Question

如何计算数组中的元素数量？

因此数组可以容纳10个元素，但并非所有元素都被填充。如何计算输入的元素数量？

另外，找到数组平均值的正确方法是什么？我现在拥有的就是这个，

输入的有效成绩数为10 [D @ 7ea987ac [D @ 7ea987acAverage：0.0

//validate strings entered by user         
     if(convertedInput >= 0 && convertedInput <=100){
      ValidArray[validArraycount] = convertedInput;
      validArraycount ++; 
     }
  }      
  catch(NumberFormatException e){
  }

     //Prints number of valid values entered
       System.out.println("The number of valid grades entered is " + vArrayLen);



     //for printing array backwards
     for (int i = (arraycount-1); i>=0; i--){
        System.out.print(ValidArray);

     } 
     //calculates sum of all values in array of ValidArray (of grades)
     for(double d : ValidArray){
        sum += d;
     }

      //avergae of valid number array 
     double average = (sum/ValidArray.length);

     System.out.println("Average: " + average);
  } 
}

谢谢。

编辑：输入最多为10个字符串。任何东西都可以输入。有效字符串是0-10之间的双数，可以是0和10.所有字符串无效都将被丢弃。截至目前，这是我的代码：

import java.util.*;
public class Grades{
   public static void main(String args[]){

  int arraycount = 0;
  final int SIZE = 100;
  int validArrayCount = 0;
  final int ValidArraySize = 100;
  int valuesinValidArray = 0; 


  Scanner reader = new Scanner(System.in);
  String initialInput = new String ("");

  String [] sArray = new String[SIZE];
  double [] ValidArray = new double[ValidArraySize];

  double sum = 0; 

  boolean exit = false;

  System.out.println("You may enter up to 100 grades."); 
  System.out.println("When you are done entering grades, press the enter/return key.");


  //Prints to user. Stops if nothing is entered.
  while((arraycount < SIZE)&&(exit == false)){ 
     System.out.println("Enter line " + (arraycount+1) + ": "); 
     initialInput = reader.nextLine();  


     if (initialInput.length()<1){ 
        exit = true; 
     }
     else{
        sArray[arraycount]=initialInput; 
        arraycount++;
     }
  }

     //convert string to double 
  try{
     double convertedInput = Double.parseDouble(initialInput);

     //validate strings entered by user         
     if(convertedInput >= 0 && convertedInput <=100){
        ValidArray[validArrayCount] = convertedInput;
        validArrayCount ++;
     }
  }
  catch(NumberFormatException e){
  }
     //Prints number of valid values entered
       System.out.println("The number of valid grades entered is " + vArrayLen);



     //for printing array backwards
     for (int i = (ValidArraySize-1); i>=0; i--){
        System.out.println(ValidArray[i] + "");
     } 

     //calculates sum of all values in array of ValidArray (of grades)
     for(double d : ValidArray){
        sum += d;
     }

      //avergae of valid number array 
     double average = (sum/validArrayCount);

     System.out.println("Average: " + average); 
  } 
}

Answer 1

你已经在做了，ValidArray也是一个可怕的名字。您忘记在for循环中使用数组索引，而您使用的数字是validArraycount -

// Prints number of valid values entered
System.out.println("The number of valid grades entered is "
        + validArraycount);

// for printing array backwards
for (int i = validArraycount-1; i>=0; i--){
    System.out.print(ValidArray[i] + " "); // <-- don't forget the index.
} 
System.out.println(); // <-- next line.
double sum = 0;
// sum the values in array of ValidArray (of grades)
for(double d : ValidArray){
    sum += d;
}
// Average. Sum / the count 
double average = (sum / validArraycount);
System.out.println("Average: " + average);

Answer 2

validArrayCount已经包含输入的元素数量。

打印vArrayLen：

，而不是打印validArrayCount输入的有效成绩数量。

System.out.println("The number of valid grades entered is " + validArrayCount);

要获得平均值，您可以除以validArrayCount而不是ValidArray.length：

double average = (sum/validArrayCount);

此外，您必须在向后打印数组时添加数组索引：

// for printing array backwards
for (int i = validArrayCount-1; i>=0; i--){
    System.out.print(ValidArray[i] + " ");
}
System.out.println(); //For inserting a new line after printing all array elements

如何计算添加到数组中的元素数量并查找Java中添加的数字的平均值？

2 个答案: