Java by API/java.util/Map

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implements Map

   <source lang="java">

/* You asked about Google. They are located in: null Key Adobe; Value Mountain View, CA Key IBM; Value White Plains, NY Key Learning Tree; Value Los Angeles, CA entrySet() returns 3 Map.Entry"s*/ import java.util.AbstractSet; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.Set; import java.util.TreeSet; public class MainClass { 

 public static void main(String[] argv) {
   Map map = new MyMap();
   map.put("Adobe", "Mountain View, CA");
   map.put("Learning Tree", "Los Angeles, CA");
   map.put("IBM", "White Plains, NY");
   String queryString = "Google";
   System.out.println("You asked about " + queryString + ".");
   String resultString = (String) map.get(queryString);
   System.out.println("They are located in: " + resultString);
   System.out.println();
   Iterator k = map.keySet().iterator();
   while (k.hasNext()) {
     String key = (String) k.next();
     System.out.println("Key " + key + "; Value " + (String) map.get(key));
   }
   Set es = map.entrySet();
   System.out.println("entrySet() returns " + es.size() + " Map.Entry"s");
 }

} class MyMap implements Map { 

 private ArrayList keys;
 private ArrayList values;
 public MyMap() {
   keys = new ArrayList();
   values = new ArrayList();
 }
 /** Return the number of mappings in this Map. */
 public int size() {
   return keys.size();
 }
 /** Return true if this map is empty. */
 public boolean isEmpty() {
   return size() == 0;
 }
 /** Return true if o is contained as a Key in this Map. */
 public boolean containsKey(Object o) {
   return keys.contains(o);
 }
 /** Return true if o is contained as a Value in this Map. */
 public boolean containsValue(Object o) {
   return keys.contains(o);
 }
 /** Get the object value corresponding to key k. */
 public Object get(Object k) {
   int i = keys.indexOf(k);
   if (i == -1)
     return null;
   return values.get(i);
 }
 /**
  * Put the given pair (k, v) into this map, by maintaining "keys" in sorted
  * order.
  */
 public Object put(Object k, Object v) {
   for (int i = 0; i < keys.size(); i++) {
     Object old = keys.get(i);
     /* Does the key already exist? */
     if (((Comparable) k).rupareTo(keys.get(i)) == 0) {
       keys.set(i, v);
       return old;
     }
     /*
      * Did we just go past where to put it? i.e., keep keys in sorted order.
      */
     if (((Comparable) k).rupareTo(keys.get(i)) == +1) {
       int where = i > 0 ? i - 1 : 0;
       keys.add(where, k);
       values.add(where, v);
       return null;
     }
   }
   // Else it goes at the end.
   keys.add(k);
   values.add(v);
   return null;
 }
 /** Put all the pairs from oldMap into this map */
 public void putAll(java.util.Map oldMap) {
   Iterator keysIter = oldMap.keySet().iterator();
   while (keysIter.hasNext()) {
     Object k = keysIter.next();
     Object v = oldMap.get(k);
     put(k, v);
   }
 }
 public Object remove(Object k) {
   int i = keys.indexOf(k);
   if (i == -1)
     return null;
   Object old = values.get(i);
   keys.remove(i);
   values.remove(i);
   return old;
 }
 public void clear() {
   keys.clear();
   values.clear();
 }
 public java.util.Set keySet() {
   return new TreeSet(keys);
 }
 public java.util.Collection values() {
   return values;
 }
 /**
  * The Map.Entry objects contained in the Set returned by entrySet().
  */
 private class MyMapEntry implements Map.Entry, Comparable {
   private Object key, value;
   MyMapEntry(Object k, Object v) {
     key = k;
     value = v;
   }
   public Object getKey() {
     return key;
   }
   public Object getValue() {
     return value;
   }
   public Object setValue(Object nv) {
     throw new UnsupportedOperationException("setValue");
   }
   public int compareTo(Object o2) {
     if (!(o2 instanceof MyMapEntry))
       throw new IllegalArgumentException("Huh? Not a MapEntry?");
     Object otherKey = ((MyMapEntry) o2).getKey();
     return ((Comparable) key).rupareTo((Comparable) otherKey);
   }
 }
 /** The set of Map.Entry objects returned from entrySet(). */
 private class MyMapSet extends AbstractSet {
   List list;
   MyMapSet(ArrayList al) {
     list = al;
   }
   public Iterator iterator() {
     return list.iterator();
   }
   public int size() {
     return list.size();
   }
 }
 /**
  * Returns a set view of the mappings contained in this Map. Each element in
  * the returned set is a Map.Entry. NOT guaranteed fully to implement the
  * contract of entrySet declared in java.util.Map.
  */
 public java.util.Set entrySet() {
   if (keys.size() != values.size())
     throw new IllegalStateException("InternalError: keys and values out of sync");
   ArrayList al = new ArrayList();
   for (int i = 0; i < keys.size(); i++) {
     al.add(new MyMapEntry(keys.get(i), values.get(i)));
   }
   return new MyMapSet(al);
 }

} 


 </source>



java.util.Map.Entry<K, V>

   <source lang="java">

import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Set; public class Main { 

 public static void main(String[] a) {
   Map<String,String> map = new HashMap<String,String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   Set set = map.entrySet();
   Iterator iter = set.iterator();
   while (iter.hasNext()) {
     Map.Entry entry = (Map.Entry) iter.next();
     System.out.println(entry.getKey() + " -- " + entry.getValue());
   }
 }

