Java by API/java.util/HashMap

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HashMap: clear()

  
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);
  }
}





HashMap: clone()

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





HashMap: containsKey(Object key)

 
import java.util.HashMap;
public class Main {
  public static void main(String[] args) {
    HashMap<String, String> hMap = new HashMap<String, String>();
    hMap.put("1", "One");
    hMap.put("2", "Two");
    hMap.put("3", "Three");
    boolean blnExists = hMap.containsKey("3");
    System.out.println("3 exists in HashMap ? : " + blnExists);
  }
}





HashMap: containsValue(Object value)

  
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"));
  }
}





HashMap: entrySet()

  
/**
 *Output: 
D: 99.22
A: 3434.34
C: 1378.0
B: 123.22
E: -19.08
B"s new balance: 1123.22
 */
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class MainClass {
  public static void main(String args[]) {
    HashMap<String, Double> hm = new HashMap<String, Double>();
    hm.put("A", new Double(3434.34));
    hm.put("B", new Double(123.22));
    hm.put("C", new Double(1378.00));
    hm.put("D", new Double(99.22));
    hm.put("E", new Double(-19.08));
    Set<Map.Entry<String, Double>> set = hm.entrySet();
    for (Map.Entry<String, Double> me : set) {
      System.out.print(me.getKey() + ": ");
      System.out.println(me.getValue());
    }
    System.out.println();
    double balance = hm.get("B");
    hm.put("B", balance + 1000);
    System.out.println("B"s new balance: " + hm.get("B"));
  }
}





HashMap: get(E o)

  
/**
 *Output: 
D: 99.22
A: 3434.34
C: 1378.0
B: 123.22
E: -19.08
B"s new balance: 1123.22
 */
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class MainClass {
  public static void main(String args[]) {
    HashMap<String, Double> hm = new HashMap<String, Double>();
    hm.put("A", new Double(3434.34));
    hm.put("B", new Double(123.22));
    hm.put("C", new Double(1378.00));
    hm.put("D", new Double(99.22));
    hm.put("E", new Double(-19.08));
    Set<Map.Entry<String, Double>> set = hm.entrySet();
    for (Map.Entry<String, Double> me : set) {
      System.out.print(me.getKey() + ": ");
      System.out.println(me.getValue());
    }
    System.out.println();
    double balance = hm.get("B");
    hm.put("B", balance + 1000);
    System.out.println("B"s new balance: " + hm.get("B"));
  }
}





HashMap: keySet()

 

import java.util.HashMap;
import java.util.Iterator;
import java.util.Set;
public class Main {
  public static void main(String[] args) {
    HashMap<String, String> hMap = new HashMap<String, String>();
    hMap.put("1", "One");
    hMap.put("2", "Two");
    hMap.put("3", "Three");
    Set st = hMap.keySet();
    Iterator itr = st.iterator();
    while (itr.hasNext())
      System.out.println(itr.next());
    // remove 2 from Set
    st.remove("2");
    System.out.println(hMap.containsKey("2"));
  }
}





HashMap: putAll(Map<?, ?> m)

  
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);
  }
}





HashMap: put(E o, E o1)

  
/**
 *Output: 
D: 99.22
A: 3434.34
C: 1378.0
B: 123.22
E: -19.08
B"s new balance: 1123.22
 */
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class MainClass {
  public static void main(String args[]) {
    HashMap<String, Double> hm = new HashMap<String, Double>();
    hm.put("A", new Double(3434.34));
    hm.put("B", new Double(123.22));
    hm.put("C", new Double(1378.00));
    hm.put("D", new Double(99.22));
    hm.put("E", new Double(-19.08));
    Set<Map.Entry<String, Double>> set = hm.entrySet();
    for (Map.Entry<String, Double> me : set) {
      System.out.print(me.getKey() + ": ");
      System.out.println(me.getValue());
    }
    System.out.println();
    double balance = hm.get("B");
    hm.put("B", balance + 1000);
    System.out.println("B"s new balance: " + hm.get("B"));
  }
}





HashMap: remove(Object key)

  
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);
  }
}





HashMap: size()

  
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());
  }
}





HashMap: values()

  
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());
    }
  }
}





new HashMap < K, V > ()

  
/**
 *Output: 
D: 99.22
A: 3434.34
C: 1378.0
B: 123.22
E: -19.08
B"s new balance: 1123.22
 */
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class MainClass {
  public static void main(String args[]) {
    HashMap<String, Double> hm = new HashMap<String, Double>();
    hm.put("A", new Double(3434.34));
    hm.put("B", new Double(123.22));
    hm.put("C", new Double(1378.00));
    hm.put("D", new Double(99.22));
    hm.put("E", new Double(-19.08));
    Set<Map.Entry<String, Double>> set = hm.entrySet();
    for (Map.Entry<String, Double> me : set) {
      System.out.print(me.getKey() + ": ");
      System.out.println(me.getValue());
    }
    System.out.println();
    double balance = hm.get("B");
    hm.put("B", balance + 1000);
    System.out.println("B"s new balance: " + hm.get("B"));
  }
}


Источник — «http://jexp.ru/index.php?title=Java_by_API/java.util/HashMap&oldid=123»