What Causes 'Possible Lossy Conversion' Errors in Java and How Can They Be Fixed?

What is "possible lossy conversion" and how can it be resolved?

When attempting to implicitly convert between numeric primitive types, Java may issue an error message indicating "possible lossy conversion." This occurs when the target type is smaller than the original type, potentially resulting in data loss.

Understanding Lossy Conversions:

• A lossy conversion can happen, for example, when converting an int to a byte, as some int values can't be represented in the smaller byte type.
• However, converting from a long to a float is not lossy, as all long values have corresponding float representations.

Resolving the Error:

To resolve the error, a typecast is typically used to force the conversion. For instance:

int squareRoot = (int) Math.sqrt(i);

Analyzing the Root Cause:

Before adding a typecast, it's crucial to determine why the conversion is needed:

• Is it due to an underlying error in the code?
• Should the original type be modified to avoid the lossy conversion?
• Is a typecast the best solution for the specific application, or are other options like throwing an exception more appropriate?

Possible Lossy Conversions During Array Subscription:

Assigning a double to an array index will trigger the error. Since array indices must be integers, a lossy conversion occurs. Instead, ensure the index is an integer type.

Possible Lossy Conversions in Method/Constructor Calls:

A similar error occurs when passing arguments of a different type than the method/constructor expects. For example, passing an int to a parameter declared as short requires a typecast to avoid the lossy conversion.

Possible Lossy Conversions in Return Statements:

Assigning a smaller type (e.g., int) to a return type declared as a larger type (e.g., long) can trigger the error. Either a typecast or changing the return type can address this.

Possible Lossy Conversions Due to Promotion:

Arithmetic and bitwise operators for integer types promote results to an int or long, potentially causing a lossy conversion. Typecasting back to the desired type is necessary in such cases.

Possible Lossy Conversions When Assigning Literals:

Assigning an int literal to a byte variable may lead to the error if the value is not representable as a byte without loss. However, assigning the same literal to a byte variable is allowed if the value fits within the byte range.

The above is the detailed content of What Causes 'Possible Lossy Conversion' Errors in Java and How Can They Be Fixed?. For more information, please follow other related articles on the PHP Chinese website!