如何将字符串转换为整数类型并从用户输入中输入 double 类型？

Question

/**

 * MadLib.java  

 *

 * @author: Jackie Hirsch

 * Assignment: Madlib

 * 

 * Brief Program Description: This program has will read a madlib with 

the inputs that the user gives the computer. 

 * 

 *

 */

import javax.swing.JOptionPane; //import of JOptionPane

public class MadLib

{

    public static void main (String[] args)

    {

        String cheeseType; //Cheese Character

        String interjection; //interjection

        String treeType; //tree type

        String wholeNumberFriends; // number for number of friends on 

        //line 27

        String numberMiles; //number of miles

        int wholeNumberFriendsConverted; // number for number of 

        //friends on line 27 converted

        double numberMilesConverted; //number of miles

        //ask user for variable string cheese type

        cheeseType = JOptionPane.showInputDialog ("Enter a type of 

        cheese");

        //ask user for varaible string interjection

        interjection = JOptionPane.showInputDialog ("Enter an 

        interjection");

        //ask user for variable string tree type

        treeType = JOptionPane.showInputDialog ("Enter a type of 

        tree");

        //ask user for variable integer number for number of friends

        wholeNumberFriends = JOptionPane.showInputDialog ("Enter a 

        whole number");

        //ask user for variable double number for number of miles

        numberMiles = JOptionPane.showInputDialog ("Enter a decimal or 

        whole number");

        //string converted

        wholeNumberFriends = Integer.parseInt 

        (wholeNumberFriendsConverted);

        numberMiles = Integer.parseInt (numberMilesConverted);

    }

}

**你好。这周我刚刚在高中计算机科学课上开始学习如何编写 Java 代码。我正在尝试将字符串转换为双精度和整数。我要转换的两个变量是 wholeNumberFriends（整数）和 numberMiles（双精度）。我为它们中的每一个都创建了一个新变量，以便它们可以轻松转换为双精度和整数。我不断收到此转换的错误是，类型不兼容： double 无法转换为 java.lang.String 。谢谢你。**

Answer 1

字符串转整数int num = Integer.parseInt("1");字符串加倍double num = Double.parseDouble("1.2");

Answer 2

您可以使用Integer.valueOf(java.lang.String)       String userInput = "2";        try {            Integer.valueOf(userInput);        } catch (NumberFormatException e) {            // Not a Number        }同样的valueOf方法是可用的Double，Float，Long等。该valueOf方法将返回一个对象而不是原始对象。