class Name1 listing, partial rewriting of Singleton pattern introduction

This commit is contained in:
Volodymyr Karpenko 2022-10-20 19:21:24 +02:00
parent 00efe7d4b0
commit d07e2d2889
2 changed files with 40 additions and 2 deletions

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@ -168,12 +168,50 @@ submission as the file \textit{analysis.xml}.
\section{Structural Patterns} \section{Structural Patterns}
\subsection{TO REWRITE Singleton Pattern} \subsection{TO REWRITE Singleton Pattern}
Lots of false positives for the Singleton pattern. Example, Ensure a class only has one instance and provide a global point of access to it.
com.fasterxml.jackson.core.sym.Name1 has a package private constructor and a The tool found thirteen instances with the Singleton pattern,
doing a deeper analysis of the found instances we discovered that some of the results are false positives.
Example, com.fasterxml.jackson.core.sym.Name1 has a package private constructor and a
public static final instance of it, but reading the documentation the class public static final instance of it, but reading the documentation the class
represents (short) JSON string literals and therefore is clearly represents (short) JSON string literals and therefore is clearly
initialized by client code. initialized by client code.
\begin{lstlisting}[caption=Name1 class,language=java]
public final class Name1 extends Name {
private final static Name1 EMPTY = new Name1("", 0, 0);
private final int q;
Name1(String name, int hash, int quad) {
super(name, hash);
q = quad;
}
public static Name1 getEmptyName() {
return EMPTY;
}
@Override
public boolean equals(int quad) {
return (quad == q);
}
@Override
public boolean equals(int quad1, int quad2) {
return (quad1 == q) && (quad2 == 0);
}
@Override
public boolean equals(int q1, int q2, int q3) {
return false;
}
@Override
public boolean equals(int[] quads, int qlen) {
return (qlen == 1 && quads[0] == q);
}
}
\end{lstlisting}
(com.fasterxml.jackson.core omitted for brevity) (com.fasterxml.jackson.core omitted for brevity)
\begin{description} \begin{description}