Hash table with linear probing : HashTable Map « Collections Data Structure « Java

1. Java
2. Collections Data Structure
3. HashTable Map

Hash table with linear probing

import java.io.IOException; publicclass HashTable { private DataItem[] hashArray; privateint 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  } publicvoid displayTable() { System.out.print("Table: "); for (int j = 0; j < arraySize; j++) { if (hashArray[j] != null) System.out.print(hashArray[j].getKey() + " "); else System.out.print("#"); } System.out.println(""); } publicint hashFunction(int key) { return key % arraySize; } publicvoid 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 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  } publicstaticvoid main(String[] args) throws IOException { DataItem aDataItem; int aKey, size, initSize, keysPerCell; size = 150; initSize = 100; keysPerCell = 10; HashTable theHashTable = new HashTable(size); for (int j = 0; j < initSize; j++){ aKey = (int) (java.lang.Math.random() * keysPerCell * size); aDataItem = new DataItem(aKey); theHashTable.insert(aDataItem); } theHashTable.displayTable(); aDataItem = new DataItem(100); theHashTable.insert(aDataItem); theHashTable.delete(100); aDataItem = theHashTable.find(100); if (aDataItem != null) { System.out.println("Found " + 100); } else System.out.println("Could not find " + 100); } } class DataItem { privateint data; public DataItem(int d) { data = d; } publicint getKey() { return data; } } 

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