Java Hash Table Pro

Iterate through keys of Java Hash table

import java.util.Hashtable;

import java.util.Enumeration;

public class IterateThroughKeysOfHashtableExample

{

public static void main(String[] args)

{

Hashtable ht = new Hashtable();

ht.put("1","One");

ht.put("2","Two");

ht.put("3","Three");

Enumeration e = ht.keys();

while(e.hasMoreElements())

System.out.println(e.nextElement());

    }

}

Iterate through values of Java Hash table

import java.util.Hashtable;

import java.util.Enumeration; 

public class IterateValuesOfHashtableExample

{

public static void main(String[] args)

{

Hashtable ht = new Hashtable();

ht.put("1","One");

ht.put("2","Two");

ht.put("3","Three");

Enumeration e = ht.elements();

while(e.hasMoreElements())

System.out.println(e.nextElement());

  }

}

Get All Entries From Zip File

import java.io.IOException;

import java.util.Enumeration;

import java.util.zip.ZipEntry;

import java.util.zip.ZipFile; 

public class GetAllEntries

{

 public static void main(String args[])

{

try

{

ZipFile zipFile = new ZipFile("c:/FileIO/WebFiles.zip");Enumeration e = zipFile.entries();

zipFile.close();

}

catch(IOException ioe)

{

System.out.println("Error opening zip file" + ioe);

    }

  }

}

Check if a particular key exists in Java Hash Map

import java.util.HashMap;  

public class CheckKeyOfHashMapExample

{

public static void main(String[] args)

{

HashMap hMap = new HashMap();

  

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);

    }

}

Check if a particular value exists in Java Hash Map

import java.util.HashMap; 

public class CheckValueOfHashMapExample

{

public static void main(String[] args)

{

HashMap hMap = new HashMap();

hMap.put("1","One");

hMap.put("2","Two");

hMap.put("3","Three");

boolean blnExists = hMap.containsValue("Two");

System.out.println("Two exists in HashMap ? : " + blnExists);

   }

}

Get Set view of Keys from Java Hash Map

import java.util.Iterator;

import java.util.HashMap;

import java.util.Set; 

public class GetSetViewOfKeysFromHashMapExample

{

public static void main(String[] args)

{

HashMap hMap = new HashMap();

hMap.put("1","One");

hMap.put("2","Two");

hMap.put("3","Three");

Set st = hMap.keySet();

System.out.println("Set created from HashMap Keys contains :");

Iterator itr = st.iterator();

while(itr.hasNext())

System.out.println(itr.next());

st.remove("2");

boolean blnExists = hMap.containsKey("2");

System.out.println("Does HashMap contain 2 ? " + blnExists);

   }

}

Get Size of Java Hash Map

import java.util.HashMap; 

public class GetSizeOfHashMapExample

{

public static void main(String[] args)

{

HashMap hMap = new HashMap();

System.out.println("Size of HashMap : " + hMap.size());

hMap.put("1","One");

hMap.put("2","Two");

hMap.put("3","Three");

System.out.println("Size of HashMap after addition : " + hMap.size());

Object obj = hMap.remove("2");

System.out.println("Size of HashMap after removal : " + hMap.size());

   }

}

Iterate through the values of Java Hash Map

import java.util.Collection;

import java.util.HashMap;

import java.util.Iterator;

public class IterateValuesOfHashMapExample

{

public static void main(String[] args)

{

HashMap hMap = new HashMap();

hMap.put("1","One");

hMap.put("2","Two");

hMap.put("3","Three");

Collection c = hMap.values();  Iterator itr = c.iterator();

while(itr.hasNext())

System.out.println(itr.next());

   }

}

Remove all values from Java Hash Map

import java.util.HashMap; 

public class EmptyHashMapExample

{

 public static void main(String[] args)

{

HashMap hMap = new HashMap();

hMap.put("1","One");

hMap.put("2","Two");

hMap.put("3","Three");

hMap.clear();

System.out.println("Total key value pairs in HashMap are : " + hMap.size());

  }

}