if / else语句

Question

我几天前刚刚开始使用java。我目前正在关注这个课程＆＃39; http://programmingbydoing.com。还没有遇到任何问题，但现在我陷入了任务32。

到目前为止我的代码（总是得到Squirrel而不是moose作为输出）：

import java.util.Scanner;

public class TwoQuestion32 {

public static void main(String[] args) {
    boolean animal, vegetable, mineral, smallerthan;

    String whatIsIt, biggerThan;
    Scanner keyboard = new Scanner(System.in);


    System.out.println("Hello and welcome, i've got 2 questions for you!");
    System.out.println("Think of an object and i'll try to guess it");
    System.out.println();
    System.out.println("Question 1) Is it an animal, vegetable or mineral?");
    System.out.print(">");
    whatIsIt = keyboard.nextLine();

    if (whatIsIt == "animal")
            animal = true;
            if (whatIsIt == "vegetable")
            vegetable = true;
            if (whatIsIt == "mineral")
            mineral = true;


    System.out.println("Question 2) Is it bigger than a breadbox?");
    System.out.print(">");
        biggerThan = keyboard.nextLine();
            if (biggerThan == "yes")
            smallerthan = false;
            if (biggerThan == "no"){
            smallerthan = true;}


            System.out.print("My guess is that you are thinking of a ");
        if (animal = true){
            if (smallerthan = true)
                System.out.println("squirrel");
        }else { 
                System.out.println("moose");}
}   
}

提前致谢！也希望听到如何以更智能的方式提出代码的提示。要友好，请记住我刚刚开始！

编辑：好的，我采取了另一种方法。我的第一次尝试真的很奇怪。谢谢你的帮助！

下面是工作代码：

import java.util.Scanner;

公共课题32 {

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


    String whatIsIt, whatIsIt2;
    String animal = "animal";
    String mineral = "mineral";
    String vegetable = "vegetable";
    String bigger = "yes";
    String smaller = "no";


    System.out.println("Hello and welcome, i've got 2 questions for you!");
    System.out.println("Think of an object and i'll try to guess it");
    System.out.println();
    System.out.println("Question 1) Is it an animal, vegetable or mineral?");
    System.out.print(">");
    whatIsIt = keyboard.nextLine();

    System.out.println("Question 2) Is it bigger than a breadbox?");
    System.out.print(">");
        whatIsIt2 = keyboard.nextLine();

    if (whatIsIt.equalsIgnoreCase(animal)){
        if (whatIsIt2.equalsIgnoreCase(bigger)){
            System.out.println("My guess is that you are thinking of a moose");
        }else{ System.out.println("My guess is that you are thinking of a squirrel");
        }
    }

    if (whatIsIt.equalsIgnoreCase(vegetable)){
        if (whatIsIt2.equalsIgnoreCase(bigger)){
            System.out.println("My guess is that you are thinking of a melon");
        }else{ System.out.println("My guess is that you are thinking of a carrot");
        }
    }

    if (whatIsIt.equalsIgnoreCase(mineral)){
        if (whatIsIt2.equalsIgnoreCase(bigger)){
            System.out.println("My guess is that you are thinking of a Camaro");
        }else{ System.out.println("My guess is that you are thinking of a paper clip");
        }
    }
    System.out.println("I would ask you if I'm right, but I dont actually care.");

    }


}

Answer 1

在你的if语句中，每次if (animal = true){将动物设置为true，而不是检查它（==）。 另外，对于字符串，您必须使用.equals()而不是==。