import java.io.ByteArrayOutputStream;
import java.io.FileInputStream; 
import java.io.FileNotFoundException; 
import java.io.IOException; 
import java.io.InputStream; 
import org.apache.commons.io.IOUtils; 
public class InputStreamToByteArray { 
   public static void main(String args[]) throws FileNotFoundException, IOException 
   { //Converting InputStream to byte array using apche commons IO library 
     int length = toByteArrayUsingCommons(new FileInputStream("C:/temp/abc.txt")).length; 
  System.out.println("Length of byte array created from InputStream in Java using IOUtils : " + length); 
  
  //Converting InputStream to Byte arrray using Java code 
  length = toByteArrayUsingJava(new FileInputStream("C:/temp/abc.txt")).length; 
  System.out.println("Length of Byte array created from FileInputStream in Java : " + length); 
   } 
   /* * Converts InputStream to ByteArray in Java using Apache commons IOUtils class */ 
   
   public static byte[] toByteArrayUsingCommons(InputStream is) throws IOException{ 
     return IOUtils.toByteArray(is); 
  } 
  
  /* * Read bytes from inputStream and writes to OutputStream, later converts * OutputStream to byte array in Java. */ 
  public static byte[] toByteArrayUsingJava(InputStream is) throws IOException{
      ByteArrayOutputStream baos = new ByteArrayOutputStream(); 
    int reads = is.read(); 
    while(reads != -1)
    { 
      baos.write(reads); 
   reads = is.read(); 
    }
    return baos.toByteArray(); 
    } 
}

 Output: 
 Length of byte array created from InputStream in Java using IOUtils : 27
 Length of Byte array created from FileInputStream in Java : 27 

Calendar cal = Calendar.getInstance();
   cal.setTime(date);
   cal.set(Calendar.HOUR_OF_DAY, 0);
   cal.set(Calendar.MINUTE, 0);    
   cal.set(Calendar.SECOND, 0);    
   cal.set(Calendar.MILLISECOND, 0);    
          
   return cal.getTime();

public static void main( String[] args ) 
    {
     try{
 
      SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");
         Date date1 = sdf.parse("2009-12-31");
         Date date2 = sdf.parse("2010-01-31");
 
         System.out.println(sdf.format(date1));
         System.out.println(sdf.format(date2));
 
         if(date1.compareTo(date2)>0){
          System.out.println("Date1 is after Date2");
         }else if(date1.compareTo(date2)<0){
          System.out.println("Date1 is before Date2");
         }else if(date1.compareTo(date2)==0){
          System.out.println("Date1 is equal to Date2");
         }else{
          System.out.println("How to get here?");
         }
 
     }catch(ParseException ex){
      ex.printStackTrace();
     }
    }

//String to Date Conversion
 stringDate = "10-04-2013";

 public Date stringToDate(String stringDate)
 {
  Date date = null;
  try {
   SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
   date = sdf.parse(stringDate);
   System.out.println(date);
   return date;
  } catch (ParseException e) {
   e.printStackTrace();
   return date;
  }
 }

import java.sql.Timestamp;

//Timestamp to Date Conversion
 public Date timeStampToDate(Timestamp timestamp)
 {
  Date date = null;
  try
  {
    date = new Date(timestamp.getTime());
    return date;
  }catch (Exception e) {
   e.printStackTrace();
   return date;
  }
 }

<%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

<display:column sortable="true" title="Grand Total">
        <c:if test="${data.zone != 'GRAND TOTAL'}">      
            <html:link action="/exceptionScoreCardGrandReport.do?zone=${data.zone}">
                <b>${data.grandTotal}</b>
            </html:link>
        </c:if>
    </display:column>  

import java.io.IOException;

import org.apache.log4j.Logger;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;

/*
 * Java program to convert JSON String into Java object using Jackson library.
 * Jackson is very easy to use and require just two lines of code to create a Java object
 * from JSON String format.
 *
 * @author Harit Rajput
 */
public class JsonToJavaConverter {

        private static Logger logger = Logger.getLogger(JsonToJavaConverter.class);
      
      
        public static void main(String args[]) throws JsonParseException
                                                    , JsonMappingException, IOException{

                JsonToJavaConverter converter = new JsonToJavaConverter();
              
                String json = "{\n" +
                "    \"name\": \"Harit\",\n" +
                "    \"surname\": \"Kumar\",\n" +
                "    \"phone\": 9832734651}";
              
