10- Re-throwing Exceptions

Jun 18, 2026 09:19 · 3:07 · English · Whisper Turbo · 2 speakers

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Lecture Index

0:03

S… Speaker 1 (10- Re-throwing Exceptions)

In this program,

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S… Speaker 1 (10- Re-throwing Exceptions)

we are depositing a negative value in our account.

0:06

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We catch an IO exception and then print the stack trace.

0:10

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So when we run our program,

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we see the stack trace.

0:14

S… Speaker 2 (10- Re-throwing Exceptions)

Now,

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in real applications,

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when we catch these exceptions,

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quite often we want to log them somewhere.

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We want to store them in a file or in a database.

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So sometime in the future,

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we can come back and see what errors we had in our application.

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Now, login is a completely separate topic.

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Let's not worry about it for now.

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Instead,

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let's simulate logging by printing a message on a terminal.

0:35

S… Speaker 1 (10- Re-throwing Exceptions)

So instead of printing the stack trace,

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I'm going to print logging.

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Now let's run our program.

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So we see the login message,

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S… Speaker 1 (10- Re-throwing Exceptions)

but something is missing.

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S… Speaker 1 (10- Re-throwing Exceptions)

We're not telling the user that an error occurred.

0:49

S… Speaker 1 (10- Re-throwing Exceptions)

So let's imagine the user tries to deposit a negative value.

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They click the deposit button,

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but nothing happens.

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The application is not crashing.

0:57

S… Speaker 1 (10- Re-throwing Exceptions)

It's not displaying an error either.

1:00

S… Speaker 1 (10- Re-throwing Exceptions)

So, the reason this is happening is because we're catching

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this exception over here.

1:05

S… Speaker 1 (10- Re-throwing Exceptions)

So we handle it and then the application will continue the normal execution.

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S… Speaker 1 (10- Re-throwing Exceptions)

So in situations like this,

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we should re -throw that exception so somewhere else in the application we

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can get it and display a generic error message.

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So in this catch block,

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we type throw e.

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We are re -throwing this exception object.

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Now we have a compilation error.

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the Java compiler is saying that we haven't handled the IO exception here.

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S… Speaker 1 (10- Re-throwing Exceptions)

In this case,

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we don't want to wrap this inside the try catch block because when we throw an exception,

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S… Speaker 1 (10- Re-throwing Exceptions)

we want the color of this code to handle it.

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So to fix this problem,

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we specify this exception in the declaration of this method.

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So we type throws IO exception.

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Now we can also have IntelliJ do this for us.

1:56

S… Speaker 1 (10- Re-throwing Exceptions)

So let me delete this.

1:57

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Now we put the carrot over here,

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alt and enter.

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So far we use this command,

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surround with try -catch,

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we can use add exception to method signature.

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There you go.

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Now,

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in our main method,

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we need to cache this exception.

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So let's wrap it with a try -catch block,

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and this is where we can print a generic error message like an

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unexpected error occur.

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like desktop or mobile applications,

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you have a generic exception handler that catches all kinds of exceptions

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and displays a generic error message.

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Now here we're catching an IO exception,

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we can make this more general by catching exception objects or

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throwable objects.

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So earlier I told you that the throwable class is the parent

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of all exceptions and errors in Java applications.

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So with this,

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we'll make sure that no matter what kind of error or exception we get,

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our program displays a generic error message to the user.

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Now let's run.

2:58

S… Speaker 2 (10- Re-throwing Exceptions)

So,

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we logged the exception and printed a friendly message to the user.

This transcript was generated by AI (automatic speech recognition). May contain errors — verify against the original audio for critical use. AI policy

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