java - 根据条件要求，用户输入的错误输出

Question

我的程序应该打印出所有 3 岁以上的有爪猫的名字和年龄。对于以下输入

Enter the name of Cat 1: Sam
Enter the age of Cat 1: 1
Enter the weight of Cat 1: 5
Enter the breed of Cat 1: fluffy1
Does the cat have claws? True or False?: True

Enter the name of Cat 2: Tom 
Enter the age of Cat 2: 4
Enter the weight of Cat 2: 5
Enter the breed of Cat 2: fluffy2
Does the cat have claws? True or False?: True

Enter the name of Cat 3: Bob
Enter the age of Cat 3: 5
Enter the weight of Cat 3: 5
Enter the breed of Cat 3: fluffy3
Does the cat have claws? True or False?: False

输出应该是这样的。

The Cats over 3 with claws are:
Name: Tom
Age: 4 Years Old

但是，程序结束时没有任何输出。这是我执行的代码。

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.IOException;

public class MyClass {

    private static Cat[] catArray = new Cat[3];
    public static void main(String[] args) throws IOException {

        for (int i=0;i<3;i++) {
            Cat cat = new Cat();
            BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
            System.out.print("Enter the Name of Cat " + (i+1) + ": ");
            cat.setName(in.readLine());
            System.out.print("Enter the Age of Cat " + (i+1) + ": ");
            cat.setAge((Integer.parseInt(in.readLine())));
            System.out.print("Enter the Weight of Cat " + (i+1) + ": ");
            cat.setWeight((Double.parseDouble(in.readLine())));
            System.out.print("Enter the Breed of Cat " + (i+1) + ": ");
            cat.setBreed(in.readLine());
            System.out.print("Does the cat have claws? True or False: ");
            String hasClaws = in.readLine();
            if(hasClaws.equals("False"))
                cat.sethasClaws(false);
            else
                cat.sethasClaws(true);
            catArray[i] = cat;
        }
        for(int j=0;j<3;j++) {
            if((catArray[j].getAge()>=3) && (!catArray[j].hasClaws()) ) {
                System.out.println("The cats over 3 with claws are: \n");
                System.out.println("Name: " + catArray[j].getName());
                System.out.println("Age: " + catArray[j].getAge() + " years old");
            }
        }
    }
}

还有:

public class Cat {
    private String name;
    private int age;
    private double weight;
    private String breed;
    private boolean hasClaws;

    public Cat() {}

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public double getWeight() {
        return weight;
    }

    public void setWeight(double weight) {
        this.weight = weight;
    }

    public String getBreed() {
        return breed;
    }

    public void setBreed(String breed) {
        this.breed = breed;
    }

    public boolean hasClaws() {
        return hasClaws;
    }

    public void sethasClaws(boolean hasClaws) {
        this.hasClaws = hasClaws;
    }
}

Answer 1

我相信 (catArray[j].getAge()>=3) && (!catArray[j].hasClaws()) 中的 ! 运算符是把你搞砸了。这等同于“显示所有 3 岁或以上的没有爪子的猫”。

来自:https://docs.oracle.com/javase/tutorial/java/nutsandbolts/opsummary.html

! Logical complement operator; inverts the value of a boolean

试试这个:

for(int j=0;j<3;j++) {
    if((catArray[j].getAge()>=3) && (catArray[j].hasClaws()) ) {
        System.out.println("The cats over 3 with claws are: \n");
        System.out.println("Name: " + catArray[j].getName());
        System.out.println("Age: " + catArray[j].getAge() + " years old");
    }
}