                //converting JSON String to Java object
                converter.fromJson(json);
        }
      
      
        public Object fromJson(String json) throws JsonParseException
                                                   , JsonMappingException, IOException{
                User obj = new ObjectMapper().readValue(json, User.class);
                logger.info("Java Object created from JSON String ");
                logger.info("JSON String : " + json);
                logger.info("Java Object : " + obj);
              
                return obj;
        }
      
public static class User{
                private String name;
                private String surname;
                private long phone;
              
                public String getName() {return name;}
                public void setName(String name) {this.name = name;}

                public String getSurname() {return surname;}
                public void setSurname(String surname) {this.surname = surname;}

                public long getPhone() {return phone;}
                public void setPhone(long phone) {this.phone = phone;}

                @Override
                public String toString() {
                        return "User [name=" + name + ", surname=" + surname + ", phone="
                                        + phone + "]";
                }
              
               
        }
}

2013-01-07 01:15:05,287 0    [main] INFO  JsonToJavaConverter  - Java Object created from JSON String
2013-01-07 01:15:05,287 0    [main] INFO  JsonToJavaConverter  - JSON String : {
    "name": "Harit",
    "surname": "Kumar",
    "phone": 9787878788}
2013-01-07 01:15:05,287 0    [main] INFO  JsonToJavaConverter  - Java Object : User [name=Harit, surname=Kumar, phone=9787878788]

public class EnumTest {

    private enum LOAN {

        HOME_LOAN {
            @Override
            public String toString() {
                return "Always look for cheaper Home loan";
            }
        },
        AUTO_LOAN {
            @Override
            public String toString() {
                return "Cheaper Auto Loan is better";
            }
        },
        PEROSNAL_LOAN{
            @Override
            public String toString() {
                return "Personal loan is not cheaper any more";
            }
        }
    }

    public static void main(String[] args) {
     
        //Exmaple of String to Enum in Java
        LOAN homeLoan = LOAN.valueOf("HOME_LOAN");
        System.out.println(homeLoan);
        LOAN autoLoan = LOAN.valueOf("AUTO_LOAN");
        System.out.println(autoLoan);
        LOAN personalLoan = LOAN.valueOf("PEROSNAL_LOAN");
        System.out.println(personalLoan);
     
    }

Output:
Always look for cheaper Home loan
Cheaper Auto Loan is better
Personal loan is not cheaper any more

public static void main(String[] args) {
     
        //Exmaple of Enum to String in Java
        String homeLoan = LOAN.HOME_LOAN.name();
        System.out.println(homeLoan);
        String autoLoan = LOAN.AUTO_LOAN.name();
        System.out.println(autoLoan);
        String personalLoan = LOAN.PERSONAL_LOAN.name();
        System.out.println(personalLoan);
      
    
     
    }

Output:
HOME_LOAN
AUTO_LOAN
PERSONAL_LOAN

public class StringComparisonExample {

    public static void main(String args[]) {

        String tv = "Bravia";
        String television = "Bravia";

        // String compare example using equals
        if (tv.equals(television)) {
            System.out.println("Both tv and television contains same letters and equal by equals method of String");
        }

        // String compare example in java using compareTo
        if (tv.compareTo(television) == 0) {
            System.out.println("Both tv and television are equal using compareTo method of String");
        }

        television = "BRAVIA";

        // Java String comparison example using equalsIgnoreCase
        if (tv.equalsIgnoreCase(television)) {
            System.out.println("tv and television are equal by equalsIgnoreCase method of String");
        }

        // String comparison example in java using CompareToIgnoreCase
        if (tv.compareToIgnoreCase(television) == 0) {
            System.out.println("tv and television are same by compareToIgnoreCase of String");
        }

        String sony = "Sony";
        String samsung = "Samsung";

        // lexicographical comparison of String in Java with ComapreTo
        if (sony.compareTo(samsung) > 0) {
            System.out.println("Sony comes after Samsung in lexicographical order");
        } else if (sony.compareTo(samsung) < 0) {
            System.out.println("Sony comes before Samsung in lexicographical order");
        }
    }

