Parsing numeric arguments in Java

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Introduction

Parsing numeric arguments means turning text input into numbers so the program can use them for math or decisions.

When reading numbers typed by a user in a program.

When getting numbers from command line arguments to control program behavior.

When loading numbers stored as text in files or databases.

When converting strings from web forms into numbers for calculations.

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Syntax

Java

int number = Integer.parseInt(text);
double decimal = Double.parseDouble(text);

Use Integer.parseInt to convert text to whole numbers (int).

Use Double.parseDouble to convert text to decimal numbers (double).

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Examples

line_end_arrow_notchThis converts the text "25" into the number 25.

Java

int age = Integer.parseInt("25");

line_end_arrow_notchThis converts the text "19.99" into the decimal number 19.99.

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double price = Double.parseDouble("19.99");

line_end_arrow_notchThis converts the first command line argument into an integer.

Java

int count = Integer.parseInt(args[0]);

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Sample Program

This program converts two strings into numbers and prints them.

Java

public class ParseExample {
    public static void main(String[] args) {
        String input1 = "123";
        String input2 = "45.67";

        int number = Integer.parseInt(input1);
        double decimal = Double.parseDouble(input2);

        System.out.println("Integer value: " + number);
        System.out.println("Double value: " + decimal);
    }
}

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Important Notes

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If the text is not a valid number, parsing will cause an error (NumberFormatException).

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Always check or handle errors when parsing user input to avoid crashes.

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Summary

Parsing numeric arguments converts text into numbers for use in programs.

Use Integer.parseInt for whole numbers and Double.parseDouble for decimals.

Be careful to handle invalid input to keep programs safe.