Teachnique
      CourseRoadmaps
      Login

      OverviewHistoryFeaturesJava 8 - New Featuresvs C++Virtual Machine(JVM)JDK vs JRE vs JVMHello World ProgramEnvironment SetupBasic SyntaxVariable TypesData TypesType CastingUnicode SystemBasic OperatorsCommentsStreamsNew Date-Time API

      Loop ControlDecision Makingif-else Statementswitch statementfor loopfor each Loopwhile Loopdo...while Loopbreak Statementcontinue Statement

      OOPs (Object-Oriented Programming) ConceptsObject and ClassesClass AttributesClass MethodsMethodsVariable ScopesConstructorsAccess ModifiersInheritanceAggregationPolymorphismOverridingMethod OverloadingDynamic BindingStatic BindingInstance Initializer BlockAbstractionEncapsulationInterfacesPackagesInner classesStatic ClassesAnonymous ClassesSingleton ClassWrapper ClassesEnum Class

      Number ClassBoolean classCharacter ClassArraysMath Class

      File ClassCreating FilesWrite To FilesReading FileDelete FilesDirectory OperationsFiles and I/O

      ExceptionsTry Catch BlockTry with ResourcesMultiple Catch BlocksNested Try BlockFinally BlockThrows and Throw | Throw an ExceptionException PropagationBuilt-in ExceptionsCustom Exception

      MultithreadingThread Life CycleCreating a ThreadStarting a ThreadJoining ThreadsNaming a Thread with ExamplesScheduling Threads with ExamplesThread PoolsMain ThreadThread PriorityDaemon ThreadThreadGroup ClassJVM Shutdown Hook

      Thread SynchronizationBlock SynchronizationStatic SynchronizationInter Thread CommunicationThread DeadlockInterrupting ThreadThread ControlReentrant Monitor

      NetworkingSocket ProgrammingURL ProcessingURL ClassURLConnection ClassHttpURLConnection ClassSocket Class with ExamplesGenerics

      Collections FrameworkCollection Interface

      List InterfaceArrayList Class

      Queue InterfaceArrayDeque Class

      Map InterfaceSortedMap Interface

      Set InterfaceSortedSet Interface

      Data Structures Enumeration Interface BitSet Class

      How to Use Iterator?How to Use Comparator?How to Use Comparable?

      RecursionRegular ExpressionsSerializationString ClassJava Arrays - Class

      Feedback

      Submit request if you have any questions.

      Course
      Data Types

      Java Tutorial

      This Java tutorial is tailored for newcomers, offering a journey from basic principles to complex Java programming techniques. Completing this tutorial equips you with a solid understanding of Java, preparing you for advanced learning. You'll emerge ready to tackle the challenges of becoming a top-tier software engineer, with the skills to innovate and excel in the vast world of software development.

      Data Types

      Java Data Types

      Java data types are used to define the type of data for the different types of variables, constants, method parameters, returns type, etc. The variables are nothing but reserved memory locations to store some values. This means that when you create a variable you reserve some space in the memory to store some data. The data type tells the compiler about the type of data to be stored and the required memory.
      Based on the data type of a variable, the operating system allocates memory and decides what can be stored in the reserved memory. Therefore, by assigning different data types to variables, you can store integers, decimals, or characters in these variables.

      Types of Data Types in Java

      There are two data types available in Java
      • Primitive Data Types
      • Reference/Object Data Types

      1. Java Primitive Data Types

      Primitive data types are predefined by the language and named by a keyword. There are eight primitive data types supported by Java. Below is the list of the primitive data types:
      • byte
      • short
      • int
      • long
      • float
      • double
      • boolean

      The byte data type

      • Byte data type is an 8-bit signed two's complement integer
      • Minimum value is -128 (-2^7)
      • Maximum value is 127 (inclusive)(2^7 -1)
      • Default value is 0
      • Byte data type is used to save space in large arrays, mainly in place of integers, since a byte is four times smaller than an integer.
      • Example − byte a = 100, byte b = -50

