Convert int to double in java

In this article, you will learn three easy ways to convert int to double in java

  1. Implicit casting,
  2. Explicit casting, and
  3. Using the Double class.

Let’s get started and explore each method with practical examples.

1. Implicit Casting

Implicit casting means Java automatically converts an int value to a double when required.
This is because double data type has a wider range and greater memory size than the int data type.
This means that Java can automatically convert an int value to a double when necessary, without requiring any explicit casting on your part.

For example, let’s say you have an int variable with a value of 10, and you want to assign it to a double variable. You can do this simply by assigning the int value to the double variable, like this

java int intValue = 10; 
double doubleValue = intValue;

In this case, Java will automatically convert the int value to a double, so you don’t need to worry about explicit casting.
This is because the double data type can handle the entire range of values that can be represented by an int, so there’s no risk of data loss during the conversion.

2. Explicit Casting

There are situations where you want to explicitly control conversion of int to double in java.

In explicit casting, you’re telling Java to treat an int value as a double value.
This is useful when you want to ensure that a specific operation is performed as a double operation, rather than an int operation.
To do this, you use a cast operator, which is a pair of parentheses containing the target data type.

Here’s an example of explicit casting

java int myInt = 10; 
double myDouble = (double) myInt;

In this example, you’re explicitly telling Java to treat the int value as a double value.
The (double) cast operator is used to perform this conversion.

Note that explicit casting can also be used to convert a larger data type to a smaller one, but this can lead to loss of data if the value is too large for the smaller data type.
In the case of converting an int to a double, there’s no risk of data loss, since a double can represent all possible int values.

Explicit casting gives you more control over your code and can be useful in situations where you need to ensure that a specific operation is performed as a double operation.
However, it’s generally recommended to use implicit casting whenever possible, as it’s more concise and easier to read.

3. Using valueOf() method of Double Class

This method is particularly useful when you need to ensure that the conversion is done correctly and without any loss of precision.
The valueOf() method of java.lang.Double takes an int value as an argument and returns a Double object representing the same value.

Here’s an example of how you can use the valueOf() method to convert an int to a double

int intValue = 10; 
Double doubleValue = Double.valueOf(intValue); 
System.out.println(doubleValue); // Output: 10.0

In this example, the int value 10 is passed to the valueOf() method, which returns a Double object representing the same value.
The resulting double value is then printed to the console.

Note that the valueOf() method returns a Double object, not a primitive double value.
If you need to work with a primitive double value, you can use the doubleValue() method to extract the primitive value from the Double object

double primitiveDoubleValue = doubleValue.doubleValue(); 
System.out.println(primitiveDoubleValue); // Output: 10.0

By using the valueOf() method, you can ensure that your int-to-double conversions are done correctly and with precision, giving you more control over your code.

Common Issues

Most programmers, regardless of their experience level, encounter issues when working with int to double conversion in java.
Listed below are some common problems you may face along with the solutions to overcome them.

IssueSolution
Error: Loss of precision when converting int to doubleThis error occurs when you try to assign a large int value to a double variable.
To avoid this, ensure that the int value is within the range of the double data type as below

int largeInt = 2147483647;
double doubleValue = largeInt;
Error: Cannot convert int to double implicitlyThis error occurs when you try to assign an int value to a double variable without explicit casting. To fix this, use explicit casting as shown below

int intValue = 10;
double doubleValue = (double) intValue;
Error: Null pointer exception when using Double.valueOf()This error occurs when you pass a null value to the Double.valueOf() method.
To avoid this, ensure that the int value is not null before calling the method. For example:

int intValue = 10;
if (intValue!= null) {
  double doubleValue = Double.valueOf(intValue);
}

Conclusion

In this article, we learned that Java automatically converts int values to double when assigned, and three ways to achieve this conversion:
implicit casting,
explicit casting, and
using the valueOf() method of the Double class.

Hope the article was useful.