}

Output:
Both tv and television contains same letters and equal by equals method of String
Both tv and television are equal using compareTo method of String
tv and television are equal by equalsIgnoreCase method of String
tv and television are same by compareToIgnoreCase of String
Sony comes after Samsung in lexicographical order

public final boolean equals(Object other)
{ 
    return this==other; 
}

private enum Shape
{
   RECTANGLE, SQUARE, CIRCLE, TRIANGLE; 
} 

private enum Status
{ 
  ON, OFF; 
} 
Shape unknown = null; 
Shape circle = Shape.CIRCLE; 
boolean result = unknown == circle; //return false 
result = unknown.equals(circle); //throws NullPointerException

public final int compareTo(E o) 
{ 
  Enum other = (Enum)o; 
  Enum self = this; 
  if (self.getClass() != other.getClass() && // optimization 
      self.getDeclaringClass() != other.getDeclaringClass()) 
   throw new ClassCastException(); 
  return self.ordinal - other.ordinal; 
}

/**
  * Converting Second In to MM:SS time
  * @param seconds
  * @author harit Kumar
  * @return time MM:SS
  */
 public String secToTime(int seconds)
 {
  String time= "";
  if(seconds > 59)
  {
   int minutes = seconds/60;
   int sec = seconds%60;
   time = minutes+":"+sec;
  }
  else 
  {
   time = "00:"+seconds;
  }
  return time;
 }

public class StackTraceExample {

 public static void main(String args[]) 
   { 
  //calling a method to print stack trace further down
  first(); 
 } 
 public static void first()
 { 
  second();
  } 
 
 private static void second() 
 { 
  third();
 }
 
 private static void third() 
 { 
  //If you want to print stack trace on console than use dumpStack() method 
  System.err.println("Stack trace of current thread using dumpStack() method"); 
  Thread.currentThread().dumpStack(); 
  
  //This is another way to print stack trace from current method 
  System.err.println("Printing stack trace using printStackTrace() method of Throwable "); 
  new Throwable().printStackTrace(); 
  
  //If you want stack trace as StackTraceElement in program itself than //use getStackTrace() method of Thread class 
  StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace(); 
  
  //Once you get StackTraceElement you can also print it to console 
  System.err.println("displaying Stack trace from StackTraceElement in Java"); 
  for(StackTraceElement st : stackTrace)
  {
   System.err.println(st);
  }

  }
}

Stack trace of current thread using dumpStack() method
java.lang.Exception: Stack trace
 at java.lang.Thread.dumpStack(Thread.java:1206)
 at StackTraceExample.third(StackTraceExample.java:22)
 at StackTraceExample.second(StackTraceExample.java:15)
 at StackTraceExample.first(StackTraceExample.java:10)
 at StackTraceExample.main(StackTraceExample.java:6)
Printing stack trace using printStackTrace() method of Throwable 
java.lang.Throwable
 at StackTraceExample.third(StackTraceExample.java:26)
 at StackTraceExample.second(StackTraceExample.java:15)
 at StackTraceExample.first(StackTraceExample.java:10)
 at StackTraceExample.main(StackTraceExample.java:6)
displaying Stack trace from StackTraceElement in Java
java.lang.Thread.getStackTrace(Thread.java:1436)
StackTraceExample.third(StackTraceExample.java:29)
StackTraceExample.second(StackTraceExample.java:15)
StackTraceExample.first(StackTraceExample.java:10)
StackTraceExample.main(StackTraceExample.java:6)

import java.text.SimpleDateFormat; 
import java.util.Calendar; 
import java.util.Date;
/**
 *  @author Harit 
 *  */ 

public class IncrementDecrementDate 
{ 
 public static void main(String args[]) 
 { 
  //Using Calendar to increment and decrement days from date in Java 
  Date today = new Date(); 
  System.out.println("Today is " + toddMMyy(today)); 
  Calendar cal = Calendar.getInstance(); 
  
  //adding one day to current date 
  cal.add(Calendar.DAY_OF_MONTH, 1); 
  Date tommrrow = cal.getTime(); 
  System.out.println("Tomorrow will be " + toddMMyy(tommrrow));
  
  //substracting two day from date in Java 
  cal.add(Calendar.DAY_OF_MONTH, -2); 
  Date yesterday = cal.getTime(); 
  System.out.println("Yesterday was " + toddMMyy(cal.getTime())); 
  
  
 } 
 
 public static String toddMMyy(Date day)
 { 
  SimpleDateFormat formatter = new SimpleDateFormat("dd-MM-yy"); 
  String date = formatter.format(day);
  return date; 
 } 
 
 }

JSON:

