Question

I have three List<String> variables: classFiles, usernames, and fileDirectories. I have a String (a list of strings but I will be comparing every string in the list with the loop below) that consists of one item from each of the lists. I want to loop through all three lists and check if one value from all three of the lists are in the String

What would be the best way to go about this?

for(String classFile:classFiles) {
//if contains classfile statement
  for(String username:usernames) {
  //if contains username statement
    for(String fileDirectory:fileDirectories) {
      //if contains filedirectory statement
    }
  }
}

or

for(String classFile:classFiles) {
  for(String username:usernames) {
    for(String fileDirectory:fileDirectories) {
      //if statement
    }
  }
}

or

for(String classFile:classFiles) {
  //make list of files that contain classFile
}

for(String username:usernames) {
  //remove items from list that do not contain username
}

for(String fileDirectory:fileDirectories){
  //remove items from list that do not contain fileDirectory
}

Or is there a better way to do this?

EDIT: Example

classFiles - a1, a2, a3
usernames - noc1, noc2, noc3
fileDirectories - C:/projects/a1/noc1/example.java, C:/projects/a1/ad3/example.java

and the string to check

String - C:/bin/a1/noc1/example.class

what i want to do is if both the fileDirectory and String contain a classFile and username, then add it to a list

so in this example C:/bin/a1/noc1/example.class will be added to the list but C:/bin/a4/fd1/example.class wont be or C:/bin/a3/noc3/example.class would not be added

Answer 1

When you perform remove operations for-each loop is not best choice. You should use Iterator and remove on iterator to avoid concurrent modification exception.

Instead

for(String fileDirectory:fileDirectories){
  //remove items from list that do not contain fileDirectory
}

You should do something like

Iterator iter = fileDirectores.iterator();
while(iter.hasNext())
{
//Get next
//Do your check 
iter.remove();
}

This leads to having three separate iterates to full fill your requirement.