Parsing numeric arguments in Java - Step-by-Step Execution

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Concept Flow - Parsing numeric arguments

Start: Receive String input

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Try to convert String to number

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Success

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Use number

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End

The program receives a string input, tries to convert it to a number, and either uses the number or handles an error if conversion fails.

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Execution Sample

Java

String input = "123";
int number = Integer.parseInt(input);
System.out.println(number);

This code converts the string "123" to the number 123 and prints it.

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Execution Table

Step	Action	Input Value	Result	Output/Exception
1	Receive input string	"123"	String stored	No output
2	Call Integer.parseInt	"123"	Parsed integer 123	No exception
3	Print number	123	Printed 123	Output: 123
4	End	-	-	Program ends normally

💡 Parsing succeeds and program ends after printing the number.

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Variable Tracker

Variable	Start	After Step 1	After Step 2	After Step 3	Final
input	null	"123"	"123"	"123"	"123"
number	undefined	undefined	123	123	123

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Key Moments - 2 Insights

▶What happens if the input string is not a valid number?

▶Why do we need to convert the string to a number?

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Visual Quiz - 3 Questions

Look at the execution table, what is the value of 'number' after Step 2?

A undefined

B "123"

C 123

D NumberFormatException

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Concept Snapshot

Parsing numeric arguments in Java:
- Use Integer.parseInt(string) to convert text to int.
- If string is not a valid number, NumberFormatException occurs.
- Always handle exceptions for safe parsing.
- Parsed number can be used for calculations or output.

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Full Transcript

This example shows how Java converts a string input to a number using Integer.parseInt. The program starts by receiving a string "123". Then it calls Integer.parseInt to convert this string to the integer 123. After conversion, it prints the number. If the string was not a valid number, an exception would occur. This process is important because user inputs are text, and to work with numbers, conversion is needed.