{
"recentVideosList":[{"tags":null,"followerId":null,"videoId":"hLta6iJGtH8=","videoViewCount":"0","title":"twitter2","videoURL":"https://s3.amazonaws.com/youbusk/63/1364047039_011760.mov","userFollowingThisVideo":"No","videosByThisUser":"5","videoTimer":"6","videoUploadDateTime":"2013-03-25 07:41:49.0","isAlreadyFlagged":"N","uploadedByCountryId":"96","uploadedByUserId":"xHj2V0LLsfE=","thumbnailURL":"https://s3.amazonaws.com/youbusk/63/1364047039_011760.png","aboutUploadedBy":"ddddddddretreyreyrtyrt","tips":"0","uploadedBy":"naveen140990","abuseCount":"0","videoShareCount":"0","isAlreadyLiked":"NO"}],

"challengeOfTheDayList":[{"notificationId":"1","notificationDescription":"This is the first notification of videos."}],

"videoOfTheDayList":[{"tags":null,"followerId":null,"videoId":"jFB425S0Rv0=","videoViewCount":"9","title":"shr","videoURL":"https://s3.amazonaws.com/youbusk/2/1360314335_608470.mov","userFollowingThisVideo":"No","videosByThisUser":"6","videoTimer":"16","videoUploadDateTime":"2013-02-08 14:32:00.0","isAlreadyFlagged":"Y","uploadedByCountryId":"241","uploadedByUserId":"jFB425S0Rv0=","thumbnailURL":"https://s3.amazonaws.com/youbusk/2/1360314335_608470.png","aboutUploadedBy":"","tips":"14","uploadedBy":"gaurav11","abuseCount":"3","videoShareCount":"0","isAlreadyLiked":"YES"}],

"totalDataRequested":"2",
"totalDataSent":"2",
"responseCode":"4060",
"responseDescription":"Home service sent successfully."
}

JsonToObject.java

package com;

import java.io.IOException;

import org.codehaus.jackson.JsonFactory;
import org.codehaus.jackson.JsonParseException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;


public class JsonToObject{

 public CustomBean jsonConvertor(String jsonString)
 {
  JsonFactory factory = new JsonFactory();
  ObjectMapper mapper = new ObjectMapper(factory);
  try 
  {
   CustomBean customBean = mapper.readValue(jsonString, CustomBean.class);
   
   return customBean;
  } catch (JsonParseException e) {
   e.printStackTrace();
  } catch (JsonMappingException e) {
   e.printStackTrace();
  } catch (IOException e) {
   e.printStackTrace();
  }
   return new CustomBean();
 }
}

CustomBean

package com;

import java.util.List;

public class CustomBean {

 private List recentVideosList;
 private List videoOfTheDayList;
 private List challengeOfTheDayList;
 private String totalDataRequested;
 private String totalDataSent;
 private String responseCode;
 private String responseDescription;
 
 public List getRecentVideosList() {
  return recentVideosList;
 }
 public void setRecentVideosList(List recentVideosList) {
  this.recentVideosList = recentVideosList;
 }
 public List getVideoOfTheDayList() {
  return videoOfTheDayList;
 }
 public void setVideoOfTheDayList(List videoOfTheDayList) {
  this.videoOfTheDayList = videoOfTheDayList;
 }
 public List getChallengeOfTheDayList() {
  return challengeOfTheDayList;
 }
 public void setChallengeOfTheDayList(
   List challengeOfTheDayList) {
  this.challengeOfTheDayList = challengeOfTheDayList;
 }
 public String getTotalDataRequested() {
  return totalDataRequested;
 }
 public void setTotalDataRequested(String totalDataRequested) {
  this.totalDataRequested = totalDataRequested;
 }
 public String getTotalDataSent() {
  return totalDataSent;
 }
 public void setTotalDataSent(String totalDataSent) {
  this.totalDataSent = totalDataSent;
 }
 public String getResponseCode() {
  return responseCode;
 }
 public void setResponseCode(String responseCode) {
  this.responseCode = responseCode;
 }
 public String getResponseDescription() {
  return responseDescription;
 }
 public void setResponseDescription(String responseDescription) {
  this.responseDescription = responseDescription;
 }
 
}

public final class Contacts {

    private final String name;
    private final String mobile;

    public Contacts(String name, String mobile) {
        this.name = name;
        this.mobile = mobile;
    }
  
    public String getName(){
        return name;
    }
  
    public String getMobile(){
        return mobile;
    }
}

public final class ImmutableReminder{
    private final Date remindingDate;
  
    public ImmutableReminder (Date remindingDate) {
        if(remindingDate.getTime() < System.currentTimeMillis()){
            throw new IllegalArgumentException("Can not set reminder” +
                        “ for past time: " + remindingDate);
        }
        this.remindingDate = new Date(remindingDate.getTime());
    }
  
    public Date getRemindingDate() {
        return (Date) remindingDate.clone();
    }
}

