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Bug 362415

Summary:	New warning to detect unnecessary toString() on String
Product:	[Eclipse Project] JDT	Reporter:	Paul Benedict <pbenedict>
Component:	Core	Assignee:	Ayushman Jain <amj87.iitr>
Status:	NEW ---	QA Contact:
Severity:	enhancement
Priority:	P3	CC:	amj87.iitr, avijayr, deepakazad, ulrich.everling
Version:	3.8
Target Milestone:	---
Hardware:	PC
OS:	Windows 7
Whiteboard:

Description Paul Benedict

2011-10-29 23:03:02 EDT

Build Identifier: 20110916-0149

After doing some method refactoring, I ended up with code that had toString() calls on a returning String. 

Before:
String s = returnsUUID().toString();
After:
String s = returnsString().toString();

That's redundant code. It would be nice to catch these kind of useless calls for String.toString() with a compiler warning option.

Reproducible: Always

Comment 1 Deepak Azad

2011-10-31 14:53:50 EDT

This is essentially a search for method references and hence I would rather fix bug 209145 as that would be a more general solution for all methods.

Comment 2 Deepak Azad

2011-10-31 14:55:37 EDT

Also note that a call to String#toString() is harmless as the method is defined as..

public String toString() {
	return this;
}

Comment 3 Paul Benedict

2011-10-31 15:05:29 EDT

If bug 209145 can be fixed, perhaps then Clean Up could be enhanced to remove these spurious invocations.

Comment 4 Missing name Mising name

2011-12-08 03:37:05 EST

This is independent of bug #209145 because String is final so toString() cannot be overridden.

The warning should be raised for x.toString() whenever x is an expression of type java.lang.String

The Quick Fix should remove the method call, leaving x alone.

Of course x is not entirely equivalent with x.toString() because,
when x happens to evaluate to null, x.toString() throws a NullPointerException.

Comment 5 Ayushman Jain

2011-12-08 04:29:18 EST

*** Bug 44787 has been marked as a duplicate of this bug. ***

Comment 6 Missing name Mising name

2011-12-08 09:50:23 EST

When x is an expression of type String, and x.toString() is used as a StatementExpression, then x alone may or may not be suitable as a StatementExpression.
If not, the Quick Fix of omitting the method call and keeping x is inappropriate; instead, a quick fix should consider omitting x as well but keeping side effects if any.

The warning itself makes sense anyway.