java HashMap put method implementation. My code is.. /** * Adds the given key-value pair to the HashMap.  * If an entry in the HashMap already has this key, replace the entry's  * value with the new one passed in.  *  * In the case of a collision, use linear probing as your resolution  * strategy.  *  * Check to see if the backing array needs to be regrown BEFORE adding. For  * example, if my HashMap has a backing array of length 5, and 3 elements in  * it, I should regrow at the start of the next add operation (even if it  * is a key that is already in the hash map). This means you must account  * for the data pending insertion when calculating the load factor.  *  * When regrowing, increase the length of the backing table by  * 2 * old length + 1. Use the resizeBackingTable method.  *  * Return null if the key was not already in the map. If it was in the map,  * return the old value associated with it.  *  * @param key key to add into the HashMap  * @param value value to add into the HashMap  * @throws IllegalArgumentException if key or value is null  * @return null if the key was not already in the map. If it was in the  * map, return the old value associated with it  */ @Override public V put(K key, V value) { if (key == null || value == null) { throw new IllegalArgumentException("Key or Value cannot be null"); } if (size + 1 >= (MAX_LOAD_FACTOR * table.length)) { resizeBackingTable(table.length * 2 + 1); } int hash = Math.abs(key.hashCode() % table.length); int curr = 0; int firstDel = table.length; while (true) { if (curr >= table.length) { if (firstDel != table.length) { table[firstDel] = new MapEntry(key, value); return null; } resizeBackingTable(table.length * 2 + 1); curr = 0; } int index = (int) (hash + Math.pow(curr, 2)) % table.length; if (table[index] == null) { table[index] = new MapEntry(key, value); size++; return null; } else if (table[index].isRemoved() && firstDel == table.length) { firstDel = index; } else if (table[index].getKey().equals(key) && table[index].isRemoved()) { table[index] = new MapEntry(key, value); size++; return null; } else if (table[index].getKey().equals(key)) { V retValue = table[index].getValue(); table[index] = new MapEntry(key, value); return retValue; } curr++; } } 

and this is result of my test..

/unchecked/ public void testPut() directory = new HashMap( initialCapacity: 5); MapEntrycInteger, string>[] exp= (MapEntry [ ] ) assertEquals( expected: 0, directory.size()); assertArrayEquals(exp, directory.getTable()); (new MapEr assertEquals( expected: null, directory.put (3, "Luke")); exp [3] = new MapEntryc>(3, "Luke"); assertEquals( expected: 1, directory.size()); assertArrayEquals(exp, directory.getTable()); assertEquals( expected: null, directory.put (13, "Han")); exp [4] = new MapEntryc2(13, "Han"); assertEquals( expected: 2, directory.size()); assertArrayEquals(exp, directory.getTable()); assertEquals( expected: null, directory.put(8, "Chewbacca")); exp[0] = new MapEntryc> (8, "Chewbacca"); assertEquals( expected: 3, directory.size()); assertArrayEquals(exp, directory.getTable()); exp = (MapEntry[]) (new MapEntry[11]); assertEquals( expected: null, directory.put(-5, "Leia")); exp [2] = new MapEntryc2(13, "Han"); exp [3] = new MapEntryc> (3, "Luke"); exp [5] = new MapEntryc> (-5, "Leia"); exp[8] new MapEntry (8, "Chewbacca"); assertEquals( expected: 4, directory.size()); assertArrayEquals(exp, directory.getTable()); HashMapStudentTests testPut(0 22 tests done: 6 fa arrays first differed at element [0]; Expected :8: Chewbacca Actual null at HashMapStudentTests. testPut (HashMapStudentTests.java :96) 11 internal ci Caused by: java. lang.AssertionError: expected: but was: 16 more /unchecked/ public void testPut() directory = new HashMap( initialCapacity: 5); MapEntrycInteger, string>[] exp= (MapEntry [ ] ) assertEquals( expected: 0, directory.size()); assertArrayEquals(exp, directory.getTable()); (new MapEr assertEquals( expected: null, directory.put (3, "Luke")); exp [3] = new MapEntryc>(3, "Luke"); assertEquals( expected: 1, directory.size()); assertArrayEquals(exp, directory.getTable()); assertEquals( expected: null, directory.put (13, "Han")); exp [4] = new MapEntryc2(13, "Han"); assertEquals( expected: 2, directory.size()); assertArrayEquals(exp, directory.getTable()); assertEquals( expected: null, directory.put(8, "Chewbacca")); exp[0] = new MapEntryc> (8, "Chewbacca"); assertEquals( expected: 3, directory.size()); assertArrayEquals(exp, directory.getTable()); exp = (MapEntry[]) (new MapEntry[11]); assertEquals( expected: null, directory.put(-5, "Leia")); exp [2] = new MapEntryc2(13, "Han"); exp [3] = new MapEntryc> (3, "Luke"); exp [5] = new MapEntryc> (-5, "Leia"); exp[8] new MapEntry (8, "Chewbacca"); assertEquals( expected: 4, directory.size()); assertArrayEquals(exp, directory.getTable()); HashMapStudentTests testPut(0 22 tests done: 6 fa arrays first differed at element [0]; Expected :8: Chewbacca Actual null at HashMapStudentTests. testPut (HashMapStudentTests.java :96) 11 internal ci Caused by: java. lang.AssertionError: expected: but was: 16 more