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Tool to Find Duplicate values in Constants

Jul 30, 2015 - 2 minute read - Comments - sampletooljavaduplicategmaurlibrary

Imagine having this java class:

private static class RepeatedConstants {
    public static final String A = "A";
    public static final String A_1 = A;
    public static final String A_2 = "A";

    public static final Integer _3 = 3;
    public static final Integer THREE = 3;

I wanted to remove the repeated values in the constants, in an automatic way, because the file was big (> 4000 constants). A way of doing this is basing the differences on the values, directly. To do this, remove all text that is not a value:

find what, regex mode: ^.*=\s*(.*); replace with: $1


  • ^.*=\s*: any character before the equal sign. Any whitespace right after it.
  • (.*);: capture everything that is before the semicolon (;)

You end up with this:



Copy it to a.txt, sort it and uniq it (to remove duplication):

cat a.txt | sort | uniq > uniq.txt

then sort the non-uniq version:

cat a.txt | sort > sorted.txt

and diff among them, to find the repeated values:

diff sorted.txt uniq.txt

< "A"
< 3

These are the repeated values. The variable public static final String A_1 = A; was not caught by this as it only has the same value in execution, not staticly.

For this, at Gmaur, we have developed a small module to detect duplicates. The main code is this:

public class RepeatedFinder {

  private final Class aClass;

  public RepeatedFinder(Class aClass) {
    this.aClass = aClass;

  public MultiMap findDuplicates() throws IllegalAccessException {
    return generateMapFromValueToVariables(aClass).valuesWithMoreThanOneVariable();

  private ValueToNameRepository generateMapFromValueToVariables(Class<?> clazz) throws IllegalAccessException {
    ValueToNameRepository valueToNames = new ValueToNameRepository();
    Field[] fields = clazz.getDeclaredFields();
    Object object = new Object();
    for (Field field : fields) {
      Object value = field.get(object);
      valueToNames.add(value, field.getName());
    return valueToNames;

The tests and the source code can be found here:

Hope you enjoy it, as much as we have enjoyed writing it!

Any feedback is welcome.

Tip: Use the same Import Order in IntelliJ IDEA as Eclipse's Packing your own maven dependencies

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