我尝试了实现接口。但搜索接口名称为null。请帮忙。 [英] I tried implementing interfaces. But the search for interface name gave null. Please help.

问题描述

  import  java.util。*; 
  public   class  TestClass {
  public   static   String  interfaceName; 
  public   static   void  main （ String  [] args）{
 
 MyCalculator my_calculator = new MyCalculator（）; 
 Scanner nw = new Scanner（System.in）; 
  int  no = nw.nextInt（）; 
 
 System.out.println（ 我实现了 + interfaceName）; 
 System.out.print（my_calculator.divisor_sum（no））; 
 
} 
 
 静态  void  ImplementedInterfaceNames（Object o）{
 Class [] theInterfaces = o.getClass（）。getInterfaces（）; 
  for （ int  i =  0 ; i< theInterfaces.length; i ++）{
 interfaceName = theInterfaces [i] .getName（）;} 
} 
} 
 
  interface  AdvancedArithmatic {
  int  divisor_sum（ int  N）; 
} 
 
  class  MyCalculator  implements  AdvancedArithmatic {
 
  @覆盖 
  public   int  divisor_sum（ int  n）{
  int  mySum = 0; 
  for （ int  i = 1; i< = n; i ++）{
  if （n％i == 0）mySum + = i; 
} 
  return  mySum; 
} 
} 

我的尝试：

  import  java.util。*; 
  public   class  TestClass {
  public   static   String  interfaceName; 
  public   static   void  main （ String  [] args）{
 
 MyCalculator my_calculator = new MyCalculator（）; 
 Scanner nw = new Scanner（System.in）; 
  int  no = nw.nextInt（）; 
 
 System.out.println（ 我实现了 + interfaceName）; 
 System.out.print（my_calculator.divisor_sum（no））; 
 
} 
 
 静态  void  ImplementedInterfaceNames（Object o）{
 Class [] theInterfaces = o.getClass（）。getInterfaces（）; 
  for （ int  i =  0 ; i< theInterfaces.length; i ++）{
 interfaceName = theInterfaces [i] .getName（）;} 
} 
} 
 
  interface  AdvancedArithmatic {
  int  divisor_sum（ int  N）; 
} 
 
  class  MyCalculator  implements  AdvancedArithmatic {
 
  @覆盖 
  public   int  divisor_sum（ int  n）{
  int  mySum = 0; 
  for （ int  i = 1; i< = n; i ++）{
  if （n％i == 0）mySum + = i; 
} 
  return  mySum; 
} 
} 

解决方案

显示 null 因为 interfaceName 永远不会得到一个值：它会得到一个值 ImplementedInterfaceNames 会被调用，但它永远不会被调用。



此外，不是使用静态变量来为方法提供输出值，最好使用 return 语句：从方法中返回值（Java™教程>学习Java语言>类和对象） [ ^ ]

import java.util.*;
public class TestClass {
  public static String interfaceName;
	 public static void main(String[] args) { 
		
        MyCalculator my_calculator=new MyCalculator();
        Scanner nw=new Scanner(System.in);
        int no=nw.nextInt();

        System.out.println("I implemented "+interfaceName);
        System.out.print(my_calculator.divisor_sum(no));

    }

    static void ImplementedInterfaceNames(Object o){
        Class[] theInterfaces = o.getClass().getInterfaces();
        for (int i = 0; i < theInterfaces.length; i++){
            interfaceName = theInterfaces[i].getName();}
    }
}

interface AdvancedArithmatic{
    int divisor_sum(int n);
}

class MyCalculator implements AdvancedArithmatic{

    @Override
    public int divisor_sum(int n) {
        int mySum=0;
        for(int i=1;i<=n;i++){
            if(n%i==0) mySum+=i;
        }
        return mySum;
    }
}

What I have tried:

import java.util.*;
public class TestClass {
  public static String interfaceName;
	 public static void main(String[] args) { 
		
        MyCalculator my_calculator=new MyCalculator();
        Scanner nw=new Scanner(System.in);
        int no=nw.nextInt();

        System.out.println("I implemented "+interfaceName);
        System.out.print(my_calculator.divisor_sum(no));

    }

    static void ImplementedInterfaceNames(Object o){
        Class[] theInterfaces = o.getClass().getInterfaces();
        for (int i = 0; i < theInterfaces.length; i++){
            interfaceName = theInterfaces[i].getName();}
    }
}

interface AdvancedArithmatic{
    int divisor_sum(int n);
}

class MyCalculator implements AdvancedArithmatic{

    @Override
    public int divisor_sum(int n) {
        int mySum=0;
        for(int i=1;i<=n;i++){
            if(n%i==0) mySum+=i;
        }
        return mySum;
    }
}

解决方案

It shows null because interfaceName never gets a value: it would get a value of ImplementedInterfaceNames would get called, but it never gets called.

Also, instead of using a static variable for a method to give its output values, it's better practice to use a return statement in your method: Returning a Value from a Method (The Java™ Tutorials > Learning the Java Language > Classes and Objects)[^]

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