如何将数组元素从子类传递到主类

Question

import java.util.Scanner;

public class GreatestLeastAverageApp {

  public GreatestLeastAverageApp() {
    // TODO Auto-generated constructor stub
  }

  public static void main(String[] args) {

    GreatestLeastAverage number = new GreatestLeastAverage();

    int[] x = {0};
    int a = 0, b = 0;
    x = new int[a]; 
    {
      for (int i = 0; i <= a; i++) 
      {
        for (int j = 0; j <= a; j++)
          GreatestLeastAverage.a[i] = x[j]; // loop to pass  the values of the array elements to the parent class from the sub class. 
      }
    }


    Scanner keyboard = new Scanner(System.in); // for the input from the user 
    System.out.println("Enter the number of elements:");
    a = keyboard.nextInt(); // enter the number of integers to be entered so loop can run accordingly
    System.out.println("Enter a set of integers( Enter -99 to exit):");
    do // do loop so the user can input the variables until one of the variable is =-99. 
    {
      {
        for (b = 0; b <= a; b++)
          x[b] = keyboard.nextInt();
      }
    } while (x[b] != -99);

    //GreatestLeastAverage number = new GreatestLeastAverage(); // object made for parent class. 
    System.out.println("The Greatest Number is" + number.computegreatest()); // output line. 
    System.out.println("The Smallest Number is" + number.computeleast());
    System.out.println("The average is " + number.computeaverage());
    keyboard.close();
  }

}

public class GreatestLeastAverage {

  static int x; //variables declared for input in super class. 
  public static int[] a; // static variable to access in both classes.    
  int temp;
  int temp1;
  int temp2;
  int average;

  public int greatestleastaverage(int d) {
    d = x;
    return x;
  }

  public static int getarray(int[] b) {
    for (int i = 0; i <= x; i++) {
      for (int j = 0; j <= x; j++) {
        a[i] = b[j];
      }
    }
    return b[];
  }

Answer 1

使用列表。它们通常更灵活，如果正确使用ArrayList，它的性能实际上就像数组一样。

public class GreatestLeastAverage {
    // ... other private members
    private List<Integer> a = new ArrayList<Integer>();

    public List<Integer> getA() {
        return a;
    }
}

这使您可以执行以下代码：

GreatestLeastAverage gla = new GreatestLeastAverage();
for (int b = 0; b <= a; b++) {
    gla.getA().add(keyboard.nextInt());
}

如果您需要该数据用于其他用途，那么它已经在gla中了！简单地重用它。

for(int a : gla.getA()) {
    // Do something with a
}