How to iterate over a TreeMap

Question

Possible Duplicate    How do I iterate over each Entry in a Map        I want to iterate over a TreeMap  and for all keys which have a particular value  I want them to be added to a new TreeMap  How can I do this

User · Answer

Just to point out the generic way to iterate over any map    private  lt K  V gt  void iterateOverMap Map lt K  V gt  map        for  Map Entry lt K  V gt  entry   map entrySet              System out println  key - gt     entry getKey        value- gt     entry getValue

User · Answer

create TreeMap instance     TreeMap treeMap   new TreeMap           add key value pairs to TreeMap     treeMap put  1   One        treeMap put  2   Two        treeMap put  3   Three                  get Collection of values contained in TreeMap using       Collection values                      Collection c   treeMap values           obtain an Iterator for Collection     Iterator itr   c iterator           iterate through TreeMap values iterator     while itr hasNext          System out println itr next       or      for  Map Entry lt K V gt  entry   treeMap entrySet              V value   entry getValue            K key   entry getKey           or         Use iterator to display the keys and associated values    System out println  Map Values Before         Set keys   map keySet       for  Iterator i   keys iterator    i hasNext            Integer key    Integer  i next         String value    String  map get key        System out println key           value

User · Answer

Using Google Collections  assuming K is your key type   Maps filterKeys treeMap  new Predicate lt K gt         Override   public boolean apply K key        return false    return true here if you need the entry to be in your new map          You can use filterEntries instead if you need the value as well

User · Answer

Assuming type TreeMap lt String Integer gt     for Map Entry lt String Integer gt  entry   treeMap entrySet        String key   entry getKey      Integer value   entry getValue       System out println key       gt      value        key and Value types can be any class of course

[java] How to iterate over a TreeMap?

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