A simple telephone number database that uses a property list.

Here is a Java Program to A simple telephone number database that uses a property list.

import java.io.*;
import java.util.*;

class Phonebook {
  public static void main(String args[]) 
    throws IOException
  {
    Properties ht = new Properties();
    BufferedReader br =
      new BufferedReader(new InputStreamReader(System.in));
    String name, number;
    FileInputStream fin = null;
    boolean changed = false;

    // Try to open phonebook.dat file.
    try {
      fin = new FileInputStream("phonebook.dat");
    } catch(FileNotFoundException e) {
      // ignore missing file
    }

    /* If phonebook file already exists, 
       load existing telephone numbers. */
    try {
      if(fin != null) {
        ht.load(fin);
        fin.close();
      }
    } catch(IOException e) {
      System.out.println("Error reading file.");
    }

    // Let user enter new names and numbers.
    do {
      System.out.println("Enter new name" + 
                         " ('quit' to stop): ");
      name = br.readLine();
      if(name.equals("quit")) continue;

      System.out.println("Enter number: ");
      number = br.readLine();

      ht.put(name, number);
      changed = true;
    } while(!name.equals("quit"));

    // If phone book data has changed, save it.
    if(changed) {
      FileOutputStream fout = new FileOutputStream("phonebook.dat");

      ht.store(fout, "Telephone Book");    
      fout.close();
    }

    // Look up numbers given a name.
    do {
      System.out.println("Enter name to find" +
                         " ('quit' to quit): ");
      name = br.readLine();
      if(name.equals("quit")) continue;

      number = (String) ht.get(name);
      System.out.println(number);
    } while(!name.equals("quit"));
  }
}

Output of Above Java Program
sanjay
Enter number:
9977777516
Enter new name ('quit' to stop):
Hell
Enter number:
442312345348
Enter new name ('quit' to stop):
ASDF
Enter number:
4647511366489
Enter new name ('quit' to stop):
quit
Enter name to find ('quit' to quit):
sanjay
9977777516
Enter name to find ('quit' to quit):
asdf
null
Enter name to find ('quit' to quit):
ASDF
4647511366489
Enter name to find ('quit' to quit):
quit

[ Read More ]

Demonstrate a Property list

Here is a Java Program to Demonstrate a Property list.

import java.util.*;
 
class PropDemo {
  public static void main(String args[]) {
    Properties capitals = new Properties();
    Set states;
    String str;

    capitals.put("Illinois", "Springfield");
    capitals.put("Missouri", "Jefferson City");
    capitals.put("Washington", "Olympia");
    capitals.put("California", "Sacramento");
    capitals.put("Indiana", "Indianapolis");

    // Show all states and capitals in hashtable.
    states = capitals.keySet(); // get set-view of keys
    Iterator itr = states.iterator();

    while(itr.hasNext()) {
      str = (String) itr.next();
      System.out.println("The capital of " +
                         str + " is " +
                         capitals.getProperty(str)
                         + ".");
    }

    System.out.println();

    // look for state not in list -- specify default
    str = capitals.getProperty("Florida", "Not Found");
    System.out.println("The capital of Florida is "
                       + str + ".");
  }
}

Output of Above Java Program
The capital of Missouri is Jefferson City.
The capital of Illinois is Springfield.
The capital of Indiana is Indianapolis.
The capital of California is Sacramento.
The capital of Washington is Olympia.

The capital of Florida is Not Found.

[ Read More ]