Java by API/java.util/Hashtable
Содержание
- 1 Hashtable: clear()
- 2 Hashtable: clone()
- 3 Hashtable: containsKey(Object key)
- 4 Hashtable: contains(Object value)
- 5 Hashtable: elements()
- 6 Hashtable: entrySet()
- 7 Hashtable: get(E e)
- 8 Hashtable: isEmpty()
- 9 Hashtable: iterator()
- 10 Hashtable: keys()
- 11 Hashtable: keySet()
- 12 Hashtable: putAll(Map<K,V> t)
- 13 Hashtable: put(K key, V value)
- 14 Hashtable: remove(Object key)
- 15 Hashtable: size()
- 16 Hashtable: values()
- 17 new Hashtable()
- 18 new Hashtable < K, V > ()
Hashtable: clear()
<source lang="java">
import java.util.Hashtable; public class Main {
public static void main(String[] s) {
Hashtable<String,String> table = new Hashtable<String,String>();
table.put("key1", "value1");
table.put("key2", "value2");
table.put("key3", "value3");
table.clear();
System.out.println(table);
}
}
</source>
Hashtable: clone()
<source lang="java">
import java.util.Hashtable; public class Main {
public static void main(String[] s) {
Hashtable<String,String> table = new Hashtable<String,String>();
table.put("key1", "value1");
table.put("key2", "value2");
table.put("key3", "value3");
Hashtable tableCopy = (Hashtable)table.clone();
System.out.println(tableCopy);
}
}
</source>
Hashtable: containsKey(Object key)
<source lang="java">
import java.util.Hashtable; public class Main {
public static void main(String[] args) {
Hashtable<String, String> ht = new Hashtable<String, String>();
ht.put("1", "One");
ht.put("2", "Two");
ht.put("3", "Three");
boolean blnExists = ht.containsKey("2");
System.out.println("2 exists in Hashtable ? : " + blnExists);
}
}
</source>
Hashtable: contains(Object value)
<source lang="java">
import java.util.Hashtable; public class Main {
public static void main(String[] s) {
Hashtable<String,String> table = new Hashtable<String,String>();
table.put("key1", "value1");
table.put("key2", "value2");
table.put("key3", "value3");
System.out.println(table.contains("value3"));
}
}
</source>
Hashtable: elements()
<source lang="java">
import java.util.Collection; import java.util.Enumeration; import java.util.Hashtable; import java.util.Iterator; public class Main {
public static void main(String[] args) {
Hashtable<String, String> ht = new Hashtable<String,String>();
ht.put("1", "One");
ht.put("2", "Two");
ht.put("3", "Three");
Collection c = ht.values();
Iterator itr = c.iterator();
while (itr.hasNext()){
System.out.println(itr.next());
}
c.remove("One");
Enumeration e = ht.elements();
while (e.hasMoreElements()){
System.out.println(e.nextElement());
}
}
}
</source>
Hashtable: entrySet()
<source lang="java">
/* {three=four, two=three, four=five, one=two} 4 three : four two : three four : five one : two three : four two : three four : five one : two
*/
import java.util.Enumeration; import java.util.Hashtable; import java.util.Iterator; import java.util.Map; import java.util.Set; public class MainClass {
public static void main(String args[]) throws Exception {
Hashtable hash = new Hashtable(89);
hash.put("one", "two");
hash.put("two", "three");
hash.put("three", "four");
hash.put("four", "five");
System.out.println(hash);
System.out.println(hash.size());
Enumeration e = hash.keys();
while (e.hasMoreElements()) {
String key = (String) e.nextElement();
System.out.println(key + " : " + hash.get(key));
}
Set set = hash.entrySet();
Iterator it = set.iterator();
while (it.hasNext()) {
Map.Entry entry = (Map.Entry) it.next();
System.out.println(entry.getKey() + " : " + entry.getValue());
}
}
}
</source>
Hashtable: get(E e)
<source lang="java">
/*
* Output:
Beijing is located in China
*/
import java.util.Hashtable; public class MainClass {
public static void main(String args[]) {
Hashtable ht = new Hashtable();
ht.put("Tokyo", "Japan");
ht.put("Beijing", "China");
ht.put("Bangkok", "Thailand");
String city = "Beijing";
String country = (String) ht.get(city);
if (country != null)
System.out.println(city + " is located in " + country);
else
System.out.println(city + " is not located in the hashtable");
}
}
</source>
Hashtable: isEmpty()
<source lang="java">
import java.util.Hashtable; public class Main {
public static void main(String[] s) {
Hashtable<String,String> table = new Hashtable<String,String>();
table.put("key1", "value1");
table.put("key2", "value2");
table.put("key3", "value3");
System.out.println(table.isEmpty());
System.out.println(table.size());
}
}
</source>
Hashtable: iterator()
<source lang="java">
/**
*Output: A: 4.34
E: -9.08 D: 9.22 C: 8.0 B: 3.22 A"s new balance: 1004.34
*/
import java.util.Hashtable; import java.util.Iterator; import java.util.Set; public class MainClass {
public static void main(String args[]) {
Hashtable<String, Double> balance = new Hashtable<String, Double>();
String str;
double bal;
balance.put("A", 4.34);
balance.put("B", 3.22);
balance.put("C", 8.00);
balance.put("D", 9.22);
balance.put("E", -9.08);
Set<String> set = balance.keySet();
