable in Java has a specific type, which determines the size and layout of the variable's memory. • the range of values that can be stored within that memory. • Variable Declaration: datatype variable = value ; datatype variable = value , variable = value,…;
• 3.
  Variable Types • Example inta, b, c; // Declares three int’s, a, b, and c. int a = 10, b = 10; // Example of initialization byte B = 22; // initializes a byte type variable B. double pi = 3.14159; // declares and assigns a value of PI. char a = 'a'; // the char variable a is initialized with value 'a'
• 4.
  Variable Types • VariableTypes • Local Variable • Instance Variable • Class / Static Variable
• 5.
  Variable Type –Local Variable • It declared inside of methods, constructors, or blocks. • Access modifier cannot be used for local variable. • Local variables are visible only within the methods. • Variable can be accessed when the method is called. Class { method { declare variable } }
• 6.
  Variable Type –Local Variable public class Dog { public void dogAge() { int age = 0; age = age + 7; System.out.println(“Dog age is : “ + age); } public static void main(String args[]) { Dog dog = new Dog(); dog.pupAge(); } }
• 7.
  Variable Type –Instance Variable • It declare inside of a class but outside of methods. • This variable can be access by any methods. • By creating object for a class, we can access this variable from main methods. Class { declare variable method { //can use var } }
• 8.
  Variable Type –Instance Variable public class Dog { int age; public void Dog(int i) { age = i; } public void display() { System.out.println(“Dog age is : “ + age); } public static void main(String args[]) { Dog dog = new Dog(30); dog.display(); } }
• 9.
  Variable Type –Class / Static Variable • Variable declared inside of class but outside of methods with static keyword. • Static variables are stored in the static memory. • Static variables can be accessed by static methods or constructors. Class { declare static variable constructor { //can use var } static method { //can use var } }
• 10.
  Variable Type –Class / Static Variable public class Dog { static int age; public void Dog(int i) { age = i; System.out.println(age); //30 } public static void main(String args[]) { Dog dog = new Dog(30); dog.display(); age= 40; System.out.println(age); //40 } }