Here is what the different pieces of System.out.println() actually look like: 

//the System class belongs to java.lang package 
class System { 
public static final PrintStream out; 
//... 
} 

//the Prinstream class belongs to java.io package 
class PrintStream{ 
public void println(); 
//... 
} 

char ch = 'U';
String charToString = Character.toString(ch);

char ch = 'U';
String str = "" + ch;

char ch = 'U';
String fromChar = new String(new char[]{ch});

4: using String.valueOf()

char ch = 'U';
String valueOfchar = String.valueOf(ch);

public class CharToStringExample {

       public static void main(String args[]) {
              char ch = 'U';

              // char to string using Character class
              String charToString = Character.toString(ch);
              System.out.println("Converting Char to String using Character class: " + charToString);

              // char to String using String concatenation
              String str = "" + ch;
              System.out.println("Converting Char to String using String concatenation: " + str);

              // char to String using anonymous array
              String fromChar = new String(new char[] { ch });
              System.out.println("Converting Char to String using anonymous array: " + fromChar);

              // char to String using String valueOf
              String valueOfchar = String.valueOf(ch);
              System.out.println("Converting Char to String using String valueOf: " + valueOfchar);

       }

}

Output:
Converting Char to String using Character class: U
Converting Char to String using String concatenation: U
Converting Char to String using anonymous array: U
Converting Char to String using String valueOf: U

•  String is immutable in Java.Immutability offers lot of benefit to the String class e.g. his hashcode value can be cached which makes it a faster hashmap key and one of the reason why String is a popular key in HashMap. Because String is final it can be safely shared between multiple threads  without any extra synchronization. 
• when we represent string in double quotes like "abcd" they are referred as String literal and String literals are created in String pools. When you compare two String literals using equality operator "==" it returns true because they are actually same instance of String. Anyway comparing object with equality operator is bad practice in Java and you should always use equals method to check equality.
• "+" operator is overloaded for String and used to concatenated two string. Internally "+" operation is implemented using either StringBuffer or StringBuilder.
• Strings are backed up by character Array and represented in UTF-16 format. By the way this behavior can cause memory leak in String because same character array is shared between source String and SubString which can prevent source String from being garbage collected.
• String class overrides equals() and hashcode() method and two Strings are considered to be equal if they contain exactly same character in same order and in same case. If you want ignore case comparison of two strings consider using equalsIgnoreCase() method.
• toString() method provides String representation of any object and its declared in Object class and its recommended for other class to implement this and provide String representation.
• In Java you can create String from char array, byte array, another string, from StringBuffer or from StringBuilder. Java String class provides constructor for all of these.

public class Counter{
private static int count = 0;

public static synchronized int getCount(){
  return count;
}

public synchoronized setCount(int count){
   this.count = count;
}

}

public class Singleton{
private static volatile Singleton _instance;

public static Singleton getInstance(){

   if(_instance == null){
            synchronized(Singleton.class){
              if(_instance == null)
              _instance = new Singleton();
            }

   }
   return _instance;

