Create an array containing the keys in a map : Map « Collections « Java Tutorial






  1. Java Tutorial
  2. Collections
  3. Map
import java.util.HashMap;
import java.util.Map;

public class Main {
  public static void main(String[] argv) throws Exception {
    Map map = new HashMap();

    Object[] objectArray = map.keySet().toArray();
    MyClass[] array = (MyClass[]) map.keySet().toArray(new MyClass[map.keySet().size()]);

  }
}

class MyClass {
}








9.25.Map
9.25.1.Creating and storing arrays in a map
9.25.2.Sort based on the values
9.25.3.Get a key from value with an HashMap
9.25.4.Retrieve environment variables (JDK1.5)
9.25.5.Creating a Type-Specific Map: creates a map whose keys are Integer objects and values are String objects.
9.25.6.A map declared to hold objects of a type T can also hold objects that extend from T
9.25.7.A value retrieved from a type-specific collection does not need to be casted
9.25.8.Map techniques.
9.25.9.Create an array containing the keys in a map
9.25.10.Create an array containing the values in a map
9.25.11.Creating a Hash Table
9.25.12.Creating a Map That Retains Order-of-Insertion
9.25.13.Automatically Removing an Unreferenced Element from a Hash Table
9.25.14.Creating a Type-Specific Map [5.0]
9.25.15.Create type specific collections
9.25.16.Convert Properties into Map