Multiple catch blocks in Java - Step-by-Step Execution

Concept Flow - Multiple catch blocks

Try block starts

↓

Exception occurs?

No→Try block ends normally

Yes↓

Check first catch block

↓

Matches exception?

No→Check next catch block

Yes↓

Execute catch block

↓

Continue after try-catch

The program tries code in the try block. If an exception happens, it checks each catch block in order to find a match and runs the matching one.

Execution Sample

Java

try {
    int[] arr = new int[2];
    System.out.println(arr[5]);
} catch (ArrayIndexOutOfBoundsException e) {
    System.out.println("Index error");
} catch (Exception e) {
    System.out.println("General error");
}

This code tries to access an invalid array index, catches the specific index error first, and prints a message.

Execution Table

Step	Action	Exception Thrown	Catch Block Checked	Catch Block Matches?	Output
1	Enter try block	None	None	N/A
2	Access arr[5]	ArrayIndexOutOfBoundsException	First catch (ArrayIndexOutOfBoundsException)	Yes
3	Execute first catch block	Handled	First catch	Yes	Index error
4	Exit try-catch	Handled	None	N/A

💡 Exception handled by first catch block, program continues after try-catch.

Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
arr	null	new int[2]	new int[2]	new int[2]	new int[2]
Exception	none	none	ArrayIndexOutOfBoundsException	handled	none

Key Moments - 2 Insights

Why does the first catch block run instead of the second?

Because the exception thrown is ArrayIndexOutOfBoundsException, which matches the first catch block exactly, so Java runs it and skips the others (see execution_table step 2 and 3).

What happens if no catch block matches the exception?

The exception would propagate up and could crash the program if not handled elsewhere. In this example, all exceptions are caught by the second catch block if the first doesn't match.

Visual Quiz - 3 Questions

Look at the execution table, which catch block handles the exception at step 3?

A The first catch block (ArrayIndexOutOfBoundsException)

B The second catch block (Exception)

C No catch block handles it

D Both catch blocks handle it

💡 Hint

Check the 'Catch Block Matches?' and 'Output' columns at step 3 in the execution_table.

At which step is the exception first detected?

A Step 1

B Step 2

C Step 3

D Step 4

💡 Hint

Look at the 'Exception Thrown' column in the execution_table.

If the first catch block was removed, which catch block would handle the exception?

A No catch block would handle it

B A new catch block would be needed

C The second catch block (Exception)

D The program would crash immediately

💡 Hint

See that the second catch block catches Exception, which is a parent of ArrayIndexOutOfBoundsException.

Concept Snapshot

try {
  // code that might throw exceptions
} catch (SpecificException e) {
  // handle specific exception
} catch (GeneralException e) {
  // handle other exceptions
}
Multiple catch blocks let you handle different errors separately, checked in order.

Full Transcript

This example shows how Java tries code inside a try block. If an error happens, it looks at each catch block in order to find one that matches the error type. The first matching catch block runs, handling the error. Here, accessing an invalid array index throws ArrayIndexOutOfBoundsException, which matches the first catch block, so it prints 'Index error'. The program then continues normally after the try-catch. If no catch block matches, the error would go up and might crash the program. Multiple catch blocks let you handle different errors in different ways.