}

1. Synchronized keyword in Java is used to provide mutual exclusive access of a shared resource with multiple threads in Java. Synchronization in java guarantees that no two threads can execute a synchronized method which requires same lock simultaneously or concurrently.
2. You can use java synchronized keyword only on synchronized method or synchronized block.
3. When ever a thread enters into java synchronized method or block it acquires a lock and whenever it leaves java synchronized method or block it releases the lock. Lock is released even if thread leaves synchronized method after completion or due to any Error or Exception.
4. Java Thread acquires an object level lock when it enters into an instance synchronized java method and acquires a class level lock when it enters into static synchronized java method.
5. java synchronized keyword is re-entrant in nature it means if a java synchronized method calls another synchronized method which requires same lock then current thread which is holding lock can enter into that method without acquiring lock.
6. Java Synchronization will throw NullPointerException if object used in java synchronized block is null e.g. synchronized (myInstance) will throws NullPointerException if myInstance is null.
7. One Major disadvantage of java synchronized keyword is that it doesn't allow concurrent read which you can implement using java.util.concurrent.locks.ReentrantLock.
8. One limitation of java synchronized keyword is that it can only be used to control access of shared object within the same JVM. If you have more than one JVM and need to synchronized access to a shared file system or database, the java synchronized keyword is not at all sufficient. You need to implement a kind of global lock for that.
10. Java synchronized keyword incurs performance cost. Synchronized method in Java is very slow and can degrade performance. So use synchronization in java when it absolutely requires and consider using java synchronized block for synchronizing critical section only.
11. Its possible that both static synchronized and non static synchronized method can run simultaneously or concurrently because they lock on different object.
12. Java synchronized code could result in deadlock or starvation while accessing by multiple thread if synchronization is not implemented correctly.
13. You cannot apply java synchronized keyword with variables and can not use java volatile keyword with method.
14. java synchronized keyword also synchronizes memory. In fact java synchronized synchronizes the whole of thread memory with main memory.
15. Do not synchronize on non final field on synchronized block in Java. because reference of non final field may change any time and then different thread might synchronizing on different objects i.e. no synchronization at all. example of synchronizing on non final field :
    private String lock = new String("lock");

synchronized(lock){
System.out.println("locking on :"  + lock);
}

private static final String LOCK = "lock";   //not recommended
private static final Object OBJ_LOCK = new Object(); //better

public void process() {
   synchronized(LOCK) {
      ........
   }
}

1. Main difference between wait and sleep is that wait() method release the acquired lock when thread is waiting while Thread.sleep() method keeps the lock or monitor even if thread is waiting.
2. wait method in java should be called from synchronized method or block while there is no such requirement for sleep() method.
3. Thread.sleep() method is a static method and applies on current thread, while wait() is an instance specific method and only got wake up if some other thread calls notify method on same object.
4. in case of sleep, sleeping thread immediately goes to Runnable state after waking up while in case of wait, waiting thread first acquires the lock and then goes into Runnable state.
5. wait is called on Object while sleep is called on Thread.
6. wait is called from synchronized context only while sleep can be called without synchronized block.
7. Thread.sleep() method is a static method and always puts current thread on sleep.

/*
 * Example of Thread Sleep method in Java
 */
public class SleepTest {
      
       public static void main(String... args){
              System.out.println(Thread.currentThread().getName() + " is going to sleep for 1 Second");
              try {
                     Thread.currentThread().sleep(1000);
              } catch (InterruptedException e) {
                     // TODO Auto-generated catch block
                     e.printStackTrace();
              }
              System.out.println("Main Thread is woken now");
       }

}

Output:
main is going to sleep for 1 Second
Main Thread is woken now

package defaultt;

public class Customer {
int amount=0;
int flag=0;
public synchronized int withdraw(int amount){
 System.out.println(Thread.currentThread().getName()+" is going to withdraw");
 
       if(flag==0){
        try{
  System.out.println("waiting....");
  wait();
 }catch(Exception e){}
 }
       
 this.amount-=amount;
 System.out.println("withdraw completed");
 return amount;
}

public synchronized void deposit(int amount){
 System.out.println(Thread.currentThread().getName()+" is going to  deposit");
 this.amount+=amount;
 
 notifyAll();
 System.out.println("deposit completed");
        flag=1;
 }


}

package defaultt;

public class Test{
public static void main(String[] args) {
 final Customer c=new Customer();
 
 Thread t1=new Thread(){
  public void run(){
   c.withdraw(5000);
   System.out.println("After withdraw amount is"+c.amount);
  }
 };
 
 Thread t2=new Thread(){
  public void run(){
   c.deposit(9000);
   System.out.println("After deposit amount is "+c.amount);
  }
 };
 
 
 t1.start();
 t2.start();
 
 
}
}

Thread-0 is going to withdraw
waiting....
Thread-1 is going to  deposit
deposit completed
withdraw completed
After deposit amount is 4000
After withdraw amount is4000

• it does not support multiple inheritance directly.But it does so by using the concept of interfaces.
• Many More...

static {
        String category = "electronic trading system";
        System.out.println("example of static block in java");
    }

public class Test {

    private int count=0;
    public static void main(String args[]) throws IOException {
        StaticTest test = new StaticTest(); //accessing static variable by creating an instance of class
        test.count++;
    }  
 }

public class Test {

    private int count=0;
    public static void main(String args[]) throws IOException {
        count++; //compiler error: non-static variable count cannot be referenced from a static context
    }
}