6- Catching Multiple Types of Exceptions

Jun 18, 2026 03:55 · 4:28 · English · Whisper Turbo · 2 speakers

This transcript expires in 21 рӯзҳо. Навсозии барои захираи доимӣ →

Lecture Index

0:03

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Sometimes we need to catch multiple types of exceptions.

0:06

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

For example,

0:07

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

after reading a file,

0:08

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

let's call reader .read.

0:11

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

This reads one character and returns its numeric value.

0:15

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So let's store it in a variable called value.

0:18

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Now here we have another compilation error because we haven't

0:22

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

handled the IO exception.

0:24

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So this read method may throw an IO exception if it cannot read

0:28

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

data from this file.

0:29

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

To solve this problem,

0:30

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

we need to type another catch clause here.

0:33

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So catch,

0:34

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

like here we want to catch an IO exception,

0:36

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

we give it a name,

0:38

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

and in this block,

0:40

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

we can print a message like,

0:42

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

could not read data.

0:44

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

The exception is gone.

0:47

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Now we have multiple catch blocks,

0:49

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

and each catch block targets a specific type

0:53

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

of exception.

0:54

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So only one of these will be executed.

0:57

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

In this case,

0:58

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

we try to open a file that doesn't exist,

1:01

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

so this line will throw a file not found exception,

1:04

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

and this catch block will catch that exception.

1:08

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

Now,

1:09

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

the code inside this catch block will get executed,

1:11

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

and after that,

1:12

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

the control will move over here.

1:14

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So this second catch block will get ignored,

1:18

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

okay?

1:18

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So we have multiple catch blocks,

1:20

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

and each catch block targets a specific type of exception.

1:23

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

Now,

1:24

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

does the order of these catch blocks matter?

1:27

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Sometimes it does.

1:28

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So if I move this catch block over here,

1:31

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

you see a compilation error.

1:33

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

The Java compiler is saying that we have already caught the

1:38

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

file not found exception.

1:39

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

What does this mean?

1:40

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

Well,

1:40

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

let's look at the documentation for the file not found exception class.

1:44

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So we type Java file not found exception.

1:48

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

Here it is.

1:52

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

Okay.

1:54

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So this class extends the IOException class.

1:57

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

And that means,

1:59

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

if we have a catch clause for an IOException,

2:02

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

we don't need this FindNotFoundException.

2:05

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

This is the polymorphism principle of object -oriented programming.

2:09

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

We talked about this in the second part of this course.

2:12

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Let me show you.

2:13

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

If I have a variable of type IOException,

2:16

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

let's call it X,

2:17

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

I can set this variable to a new instance of IOException or

2:21

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

any classes that extend the IOException class.

2:24

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So we can set this to a new file not found exception.

2:29

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

This is polymorphism.

2:31

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

An object may take different forms.

2:34

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

So,

2:35

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

if you have a catch clause,

2:38

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

to catch an I .O .Exception,

2:40

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

this catch clause can catch an I .O .Exception or any of its derivatives,

2:44

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

any classes that extend the I .O .Exception class.

2:47

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

Okay?

2:48

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Now sometimes we want to treat these exceptions the same way,

2:51

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

for example here we can display a generic error message,

2:54

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

but other times we want to handle them differently.

2:57

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

If that is the case,

2:58

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

then we need to bring back this catch clause and put

3:03

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

it before the first catch clause,

3:04

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

so now if we get a find not found exception,

3:08

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

we can print a message like,

3:09

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

file does not exist.

3:12

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So we are giving the user a more specific error message.

3:16

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

Now,

3:17

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

as another example,

3:19

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

let's create a new simple date format object

3:24

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

and call the parse method.

3:26

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Now here we have another compilation error,

3:29

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

because this parse method may throw an exception of type parseException.

3:34

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

Now,

3:35

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

we can put the carrot over here,

3:36

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

press alt and enter,

3:38

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

and have IntelliJ add a catch clause for us.

3:41

S… Speaker 2 (6- Catching Multiple Types of Exceptions)

There you go.

3:42

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So it's right here.

3:43

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Now we have three catch clauses.

3:47

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Let's say we want to treat all of these the same way.

3:49

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So first we can get rid of the file not found exception.

3:53

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Now we have two catch clauses.

3:55

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

We can combine this using a vertical bar.

3:58

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So right after IO exception,

4:00

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

we type a vertical bar,

4:02

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

then we type parse exception,

4:04

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

and with this we don't need the second catch clause.

4:10

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So this block can catch exceptions of type ioException or

4:14

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

parseException.

4:15

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

So these are different ways to catch multiple exceptions.

4:18

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

The approach you take really depends on your application and its requirements.

4:22

S… Speaker 1 (6- Catching Multiple Types of Exceptions)

Next we're going to talk about the finally block.

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

❤️ Шумо STT.ai- ро дӯст медоред? Ба дӯстонатон бигӯед!

Ҷамъбаст

Барои эҷоди ҷамъбасти AI- и ин нусхаи навиштаҷот, тугмаи ҷамъбастро пахш кунед.

Дар бораи ин нусхаи навиштаҷот аз AI пурсед

Дар ин ҷо ба шумо дар бораи ин раванд маълумот дода мешавад: Интихоби дурусти раванди эҷодӣ ва раванди таҳия.

& Дигарро гузарондан