遍历Map条目时如何避免DuplicateFormatFlagsException

Question

Given a Map< String, Enum >, how can I Iterate through the entries, using the Map's keySet() and display the value? I'm only familiar with four methods of Map iteration; I can get three to work and I'm uncertain why the remaining one throws an exception.

I've tried implementing a custom Gender.toString() method, retyping the Set<> & Map values, and inline casting of the Gender value to String.

Hopefully I'm just missing something obvious but a half hour of searching yielded me no answer. Likely I'm wording the question wrong. Hopefully this code can describe my question better.

public enum Gender { MALE, FEMALE; }

public static void main (String[] args)
{
    Map<String,Gender> humans = new HashMap<String,Gender>();

    humans.put("Samuel", Gender.MALE);
    humans.put("Bryce", Gender.MALE);
    humans.put("Conrad", Gender.MALE);
    humans.put("Angie", Gender.FEMALE);

    System.out.println("for .keyset()");
    Set<String> ks = humans.keySet();
    for (String key : ks)
    {
        System.out.printf("Key: %s  Value: %s\n", key, humans.get(key));
    }

    System.out.println("\nfor .entrySet() ");
    Set<Map.Entry<String,Gender>> entrySet = humans.entrySet();
    for (Map.Entry entry : entrySet)
    {
        System.out.printf("Key: %s  Value: %s\n", entry.getKey(), entry.getValue());
    }

    // ***---> FAILS with DuplicateFormatFlagsException
    System.out.println("\nwhile .keyset().iterator()");
    Set<String> ks2 = humans.keySet();
    Iterator<String> keySetIterator = ks2.iterator();
    while (keySetIterator.hasNext())
    {
        String key= keySetIterator.next();
        System.out.printf("Key: %  Value: %s\n", key, humans.get(key) ); // fault line
    }

    System.out.println("\nwhile .entrySet().iterator()");
    Set<Map.Entry<String,Gender>> entrySet2 = humans.entrySet();
    Iterator<Map.Entry<String,Gender>> entrySetIterator = entrySet2.iterator();
    while (entrySetIterator.hasNext())
    {
        Map.Entry<String,Gender> entry = entrySetIterator.next();
        System.out.printf("Key: %s  Value: %s\n", entry.getKey(), entry.getValue() );
    }
}

Any input will be greatly appreciated. Thank you!

Answer 1

Derp's on me... After posting my question I noticed the typo. I forgot the converter after the %.

System.out.printf("Key: %  Value: %s\n", key, humans.get(key) ); // fault line

Should be

System.out.printf("Key: %s  Value: %s\n", key, humans.get(key) ); // fault line