Source of 20.5.java

Structures and functions

  1: public V add(K key, V value)
  2: {
  3:    checkInitialization();
  4:    if ((key == null) || (value == null))
  5:       throw new IllegalArgumentException("Cannot add null to a dictionary.");
  6:    else
  7:    {
  8:       V result = null;
  9:       int keyIndex = locateIndex(key);
 10:       if (keyIndex < numberOfEntries)
 11:       {
 12:          // Key found, return and replace entry's value
 13:          result = dictionary[keyIndex].getValue(); // Get old value
 14:          dictionary[keyIndex].setValue(value);                 // Replace value
 15:       }
 16:       else // Key not found; add new entry to dictionary
 17:       {
 18:          // Add at end of array
 19:          dictionary[numberOfEntries] = new Entry<>(key, value);
 20:          numberOfEntries++;
 21:          ensureCapacity(); // Ensure enough room for next add
 22:       } // end if
 23:       return result;
 24:    } // end if
 25: } // end add
 26: 
 27: // Returns the array index of the entry that contains key, or
 28: // returns numberOfEntries if no such entry exists.
 29: private int locateIndex(K key)
 30: {
 31:    // Sequential search
 32:    int index = 0;
 33:    while ( (index < numberOfEntries) && !key.equals(dictionary[index].getKey()) )
 34:       index++;
 35:    return index;
 36: } // end locateIndex
 37: // Version 4.0