PMD is a source code analyzer. It finds common programming flaws like unused variables, empty catch blocks, unnecessary object creation, and so forth. It supports Salesforce.com 
Apex, Java, JavaScript, XML, XSL.
PMD是一个源代码分析工具，可以发现通常的编程缺陷，如无用变量，空catch块，不需要的对象创建等。支持Salesforce.con，Apex，Java，JavaScript，XML和XSL。
Additionally it includes CPD, the copy-paste-detector. CPD finds duplicated code in Java, C, C++, C#, PHP, Ruby, Fortran, JavaScript, Matlab, Swift.
此外，还包括CPD——拷贝粘贴检查，发现重复代码，支持Java, C, C++, C#, PHP, Ruby, Fortran, JavaScript, Matlab, Swift.等编程语言。