学ぶ Reading Floating-Point Numbers | Handling Different Types of Input

メニューを表示するにはスワイプしてください

When you need to read numbers with decimals—such as prices, weights, or measurements—you will use the nextDouble() method from the Scanner class. This method reads the next token from the input as a double, which is Java's data type for representing floating-point numbers. The double type allows you to handle values that have a fractional component, unlike integers which only represent whole numbers. Using nextDouble() is straightforward: after creating your Scanner object, call this method when you expect the user to input a decimal number. This is especially useful for applications that require calculations involving money, scientific data, or any measurement that isn't always a whole number.

PriceReader.java


              123456789101112131415
            
package com.example;
import java.util.Scanner;

public class PriceReader {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        System.out.print("Enter the price of the item: ");
        double price = scanner.nextDouble();

        System.out.println("You entered: $" + price);

        scanner.close();
    }
}

It is important to understand the distinction between nextInt() and nextDouble() when reading user input. The nextInt() method is designed to read whole numbers—values without any decimal point. If you try to use nextInt() when the user enters a value like 3.99, the program will throw an error because nextInt() cannot process the fractional part. In contrast, nextDouble() is specifically made to handle numbers that include a decimal point. Use nextInt() for counts, ages, or anything that must be a whole number, and use nextDouble() for prices, measurements, or any value that may include decimals.

すべて明確でしたか？

フィードバックありがとうございます！

セクション 2. 章 2

AIに質問する

何でも質問するか、提案された質問の1つを試してチャットを始めてください

セクション 2. 章 2