How to Properly Cast a Double to an Integer in Java?

What is the correct method to cast a java.lang.Double to a java.lang.Integer in Java without causing a ClassCastException?

Double myDouble = 10.5;
int myInt = myDouble.intValue(); // Correct way to cast Double to Integer.

In Java, directly casting an object of type `Double` to `Integer` is not permissible, as Java does not support implicit conversion among its object types. This often leads to a `ClassCastException`. Instead, you should convert the `Double` to an `Integer` using appropriate methods provided by the Java API.

Double myDouble = 10.5;
int myInt = myDouble.intValue(); // Correctly converts Double to int

Causes

• Using direct casting with parentheses, e.g., `(Integer) myDouble`, which will throw a ClassCastException.
• Assuming Java's automatic boxing can handle this type conversion number.

Solutions

• Use the `intValue()` method of the `Double` class to retrieve the integer representation of the double value.
• Convert the double using `Math.round()` prior to casting if you need to round it to the nearest integer.
• Be cautious of type precision and rounding effects when converting from double to integer.

Mistake: Directly casting with (Integer) operation.

Solution: Use myDouble.intValue() instead of direct casting.

Mistake: Ignoring potential loss of precision when converting from double to integer.

Solution: Always check the value if precision is crucial or use rounding methods.

Mistake: Assuming Integer and Double types are interchangeable as primitives.

Solution: Understand the difference between wrapper classes and primitive types in Java.