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,

0:04

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

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

So when we run our program,

0:12

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

we see the stack trace.

0:14

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

Now,

0:15

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

in real applications,

0:16

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

when we catch these exceptions,

0:18

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

quite often we want to log them somewhere.

0:20

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

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

0:23

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

So sometime in the future,

0:24

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

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

0:28

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

Now, login is a completely separate topic.

0:30

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

Let's not worry about it for now.

0:31

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

Instead,

0:32

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

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,

0:37

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

I'm going to print logging.

0:39

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

Now let's run our program.

0:41

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

So we see the login message,

0:45

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

but something is missing.

0:46

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.

0:53

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

They click the deposit button,

0:55

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

but nothing happens.

0:56

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

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

1:04

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

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.

1:09

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

So in situations like this,

1:11

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

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

1:16

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

can get it and display a generic error message.

1:18

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

So in this catch block,

1:20

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

we type throw e.

1:23

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

We are re -throwing this exception object.

1:27

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

Now we have a compilation error.

1:30

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

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

1:34

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

In this case,

1:35

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

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

1:39

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

we want the color of this code to handle it.

1:42

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

So to fix this problem,

1:44

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

we specify this exception in the declaration of this method.

1:48

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

So we type throws IO exception.

1:52

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

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

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

Now we put the carrot over here,

1:59

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

alt and enter.

2:01

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

So far we use this command,

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

surround with try -catch,

2:04

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

we can use add exception to method signature.

2:06

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

There you go.

2:07

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

Now,

2:08

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in our main method,

2:10

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

we need to cache this exception.

2:12

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

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

2:15

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

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

2:20

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

unexpected error occur.

2:23

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

like desktop or mobile applications,

2:26

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

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

2:30

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

and displays a generic error message.

2:32

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

Now here we're catching an IO exception,

2:35

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

we can make this more general by catching exception objects or

2:39

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throwable objects.

2:41

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

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

2:45

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

of all exceptions and errors in Java applications.

2:49

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

So with this,

2:49

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

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

2:53

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

our program displays a generic error message to the user.

2:56

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

Now let's run.

2:58

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

So,

3:00

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

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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