java.io.File构造函数行为还是多线程问题？

I have the following code:

我有以下代码:

class Abcd{
//wired by spring to give the directory filePath ="/var/tmp/"
private String filePath;

 public void myMethod(String id, String date){
  filePath= filePath+ id+ "_" + date;
  File f = new File(filePath);
  if(f.exists){//Do something}
  else{
   System.out.println("File not found at file path:"+filePath);
  }
 }
}
class Ab