Java Data Type Casting Type Conversion

Java Data Type Casting Type Conversion


Java Data Type Casting Type Conversion

Summary: By the end of this tutorial "Java Data Type Casting Type Conversion", you will be comfortable with converting one data type to another either implicitly or explicitly.

Java supports two types of castings – primitive data type casting and reference type casting. Reference type casting is nothing but assigning one Java object to another object. It comes with very strict rules and is explained clearly in Object Casting. Now let us go for data type casting.

Java data type casting comes with 3 flavors.

  1. Implicit casting
  2. Explicit casting
  3. Boolean casting.

1. Implicit casting (widening conversion)

A data type of lower size (occupying less memory) is assigned to a data type of higher size. This is done implicitly by the JVM. The lower size is widened to higher size. This is also named as automatic type conversion.

Examples:

In the above code 4 bytes integer value is assigned to 8 bytes double value.

2. Explicit casting (narrowing conversion)

A data type of higher size (occupying more memory) cannot be assigned to a data type of lower size. This is not done implicitly by the JVM and requires explicit casting; a casting operation to be performed by the programmer. The higher size is narrowed to lower size.

In the above code, 8 bytes double value is narrowed to 4 bytes int value. It raises error. Let us explicitly type cast it.

The double x is explicitly converted to int y. The thumb rule is, on both sides, the same data type should exist.

3. Boolean casting

A boolean value cannot be assigned to any other data type. Except boolean, all the remaining 7 data types can be assigned to one another either implicitly or explicitly; but boolean cannot. We say, boolean is incompatible for conversion. Maximum we can assign a boolean value to another boolean.

Following raises error.

byte –> short –> int –> long –> float –> double

In the above statement, left to right can be assigned implicitly and right to left requires explicit casting. That is, byte can be assigned to short implicitly but short to byte requires explicit casting.

Following char operations are possible

Pass your comments for the betterment of this tutorial "Java Data Type Casting Type Conversion".

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Your one stop destination for all data type conversions

byte TO short int long float double char boolean
short TO byte int long float double char boolean
int TO byte short long float double char boolean
float TO byte short int long double char boolean
double TO byte short int long float char boolean
char TO byte short int long float double boolean
boolean TO byte short int long float double char

String and data type conversions

String TO byte short int long float double char boolean
byte short int long float double char boolean TO String

25 thoughts on “Java Data Type Casting Type Conversion

  1. jayant isswani

    Sir can you please tell what is wrong with this fragment of code ?
    byte b=10;
    byte c=20;
    byte d=b+c; – This statement generates an error stating “possible loss of precision”

  2. Amar

    Suppose if i give inputs from keyboard to a variable and if i declare that variable as int and the given input is in double type(eg.2.3) and i have declared int for that variable so i get exceptions pls guide me
    Program
    import java.util.Scanner;
    class Program
    {
    public static void main(String[] args)
    {

    Scanner s1=new Scanner(System.in);
    int x1=s1.nextInt();// if i give here input as 12.3 i get error
    System.out.println(“x1 value : “+x1);

    }
    }

  3. akash agrawal

    Sir as per your notes from small data type to large data type it is implicit conversion and for high data type to small data type we reqiure explicit conversion so how a long which is a data type converted automatically into float by jvm automatically as per your type promotion chart.

    Pls reply important

    1. S. Nageswara Rao, Corporate Trainer Post author

      See my notes given:

      byte –> short –> int –> long –> float –> double

      The left-side value can be assigned to any right-side value and is done implicitly. The reverse like float to short requires explicit casting.

      I put another question to you. double and long each take 8 bytes memory. Which can be assigned to what? long can be assigned to double but double cannot be assigned to long. Why? It is due to floating-point acceptance.

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