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.

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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