throw,throws,finally

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We are going to explaining What is throw,throws,finally in java?

throws

• throws clause in used to declare an exception and postpone the handling of a checked exception
• throws clause is used to declare checked and un-checked exceptions
• throws clause is followed by exception class names.
• throws clause is used in method

Syntax

public void  getData() throws FileNotFoundException{
//To do something
}

• We can declare multiple exceptions by using throws clause

Syntax

public void  getData() throws IOException, FileNotFoundException, SQLException {
   //To do something
}

throw

• throw keyword is used to throw an exception explicitly.
• throw is followed by an instance variable
• throw is used inside method body to invoke an exception

Syntax

public void  getData(){
try {
  throw new Exception("Exception occured.");
} catch (Exception exp) {
  System.out.println("Error: "+exp.getMessage());
}
}

• We cannot throw more than one exception by using throw clause

Syntax

throw new ArithmeticException("An integer should not be divided by zero!!")
throw new IOException("Connection failed!!")

Finally

• The finally block follows a try block or a catch block.

Syntax

Combination 1

try{
//To do something
}finally{
//To do something
}
Combination 2

try{
//To do something
}catch(Exception e){
//To do something
}finally{
//To do something
}
Combination 3
try{
//To do something
}catch(ExceptionType1 e1){
//To do something
}catch(ExceptionType2 e2){
//To do something
}catch(ExceptionType3 e3){
//To do something
}finally{
//To do somehting
}

• Using a finally block allows you to run any cleanup-type statements, closing connections and resources, releasing memory even if we got exception in the method.
• A finally block of code always executes, irrespective of occurrence of an Exception.
• A finally of code will not executes in some cases like System.exit(0), System.exit(1). These statements will terminate the program forcefully and control will not reach finally block.