Iterator<String> itr = set.iterator();
while (itr.hasNext()) {
str = itr.next();
System.out.println(str + ": " + balance.get(str));
}
System.out.println();
bal = balance.get("A");
balance.put("A", bal + 1000);
System.out.println("A"s new balance: " + balance.get("A"));
}
}
</source>
Hashtable: keys()
<source lang="java">
/*
* Output:
key = apple; value = red key = strawberry; value = red
*/
import java.util.Enumeration; import java.util.Hashtable; public class MainClass {
public static void main(String args[]) {
Hashtable hashtable = new Hashtable();
hashtable.put("apple", "red");
hashtable.put("strawberry", "red");
Enumeration e = hashtable.keys();
while(e.hasMoreElements()) {
Object k = e.nextElement();
Object v = hashtable.get(k);
System.out.println("key = " + k + "; value = " + v);
}
}
}
</source>
Hashtable: keySet()
<source lang="java">
/**
*Output: A: 4.34
E: -9.08 D: 9.22 C: 8.0 B: 3.22 A"s new balance: 1004.34
*/
import java.util.Hashtable; import java.util.Iterator; import java.util.Set; public class MainClass {
public static void main(String args[]) {
Hashtable<String, Double> balance = new Hashtable<String, Double>();
String str;
double bal;
balance.put("A", 4.34);
balance.put("B", 3.22);
balance.put("C", 8.00);
balance.put("D", 9.22);
balance.put("E", -9.08);
Set<String> set = balance.keySet();
Iterator<String> itr = set.iterator();
while (itr.hasNext()) {
str = itr.next();
System.out.println(str + ": " + balance.get(str));
}
System.out.println();
bal = balance.get("A");
balance.put("A", bal + 1000);
System.out.println("A"s new balance: " + balance.get("A"));
}
}
</source>
Hashtable: putAll(Map<K,V> t)
<source lang="java">
import java.util.Hashtable; public class Main{
public static void main(String[] s) {
Hashtable<String,String> table = new Hashtable<String,String>();
table.put("key1", "value1");
table.put("key2", "value2");
table.put("key3", "value3");
Hashtable<String,String> table2 = new Hashtable<String,String>();
table2.put("key4", "value4");
table2.put("key5", "value5");
table2.put("key6", "value6");
table2.putAll(table);
System.out.println(table2);
}
}
</source>
Hashtable: put(K key, V value)
<source lang="java">
/*
* Output: *
a: a b: 2.0 c: b d: 30
* * */
import java.util.Dictionary; import java.util.Hashtable; public class MainClass {
public static void main(String args[]) {
Hashtable ht = new Hashtable();
ht.put("a", "a");
ht.put("b", new Double(2));
ht.put("c", "b");
ht.put("d", new Integer(30));
show(ht);
}
static void show(Dictionary d) {
System.out.println("a: " + d.get("a"));
System.out.println("b: " + d.get("b"));
System.out.println("c: " + d.get("c"));
System.out.println("d: " + d.get("d"));
}
}
</source>
Hashtable: remove(Object key)
<source lang="java">
import java.util.Hashtable; public class Main{
public static void main(String[] s) {
Hashtable<String,String> table = new Hashtable<String,String>();
table.put("key1", "value1");
table.put("key2", "value2");
table.put("key3", "value3");
table.remove("key1");
System.out.println(table);
}
}
</source>
Hashtable: size()
<source lang="java">
import java.util.Hashtable; public class Main {
public static void main(String[] s) {
Hashtable<String,String> table = new Hashtable<String,String>();
table.put("key1", "value1");
table.put("key2", "value2");
table.put("key3", "value3");
System.out.println(table.isEmpty());
System.out.println(table.size());
}
}
</source>
Hashtable: values()
<source lang="java">
import java.util.Enumeration; import java.util.Hashtable; public class Main {
public static void main(String[] s) {
Hashtable<String,String> table = new Hashtable<String,String>();
table.put("key1", "value1");
table.put("key2", "value2");
table.put("key3", "value3");
Enumeration e = table.elements();
while (e.hasMoreElements()) {
String key = (String) e.nextElement();
System.out.println(key + " : " + table.get(key));
}
System.out.println(table.values());
}
}
</source>
new Hashtable()
<source lang="java">
/*
* Output: *
a: a b: 2.0 c: b d: 30
* * */
import java.util.Dictionary; import java.util.Hashtable; public class MainClass {
public static void main(String args[]) {
Hashtable ht = new Hashtable();
ht.put("a", "a");
ht.put("b", new Double(2));
ht.put("c", "b");
ht.put("d", new Integer(30));
show(ht);
}
static void show(Dictionary d) {
System.out.println("a: " + d.get("a"));
System.out.println("b: " + d.get("b"));
System.out.println("c: " + d.get("c"));
System.out.println("d: " + d.get("d"));
}
}
</source>
new Hashtable < K, V > ()
<source lang="java">
/**
*Output:
A: 3434.34
*/
import java.util.Enumeration; import java.util.Hashtable; public class MainClass {
public static void main(String args[]) {
Hashtable<String, Double> balance = new Hashtable<String, Double>();
Enumeration<String> names;
String str;
balance.put("A", 3434.34);
names = balance.keys();
while (names.hasMoreElements()) {
str = names.nextElement();
System.out.println(str + ": " + balance.get(str));
}
System.out.println();
}
}
</source>
