• DLS_DEAD_LOCAL_INCREMENT_IN_RETURN

“This statement has a return such as return x++;. A postfix increment/decrement does not impact the value of the expression, so this increment/decrement has no effect. Please verify that this statement does the right thing. ” – 2013-11-24

A postfix increment in java (such as i++) does the following: - it takes i - stores a copy - adds 1 - returns the copy

That means the expression i++ returns i and not i + 1. <code Java> int i = 5; i++; System.out.println(i); 6 System.out.println(i++); 6 </Code>

Whenever a methods return expression is i++ (or i–) the postfix increment/decrement does effectively nothing since the return value is not changed and the variable will be lost. This is very likely to be a logical error.

<code Java> public int getNumber(){

int x = 5;
return x++;

}

public int decrement(int y){

return y--;

} </Code>

<code Java> public int getNumber(){

int x = 5;
x++;
return x;

}

Prefix decrements however do effect the return value of the expression public int decrement(int y){ return –y; } </Code> ===== Evaluation Results ===== ^ Benchmark project ^ Time ^ # Hits Precision ^ Recall ^ | || FB | JT | FB | JT | Delta | FB | JT | Delta | | Apache Tomcat |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | Argo UML |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | AWT |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | Jakarta |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | Java IO |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | JHotDraw |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | jrefactory |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | JServlet |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | JUnit |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | Lexi |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | Mapper XML |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | nutch |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | PMD |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | | quickuml |< 1s|0|0| 100% | 100% | 0 | 100% | 100% | 0 | FB = FindBugs, JT = JTransformer, Delta = JTransformer - FindBug All measurements were taken on a machine with the following properties: * JT Version: 4.0.0 * Eclipse Kepler * Windows 8.1 * i5 2,30Ghz * 8 GB Main Memory * SSD Hardrive