JAVA EXAMPLE PROGRAMS

Throw Clause Examples

Use 'throw' statement to throw an exception or simply use the throw clause with an object reference to throw an exception.
The syntax is 'throw new Exception();'. Even you can pass the error message to the Exception constructor.

Below example shows how to throw an exception.

Throw Clause Sample Code

Code:

package com.myjava.exceptions;

public class MyExplicitThrow {
    public static void main(String a[]){
        try{
            MyExplicitThrow met = new MyExplicitThrow();
            System.out.println("length of JUNK is "+met.getStringSize("JUNK"));
            System.out.println("length of WRONG is "+met.getStringSize("WRONG"));
            System.out.println("length of null string is "+met.getStringSize(null));
        } catch (Exception ex){
            System.out.println("Exception message: "+ex.getMessage());
        }
    }
    
    public int getStringSize(String str) throws Exception{
        if(str == null){
            throw new Exception("String input is null");
        }
        return str.length();
    }
}

Example Output

length of JUNK is 4
length of WRONG is 5
Exception message: String input is null

Other Exception Handling Examples

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Knowledge Centre

Can we call servlet destory() from service()?

As you know, destory() is part of servlet life cycle methods, it is used to kill the servlet instance. Servlet Engine is used to call destory(). In case, if you call destory method from service(), it just execute the code written in the destory(), but it wont kill the servlet instance. destroy() will be called before killing the servlet instance by servlet engine.

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If you don’t make mistakes, you’re not working on hard enough problems. And that’s a big mistake.

-- Frank Wilczek

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About Author

I'm Nataraja Gootooru, programmer by profession and passionate about technologies. All examples given here are as simple as possible to help beginners. The source code is compiled and tested in my dev environment.

If you come across any mistakes or bugs, please email me to [email protected].

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Reference: Java™ Platform Standard Ed. 7 - API Specification | Java™ Platform Standard Ed. 8 - API Specification | Java is registered trademark of Oracle.