} 

 </source>



Map: clear()

   <source lang="java">

import java.util.HashMap; import java.util.Map; public class Main { 

 public static void main(String[] a) {
   Map<String,String> map = new HashMap<String,String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   map.clear();
   System.out.println(map);
 }

} 

 </source>



Map: containsKey(Object key)

   <source lang="java">

import java.util.HashMap; import java.util.Map; class Counter { 

 int i = 1;
 public String toString() {
   return Integer.toString(i);
 }

} public class Main { 

 public static void main(String[] args) {
   Map hm = new HashMap();
   for (int i = 0; i < 10; i++) {
     Integer r = new Integer(20);
     if (hm.containsKey(r))
       ((Counter) hm.get(r)).i++;
     else
       hm.put(r, new Counter());
   }
   System.out.println(hm);
 }

} 

 </source>



Map: containsValue(Object value)

   <source lang="java">

import java.util.HashMap; import java.util.Map; public class Main { 

 public static void main(String[] a) {
   Map<String,String> map = new HashMap<String,String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   System.out.println(map.containsKey("key1"));
   System.out.println(map.containsValue("value2"));
 }

} 

 </source>



Map.Entry: getKey()

   <source lang="java">

import java.util.Iterator; import java.util.Map; import java.util.Properties; public class Main { 

 public static void main(String[] a) {
   Properties props = System.getProperties();
   Iterator iter = props.entrySet().iterator();
   while (iter.hasNext()) {
     Map.Entry entry = (Map.Entry) iter.next();
     System.out.println(entry.getKey() + " -- " + entry.getValue());
   }
 }

} 

 </source>



Map.Entry: getValue()

   <source lang="java">

import java.util.HashMap; import java.util.Iterator; import java.util.Map; import java.util.Set; public class Main { 

 public static void main(String[] a) {
   Map<String,String> map = new HashMap<String,String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   Set set = map.entrySet();
   Iterator iter = set.iterator();
   while (iter.hasNext()) {
     Map.Entry entry = (Map.Entry) iter.next();
     System.out.println(entry.getKey() + " -- " + entry.getValue());
   }
 }

} 

 </source>



Map: equals(Object o)

   <source lang="java">

import java.util.HashMap; import java.util.Map; public class Main { 

 public static void main(String[] a) {
   Map<String,String> map = new HashMap<String,String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   Map<String,String> map2 = new HashMap<String,String>();
   map2.put("key2", "value2");
   map2.put("key1", "value1");
   map2.put("key3", "value3");
   System.out.println(map2.equals(map2));
 }

} 

 </source>



Map: get(Object key)

   <source lang="java">

import java.util.HashMap; import java.util.Map; public class Main{ 

 public static void main(String[] a) {
   Map<String,String> map = new HashMap<String,String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   System.out.println(map.get("key2"));
 }

} 

 </source>



Map: keySet()

   <source lang="java">

/* Key Adobe; Value Mountain View, CA Key IBM; Value White Plains, NY Key Learning Tree; Value Los Angeles, CA

  • /

import java.util.HashMap; import java.util.Iterator; import java.util.Map; public class MainClass { 

 public static void main(String[] argv) {
   Map map = new HashMap();
   map.put("Adobe", "Mountain View, CA");
   map.put("IBM", "White Plains, NY");
   map.put("Learning Tree", "Los Angeles, CA");
   Iterator k = map.keySet().iterator();
   while (k.hasNext()) {
     String key = (String) k.next();
     System.out.println("Key " + key + "; Value " + (String) map.get(key));
   }
 }

} 


 </source>



Map: putAll(Map<?, ?> m)

   <source lang="java">

import java.util.HashMap; import java.util.Map; public class Main { 

 public static void main(String[] a) {
   Map<String,String> map = new HashMap<String,String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   map.put(null, null);
   Map<String,String> map2 = new HashMap<String,String>();
   map2.put("key4", "value4");
   map2.put("key5", "value5");
   map2.put("key6", "value6");
   map.putAll(map2);
   System.out.println(map);
 }

} 

 </source>



Map: put(T key, T value)

   <source lang="java">

import java.util.HashMap; import java.util.Map; public class Main { 

 public static void main(String[] a) {
   Map<String, String> map = new HashMap<String, String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   System.out.println(map);
 }

} 

 </source>



Map: remove(Object key)

   <source lang="java">

import java.util.HashMap; import java.util.Map; public class Main { 

 public static void main(String[] a) {
   Map<String,String> map = new HashMap<String,String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   map.remove("key3");
   System.out.println(map);
 }

} 

 </source>



Map: size()

   <source lang="java">

import java.util.HashMap; import java.util.Map; public class Main{ 

 public static void main(String[] a) {
   Map<String,String> map = new HashMap<String,String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   System.out.println(map.size());
 }

} 

 </source>



Map: values()

   <source lang="java">

import java.util.Collection; import java.util.HashMap; import java.util.Iterator; import java.util.Map; public class Main { 

 public static void main(String[] a) {
   Map<String,String> map = new HashMap<String,String>();
   map.put("key1", "value1");
   map.put("key2", "value2");
   map.put("key3", "value3");
   Collection set = map.values();
   Iterator iter = set.iterator();
   while (iter.hasNext()) {
     System.out.println(iter.next());
   }
 }

} 

 </source>
Источник — «http://jexp.ru/index.php?title=Java_by_API/java.util/Map&oldid=73»