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Archivierte Version vom 2012-03-18T15:36:29+00:00.
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public class HashTable { private DataItem[] hashArray; private int arraySize; // private DataItem bufItem; // for deleted items public HashTable(int size) { arraySize = size; hashArray = new DataItem[arraySize]; // bufItem = new DataItem(-1); // deleted item key is -1 } public void displayTable() { System.out.print("Hash Table: "); for (int i = 0; i < arraySize; i++) { if (hashArray[i] != null) System.out.print(hashArray[i].getKey() + " "); else System.out.print("# "); } System.out.println(""); } public int hashFunction(int key) { return key % arraySize; } public void insert(DataItem item) { int key = item.getKey(); int hashVal = hashFunction(key); // hash the key // until empty cell or -1, while (hashArray[hashVal] != null/* && hashArray[hashVal].getKey() != -1 */) { ++hashVal; // go to next cell hashVal %= arraySize; // wraparound if necessary } hashArray[hashVal] = item; // insert item } public DataItem delete(int key) { int hashVal = hashFunction(key); while (hashArray[hashVal] != null) // until empty cell, { if (hashArray[hashVal].getKey() == key) { // DataItem temp = hashArray[hashVal]; // save item // hashArray[hashVal] = bufItem; // delete item return hashArray[hashVal] = null; // return temp; } ++hashVal; // go to next cell hashVal %= arraySize; // wraparound if necessary } return null; // can't find item } public DataItem find(int key) // find item with key { int hashVal = hashFunction(key); // hash the key while (hashArray[hashVal] != null) // until empty cell, { if (hashArray[hashVal].getKey() == key) return hashArray[hashVal]; // found, return item ++hashVal; // go to next cell hashVal %= arraySize; // wraparound if necessary } return null; // can't find item } } class DataItem { private int data; public DataItem(int d) { data = d; } public int getKey() { return data; } }
DataItem aDataItem; int aKey, size; size = 15; HashTable theHashTable = new HashTable(size); aKey = 1; aDataItem = new DataItem(aKey); theHashTable.insert(aDataItem); aKey = 3; aDataItem = new DataItem(aKey); theHashTable.insert(aDataItem); aKey = 4; aDataItem = new DataItem(aKey); theHashTable.insert(aDataItem); aKey = 8; aDataItem = new DataItem(aKey); theHashTable.insert(aDataItem); aKey = 9; aDataItem = new DataItem(aKey); theHashTable.insert(aDataItem); aKey = 12; aDataItem = new DataItem(aKey); theHashTable.insert(aDataItem); aKey = 13; aDataItem = new DataItem(aKey); theHashTable.insert(aDataItem); theHashTable.displayTable(); aKey = 23; aDataItem = new DataItem(aKey); theHashTable.insert(aDataItem); theHashTable.displayTable(); theHashTable.delete(9); theHashTable.displayTable(); aDataItem = theHashTable.find(aKey); if (aDataItem != null) { System.out.println(aKey + " wurde gefunden!"); } else { System.out.println(aKey + " wurde nicht gefunden!"); }
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