计算一个数组列表的平均？ [英] Calculating average of an array list?

问题描述

code：

  ArrayList <Integer> marks = new ArrayList();
  Collections.addAll(marks, (Integer.parseInt(markInput.getText())));

  private void analyzeButtonActionPerformed(java.awt.event.ActionEvent evt) {
      analyzeTextArea.setText("Class average:" + calculateAverage(marks));
  }

  private int calculateAverage(List <Integer> marks) {
      int sum = 0;
      for (int i=0; i< marks.size(); i++) {
            sum += i;
      }
      return sum / marks.size();
  }

我试图用这个code来计算一组用户输入值的平均值，并在JTextArea显示，但它不能正常工作。比方说，用户输入7,4，和5，程序将显示1当它应该显示平均5.3

I'm trying to use this code to calculate the average of a set of values that a user enters and display it in a jTextArea but it does not work properly. Say, a user enters 7, 4, and 5, the program displays 1 as the average when it should display 5.3

什么是错的code？

谢谢！

推荐答案

为什么要用一个笨拙的for循环与索引当你有增强的for循环？

Why use a clumsy for loop with an index when you have the enhanced for loop?

private double calculateAverage(List <Integer> marks) {
  Integer sum = 0;
  if(!marks.isEmpty()) {
    for (Integer mark : marks) {
        sum += mark;
    }
    return sum.doubleValue() / marks.size();
  }
  return sum;
}

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