How to Convert Double to Int in Java

Last Updated on August 12, 2024 by Abhishek Sharma

In Java programming, data type conversion is a common task that developers encounter, especially when dealing with numeric data. One frequent scenario is converting a double value to an int. This conversion is often necessary when you need to work with integers, such as for indexing, counting, or situations where decimal precision is not required. However, converting from double to int involves more than just changing the data type; it requires careful consideration to avoid losing significant data due to the truncation of the decimal part. This article will guide you through the different methods to safely and effectively convert a double to an int in Java.

Approaches to Convert double to int in Java

Now, let’s discuss in detail all the approaches to convert double to int in Java:

Approach 1: Using TypeCasting in Java

Type Casting in Java is the simplest way to convert double to int in Java. It involves explicitly converting a data type to another data type using the syntax (datatype) variable. When converting a double to an int using type casting, the decimal part of the double value is truncated, i.e., it is simply removed.

Syntax of TypeCasting in Java

double data = 52.6345
int value = (int)data;

Now, let’s look at an example that converts double to int in Java using TypeCasting.

Code Implementation:

class PrepBytes {
    public static void main(String args[])
    {
        double data = 52.6345;
        System.out.println("Double - " + data);
        
        int value = (int)data;

        System.out.println("Integer - " + value);
    }
}

Output:

Double - 52.6345
Integer - 52

Explanation: In the above Java example, we declare a class named "PrepBytes" with a "main" method. The "main" method starts by creating a double variable "data" and assigning it the value 52.6345. Next, our Java program converts the double variable "data" to an integer variable "value". After that, we print the value of "value" to the console.

Approach 2: Using Math.round() Method

When we use the Math.round() method to convert a double to int in Java, the decimal part of the double value is rounded to the nearest long value by adding 0.5 and trimming the decimal points. Typecasting can then be used to transform the long value to an int.

Syntax of Math.round() Method

double doubleValue = 52.6345;
int intValue = (int) Math.round(doubleValue);

Now, let’s look at an example that convert double to int in Java using Math.round() method.

Code Implementation:

class PrepBytes {
    public static void main(String args[])
    {
        double data1 = 52.6345;
        System.out.println("Double : " + data1);

        int value1 = (int)Math.round(data1);

        System.out.println("Integer : " + value1);
    }
}

Output:

Double: 52.6345
Integer: 53

Explanation: In the above example, we declare a class named "PrepBytes" with a "main" method. The "main" method begins by creating a double variable named "data1" and assigning it the value of 52.6345. Next, the program uses the Math.round() method to round the double value of "data1" to the nearest integer value. The rounded value is then explicitly cast to an integer variable "value1" using an explicit cast.

Approach 3: Using Double.intValue() Method

The Double class in Java provides a method called intValue() that returns the int value of a Double object. We can use this method to convert a double value to an int value. When we use the Double.intValue() method to convert a double to an int, the decimal part of the double value is truncated, i.e., it is simply removed.

Syntax of Double.inValue() method

double data = 52.6345
Double newData = new Double(data);
int value = newData.intValue();

Now, let’s look at an example that converts double to int in Java using the Double.intValue() method.

class PrepBytes {
    public static void main(String args[])
    {

        Double data = 52.6345;
        
        System.out.println("Double - " + data);
        
        Double newData = new Double(data);

        int value = newData.intValue();

        System.out.println("Double - " + value);
    }
}

Output:

Double - 52.6345
Double - 52

Explanation: In the above example, we created a class named "PrepBytes" with a "main" method. The "main" method starts by creating a Double variable "data" and assigning it the value 52.6345. Next, the program creates a new Double object "newData" by passing "data" as a parameter to the constructor of the Double class. The program then converts the Double object "newData" to an integer value using the intValue() method, which returns the integer value of the Double object.

Conclusion
Converting a double to an int in Java is a straightforward process, but it requires an understanding of how Java handles data types and the potential loss of information due to truncation. Whether you use explicit casting, the Math.round() method, or other techniques, it’s important to choose the right method based on your specific needs. By mastering these conversion techniques, you can ensure that your Java programs handle numeric data accurately and efficiently, regardless of the context in which you’re working.

FAQs related to how to convert double to int in Java

Here are some frequently asked questions on how to convert double to int in Java.

1. What happens when I cast a double to an int in Java?
When you cast a double to an int in Java, the fractional part of the double is truncated, and only the integer part is retained. For example, casting 12.99 to int will result in 12.

2. How can I round a double to the nearest int before converting?
You can round a double to the nearest int using the Math.round() method. For instance, Math.round(12.5) will return 13, and Math.round(12.4) will return 12.

3. Can I lose data when converting a double to an int?
Yes, you can lose data when converting a double to an int because the decimal (fractional) part is discarded during the conversion. For example, 12.99 will be truncated to 12, losing the 0.99.

4. Is there a way to handle the lost precision when converting double to int?
To handle lost precision, you can either round the double value before conversion using Math.round(), or you can consider whether storing the original double value separately might be necessary for your application.

5. What are the common methods to convert a double to an int in Java?
The common methods to convert a double to an int in Java include explicit casting (int), using Math.round() for rounding to the nearest integer, and using Math.floor() or Math.ceil() for flooring or ceiling the value to the nearest lower or higher integer, respectively.