Create a typesafe copy of a raw map. : Generic Collection « Generics « Java






Create a typesafe copy of a raw map.

   
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import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;

/**
 * @since 4.37
 * @author Jaroslav Tulach
 */


public class Utils {

  /**
   * Create a typesafe copy of a raw map.
   * @param rawMap an unchecked map
   * @param keyType the desired supertype of the keys
   * @param valueType the desired supertype of the values
   * @param strict true to throw a <code>ClassCastException</code> if the raw map has an invalid key or value,
   *               false to skip over such map entries (warnings may be logged)
   * @return a typed map guaranteed to contain only keys and values assignable
   *         to the named types (or they may be null)
   * @throws ClassCastException if some key or value in the raw map was not well-typed, and only if <code>strict</code> was true
   */
  public static <K,V> Map<K,V> checkedMapByCopy(Map rawMap, Class<K> keyType, Class<V> valueType, boolean strict) throws ClassCastException {
      Map<K,V> m2 = new HashMap<K,V>(rawMap.size() * 4 / 3 + 1);
      Iterator it = rawMap.entrySet().iterator();
      while (it.hasNext()) {
          Map.Entry e = (Map.Entry) it.next();
          try {
              m2.put(keyType.cast(e.getKey()), valueType.cast(e.getValue()));
          } catch (ClassCastException x) {
              if (strict) {
                  throw x;
              } else {
                  System.out.println("not assignable");
              }
          }
      }
      return m2;
  }
}

   
    
    
  








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