      The short data type

      • Short data type is a 16-bit signed two's complement integer
      • Minimum value is -32,768 (-2^15)
      • Maximum value is 32,767 (inclusive) (2^15 -1)
      • Short data type can also be used to save memory as byte data type. A short is 2 times smaller than an integer
      • Default value is 0.
      • Example − short s = 10000, short r = -20000

      The int data type

      • Int data type is a 32-bit signed two's complement integer.
      • Minimum value is - 2,147,483,648 (-2^31)
      • Maximum value is 2,147,483,647(inclusive) (2^31 -1)
      • Integer is generally used as the default data type for integral values unless there is a concern about memory.
      • The default value is 0
      • Example − int a = 100000, int b = -200000

      The long data type

      • Long data type is a 64-bit signed two's complement integer
      • Minimum value is -9,223,372,036,854,775,808(-2^63)
      • Maximum value is 9,223,372,036,854,775,807 (inclusive)(2^63 -1)
      • This type is used when a wider range than int is needed
      • Default value is 0L
      • Example − long a = 100000L, long b = -200000L

      The float data type

      • Float data type is a single-precision 32-bit IEEE 754 floating point
      • Float is mainly used to save memory in large arrays of floating point numbers
      • Default value is 0.0f
      • Float data type is never used for precise values such as currency
      • Example − float f1 = 234.5f

      The double data type

      • double data type is a double-precision 64-bit IEEE 754 floating point
      • This data type is generally used as the default data type for decimal values, generally the default choice
      • Double data type should never be used for precise values such as currency
      • Default value is 0.0d
      • Example − double d1 = 123.4

      The boolean data type

      • boolean data type represents one bit of information
      • There are only two possible values: true and false
      • This data type is used for simple flags that track true/false conditions
      • Default value is false
      • Example − boolean one = true

      The char data type

      • char data type is a single 16-bit Unicode character
      • Minimum value is '\u0000' (or 0)
      • Maximum value is '\uffff' (or 65,535 inclusive)
      • Char data type is used to store any character
      • Example − char letterA = 'A'

      Example: Demonstrating Different Primitive Data Types

      Following examples shows the usage of variour primitive data types we've discussed above. We've used add operations on numeric data types whereas boolean and char variables are printed as such.
      public class JavaTester {
         public static void main(String args[]) {
      
            byte byteValue1 = 2;
            byte byteValue2 = 4;
            byte byteResult = (byte)(byteValue1 + byteValue2);
      
            System.out.println("Byte: " + byteResult);
      
            short shortValue1 = 2;
            short shortValue2 = 4;
            short shortResult = (short)(shortValue1 + shortValue2);
      
            System.out.println("Short: " + shortResult);
      
            int intValue1 = 2;
            int intValue2 = 4;
            int intResult = intValue1 + intValue2;
      
            System.out.println("Int: " + intResult);
      
            long longValue1 = 2L;
            long longValue2 = 4L;
            long longResult = longValue1 + longValue2;
      
            System.out.println("Long: " + longResult);
      
            float floatValue1 = 2.0f;
            float floatValue2 = 4.0f;
            float floatResult = floatValue1 + floatValue2;
      
            System.out.println("Float: " + floatResult);
      
            double doubleValue1 = 2.0;
            double doubleValue2 = 4.0;
            double doubleResult = doubleValue1 + doubleValue2;
      
            System.out.println("Double: " + doubleResult);
      
            boolean booleanValue = true;
      
            System.out.println("Boolean: " + booleanValue);
      
            char charValue = 'A';
      
            System.out.println("Char: " + charValue);     
         }
      }

      Output

      Byte: 6
      Short: 6
      Int: 6
      Long: 6
      Float: 6.0
      Double: 6.0
      Boolean: true
      Char: A

      2. Java Reference/Object Data Type

      The reference data types are created using defined constructors of the classes. They are used to access objects. These variables are declared to be of a specific type that cannot be changed. For example, Employee, Puppy, etc.
      Class objects and various types of array variables come under reference datatype. The default value of any reference variable is null. A reference variable can be used to refer to any object of the declared type or any compatible type.

      Example

      The following example demonstrates the reference (or, object) data types.
      // Creating an object of 'Animal' class
      Animal animal = new Animal("giraffe");
      
      // Creating an object of 'String' class
      String myString = new String("Hello, World!");