Question

我不明白怎么了。肯定是的。我只是菜鸟。我的想法是输入所有这些参数，然后在TestMyInteger类上运行它。我在线程“主要” java.lang.NoClassDefFoundError中遇到主要错误异常：MyInteger 在TestMyInteger.main（TestMyInteger.java:3）原因：java.lang.ClassNotFoundException：MyInteger

我不知道我的代码出了什么问题

   public class MyInteger {
     private int value;


   public MyInteger (int value) {
     this.value = value;
  } //myInteger

 public int getValue() {
    return value;
   }//getValue

   public boolean isEven() {
     return (value % 2 == 0);

   }//isEven(not static)

   public boolean isOdd() {
     return (value % 2 != 0);

   }//isOdd(not static)

  public boolean isPrime() {
     int i = 0;
          for(i = 2; i <= value / 2; i++){
              if(value % i != 0)
                return true;
         }
          return false;

   }//isPrime (not static)

   public static boolean isEven (int n) {
      return (n % 2 == 0);

   }//isEven(static)

   public static boolean isOdd(int n) {
     return (n % 2 != 0);

  }//isOdd(static)

   public static boolean isPrime(int n) {
     int i = 0;
        for(i = 2; i <= n / 2; i++){
            if(n % i != 0)
                return true;
        }
        return false;

   }//isPrime(static)

    public static boolean isEven(MyInteger n) {
       return n.isEven();

    }// myInteger isEven

    public static boolean isPrime(MyInteger o) {
     int i = 0;
          for(i = 2; i <= o / 2; i++){
            if(o % i != 0)
                return true;
        }
        return false;

   } //myInteger prime

   public static boolean isOdd(MyInteger o) {
     return (o % 2 != 0);
   }//MyInteger isOdd

  public boolean equals(int anotherNum) {
   if (n1 == n2)
     return true;
      return false;
   } //what value is this (equals)

    public boolean equals(MyInteger o) {
      if (n1 == n2)
       return true;
       return false;

   `enter code here` }//MyInteger equals

   }

所有这些都将在此TestMyInteger类上运行

public class TestMyInteger {
 public static void main(String[] args) {
   MyInteger n1 = new MyInteger(5);
   System.out.println("n1 is even? " + n1.isEven());
   System.out.println("n1 is prime? " + n1.isPrime());
   System.out.println("15 is prime? " + MyInteger.isPrime(15)); 
   System.out.println("15 is even? " + MyInteger.isEven(15));

   MyInteger n2 = new MyInteger(24);
   System.out.println("n2 is odd? " + n2.isOdd()); 
   System.out.println("45 is odd? " + MyInteger.isOdd(45)); 
   System.out.println("n1 is equal to n2? " + n1.equals(n2));
   System.out.println("n1 is equal to 5? " + n1.equals(5)); 
   System.out.println("n2 is even? " + MyInteger.isEven(n2)); 
   System.out.println("n2 is odd? " + MyInteger.isOdd(n2)); 
   System.out.println("n2 is prime? " + MyInteger.isPrime(n2)); 
 }
}//TestMyInteger

Answer 1

委托，请不要一遍又一遍地重新实施相同的方法。为了从value实例访问MyInteger，您需要使用instance.value。您的isPrime逻辑似乎是相反的。不要尝试更改Object.equals(Object)的签名。如果您打算覆盖equals，则也应该覆盖hashCode和toString。喜欢，

public class MyInteger {
    private int value;

    public MyInteger(int value) {
        this.value = value;
    } // myInteger

    public int getValue() {
        return value;
    }// getValue

    public boolean isEven() {
        return isEven(value);
    }// isEven(not static)

    public boolean isOdd() {
        return isOdd(value);
    }// isOdd(not static)

    public boolean isPrime() {
        return isPrime(value);
    }// isPrime (not static)

    public static boolean isEven(int n) {
        return (n % 2 == 0);
    }// isEven(static)

    public static boolean isOdd(int n) {
        return !isEven(n);
    }// isOdd(static)

    public static boolean isPrime(int n) {
        for (int i = 2; i <= n / 2; i++) {
            if (n % i == 0) {
                return false;
            }
        }
        return true;
    }// isPrime(static)

    public static boolean isEven(MyInteger n) {
        return isEven(n.value);
    }// myInteger isEven

    public static boolean isPrime(MyInteger o) {
        return isPrime(o.value);
    } // myInteger prime

    public static boolean isOdd(MyInteger o) {
        return isOdd(o.value);
    }// MyInteger isOdd

    public boolean equals(int anotherNum) {
        return value == anotherNum;
    } // what value is this (equals)

    @Override
    public boolean equals(Object o) {
        if (o instanceof MyInteger) {
            return equals(((MyInteger) o).value);
        }
        return false;
    }// MyInteger equals

    @Override
    public int hashCode() {
        return Integer.hashCode(value);
    }

    @Override
    public String toString() {
        return String.valueOf(value);
    }
}

除非可以编译MyInteger，否则不能使用MyInteger。电脑不知道怎么办。

Answer 2

public final class MyInteger {

    private final int value;

    public MyInteger(int value) {
        this.value = value;
    }

    public int getValue() {
        return value;
    }

    public boolean isEven() {
        return isEven(value);
    }

    public boolean isOdd() {
        return isOdd(value);

    }

    public boolean isPrime() {
        return isPrime(value);
    }

    public static boolean isEven(int value) {
        return value % 2 == 0;
    }

    public static boolean isOdd(int value) {
        return !isEven(value);
    }

    public static boolean isPrime(int value) {
        if (Math.abs(value) < 2)
            return false;

        for (int i = 2, max = (int)Math.sqrt(value); i <= max; i++)
            if (value % i == 0)
                return false;

        return true;
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj)
            return true;
        return obj instanceof MyInteger && value == ((MyInteger)obj).value;
    }

    @Override
    public int hashCode() {
        return Objects.hash(value);
    }

    @Override
    public String toString() {
        return String.valueOf(value);
    }
}

我是否搞砸了构造函数/方法？

2 个答案: