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私は私のハッシュマップstudentMapのキーをハッシュしている私のリニアメソッドで衝突を検出しようとしています。私は線形プロービングのための基本的な機能を持っていますが、キーがすでに存在するかどうかを検出するために苦労しています（したがって+ 1）。これまでのところ、このコードは機能しません。地図のStudentMapからそのキーが存在するかどうかをチェックしません。 ご迷惑をおかけして申し訳ありません。他のハッシュメソッドのいくつかを削除して、このコードのサイズを無関係にするようにしました。衝突の分解線形プロービングJava
public class Main {
Student student;
public static boolean vartrue;
HashMap next;
public HashMap<String,Student> studentMap;
public static void main(String[] args) throws NoSuchFieldException, IllegalArgumentException, IllegalAccessException, NoSuchFieldException {
HashMap<String, String> studentMap = new HashMap<>(16, 0.75f);
//et keys and value
studentMap.keySet().forEach((key) -> {
String value = studentMap.get(key);
System.out.println("Key = " + key + ", Value = " + value);
});
//adding values to array
studentMap.put("16012804", "Jennifer");
studentMap.put("13747732", "Beatrice");
studentMap.put("14056983", "Mavis");
studentMap.put("16013464", "Geoffrey");
studentMap.put("14058392", "Bob");
studentMap.put("15405833", "Bill");
studentMap.put("14058039", "Gertrude");
studentMap.put("13056496", "Dorothy");
//iterating through the array
Set set = studentMap.entrySet();
Iterator iterator = set.iterator();
while(iterator.hasNext()) {
Map.Entry mapentry = (Map.Entry)iterator.next();
System.out.print("Key is: "+ mapentry.getKey() + " & Value is: ");
System.out.println(mapentry.getValue());
}
//Get values based on key
String var= studentMap.get("16012804");
System.out.println("Value at index 1 is: "+var);
// Remove values based on key
studentMap.remove("16012804");
System.out.println("Map key and values after removal:");
Set set2 = studentMap.entrySet();
Iterator iterator2 = set2.iterator();
while(iterator2.hasNext()) {
Map.Entry mapentry2 = (Map.Entry)iterator2.next();
System.out.print("Key is: "+mapentry2.getKey() + " & Value is: ");
System.out.println(mapentry2.getValue());
}
Set keyset = studentMap.keySet();
System.out.println("Key set values are:" + keyset);
boolean val = studentMap.isEmpty();
System.out.println("Is hash map empty: " + val);
//get values
Collection<String> values = studentMap.values();
System.out.println("Map values = " + values);
//size of table
System.out.println("Size of the Hashtable: " + studentMap.size());
//initial capacity
System.out.println("Initial Capacity: " + 16);
//capacity of map
System.out.println("Map capacity: " + mapcapacity(studentMap));
//load factor
System.out.println("Load Factor: " + loadFactor(studentMap));
//linear probing
System.out.println("...");
System.out.println("Hash Value(\"Jennifer\")="+ linear(studentMap, "16012804"));
System.out.println("Hash Value(\"Mavis\")="+ linear(studentMap, "14056983"));
System.out.println("Hash Value(\"Geoffrey\")="+ linear(studentMap, "16013464"));
System.out.println("Hash Value(\"Bill\")="+ linear(studentMap, "15405833"));
System.out.println("Hash Value(\"Gertrude\")="+ linear(studentMap, "14058039"));
System.out.println("Hash Value(\"Beatrice\")="+ linear(studentMap, "13747732"));
System.out.println("Hash Value(\"Bob\")="+ linear(studentMap, "14058392"));
if (vartrue = true)
{
Map<String, String> map1 = new HashMap<>(mapcapacity(studentMap) * 2);
map1.putAll(studentMap);
//capacity of the new hash map. (reflection)
System.out.println("Map 1 mappings= " + map1);
Field tableField = HashMap.class.getDeclaredField("table");
tableField.setAccessible(true);
Object[] table = (Object[]) tableField.get(map1);
System.out.println("Size of Map 1: ");
System.out.println(table == null ? 0 : table.length);
}
}
//when to increase the hashmap size is calculated by capacity of hashmap divided by load factor:
public static double loadFactor(Map studentMap){
double count = studentMap.size();
double load = count/mapcapacity(studentMap);
return load;
}
//if the size of the map is greater than the map capacity * load factor - then double the size of map.
public static Integer mapcapacity(Map studentMap){
//default capacity and load factor
Integer initCapacity= 11;
float loadFactor=0.75f;
boolean capacityFound=false;
Integer capacity=initCapacity;
Integer size=studentMap.size();
while(!capacityFound){
if(size>capacity*loadFactor){
//increase capacity
capacity=capacity * 2;
vartrue = true;
}
else {
capacityFound=true;
}
}
return capacity;
}
//linear probing
public static int hashThis(String key, Map studentMap) {
return key.hashCode()& 0x7fffffff % mapcapacity(studentMap);
}
public static int linear(Map studentMap, String key){
String value = studentMap.get(key).toString();
int counter = 0;
int hash = hashThis(key, studentMap);
if (value != null)
{
hash = (hash + 1) % mapcapacity(studentMap);
counter ++;
}
else{
return 0;
}
return hash;
}
}