remove this useless assignment to local variable sonar fix java

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Useless assignment to local variable ¶

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A value is assigned to a local variable, but either that variable is never read later on, or its value is always overwritten before being read. This means that the original assignment has no effect, and could indicate a logic error or incomplete code.

Recommendation ¶

Ensure that you check the program logic carefully. If a value is really not needed, consider omitting the assignment. Be careful, though: if the right-hand side has a side effect (like performing a method call), it is important to keep this to preserve the overall behavior.

The following example shows six different types of assignments to local variables whose value is not read:

In ParseInt , the result of the call to int.TryParse is assigned directly to the unread local variable success .

In IsDouble , the out argument of the call to int.TryParse is assigned to the unread local variable i .

In ParseDouble , the exception thrown by the call to double.Parse in case of parse failure is assigned to the unread local variable e .

In Count , the elements of ss are assigned to the unread local foreach variable s .

In IsInt , o is assigned (in case o is an integer) to the unread local type test variable i .

In IsString , o is assigned (in case o is a string) to the unread local type case variable s .

The revised example eliminates the unread assignments.

References ¶

Wikipedia: Dead store .

MSDN, Code Analysis for Managed Code, CA1804: Remove unused locals .

Microsoft: What’s new in C# 7 - Discards .

Common Weakness Enumeration: CWE-563 .

Solving Sonar's 'Remove Useless Assignment of Local Variable' Error in Swift

Abstract: Learn how to resolve SonarQube's 'Remove Useless Assignment of Local Variable' error in Swift by understanding its cause and using different workarounds.

Solving Sonar's "Remove Useless Assignment to Local Variable" Error in Swift

Sonar is a popular tool used for code analysis and review. It helps developers identify and fix issues in their code, making it more readable, maintainable, and secure. One common issue that Sonar flags is the "Remove Useless Assignment to Local Variable" error in Swift. This error occurs when a local variable is assigned a value that is not used in the code. In this article, we will discuss how to solve this error in Swift.

Understanding the Error

To understand the error, let's consider an example:

In this example, we declare two local variables, x and y. We assign the value 5 to x and then calculate the value of y by multiplying x by 2. However, we never use the value of x again in the code. Therefore, Sonar flags the assignment of x as a useless assignment.

Solving the Error

To solve the error, we need to ensure that every local variable is used in the code. We can do this by either using the variable or removing its declaration. In the above example, we can remove the declaration of x, as it is not used in the code:

Alternatively, we can use the value of x in the code:

In this example, we print the value of x to the console, ensuring that it is used in the code.

Using Sonar to Identify Useless Assignments

Sonar can help us identify useless assignments in our code. To do this, we need to configure Sonar to analyze our Swift code. We can do this by installing the SonarSwift plugin and configuring it to analyze our project. Once we have done this, Sonar will flag any useless assignments in our code, allowing us to fix them.

The "Remove Useless Assignment to Local Variable" error in Swift is a common issue that Sonar flags. To solve this error, we need to ensure that every local variable is used in the code. We can do this by either using the variable or removing its declaration. Sonar can help us identify useless assignments in our code, allowing us to fix them and improve the quality of our code.

Remove Useless Assignment to Local Variable

Supported Languages

Tags: :  Swift SonarQube Software Development

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"Remove this useless assignment to local variable", but the assignment is not useless

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Michael Gumowski

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SonarLint : Unused local variables should be removed

If there are some variables that are usually used by the developers for debugging but later those variables are not used. Those variables should be removed since it is a dead code.It will improve the maintainability and other developers will not wonder where this local variable is used.

Example from sonar lint

Noncompliant Code Example

Compliant solution.

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Remove this useless assignment to local variable - sonarqube - using try catch

In the following code, sonarqube is complaining for the mentioned error in the question:

How can I re-write this code to resolve this complain from sonarqube?

• 1 Does your catch block rethrow? Can you provide a minimal reproducible example example rather then just commented bits? –  Jon Skeet Commented Nov 25, 2020 at 11:15
• @Jon I have provided the exact code. –  teenup Commented Nov 25, 2020 at 11:17
• 1 Have you tried not having a result at all and doing a return await func() / return default(T) instead? –  Caius Jard Commented Nov 25, 2020 at 11:18
• 2 I could assume that it's complaining about T result = default; but why are you making me guess? –  Damien_The_Unbeliever Commented Nov 25, 2020 at 11:19
• 1 @TimSchmelter: How is it redundant? If func() throws an exception or the task it returns throws an exception, there'd be no value in result . Without the initial assignment, the variable isn't definitely assigned at the return statement. –  Jon Skeet Commented Nov 25, 2020 at 11:19

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