What is narrowing in java? Explain.

Java 8Object Oriented ProgrammingProgramming

Java provides various datatypes to store various data values. It provides 7 primitive datatypes (stores single values) as listed below −

  • boolean − Stores 1-bit value representing true or, false.
  • byte − Stores twos compliment integer up to 8 bits.
  • char − Stores a Unicode character value up to 16 bits.
  • short − Stores an integer value upto 16 bits.
  • int − Stores an integer value upto 32 bits.
  • long − Stores an integer value upto 64 bits.
  • float − Stores a floating point value upto 32bits.
  • double − Stores a floating point value up to 64 bits.

Converting one primitive data type into another is known as type conversion. There are two types of type conversions −

  • Widening − Converting a lower datatype to a higher datatype is known as widening.
  • Narrowing − Converting a higher datatype to a lower datatype is known as narrowing.

Whenever you assign a lower datatype to higher the Java compiler converts it implicitly and assigns to the specified variable.

Example

 Live Demo

public class CastingExample {
   public static void main(String args[]){
      char ch = 'C';
      int i = ch;
      System.out.println("Integer value of the given character: "+i);
      float f = 10021.224f;
      double d = f;
      System.out.println("double value: "+d);
   }
}

Output

Integer value of the given character: 67
double value: 10021.2236328125

But, when you try to assign a higher datatype to lower, at the time of compilation you will get an error saying “incompatible types: possible lossy conversion”

In the following example we are trying to assign an integer value to a character value −

Example

public class CastingExample {
   public static void main(String args[]){
      int i = 67;
      char ch = i;
      System.out.println("Character value of the given integer: "+ch);
   }
}

Compile time error

On compiling, the above program generates the following error.

CastingExample.java:4: error: incompatible types: possible lossy conversion from int to char
char ch = i;
^
1 error

In the following example we are trying to assign a double value to a float variable.

Example

public class CastingExample {
   public static void main(String args[]){
      double d = 10021.224d;
      float f = d;
      System.out.println("double value: "+f);
   }
}

Compile time error

On compiling, the above program generates the following error.

CastingExample.java:22: error: incompatible types: possible lossy conversion from double to float
float f = d;
^
1 error

Explicit conversion

Therefore, to assign a higher datatype to lower, you need to convert it using the cast operator explicitly as −

float f = (float)d;

Let us rewrite the Example2 and Exampe3 by converting explicitly.

In the following example we are trying to assign an integer value to a character value by converting it explicitly using the cast operator −

Example

 Live Demo

public class CastingExample {
   public static void main(String args[]){
      int i = 67;
      char ch = (char)i;
      System.out.println("Character value of the given integer: "+ch);
   }
}

Output

Character value of the given integer: C

In the following example we are trying to assign a double value to a float variable by converting it explicitly using the cast operator.

Example

 Live Demo

public class CastingExample {
   public static void main(String args[]){
      double d = 10021.224d;
      float f = (float)d;
      System.out.println("double value: "+f);
   }
}

Output

double value: 10021.224
raja
Updated on 30-Jul-2019 22:30:26

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