元素总和ArrayList [英] Sum of the elements ArrayList

问题描述

我是Java的初学者，正在尝试获取ArrayList中所有元素的总和.我通过使用方法来执行此操作，并在该方法中得到此错误:

Im a beginner in Java and trying to get the sum of all the elements in the ArrayList. Im doing it by using a method and get this error in the method:

二进制操作数"+"的错误操作数类型，第一种类型:int，第二种 类型:对象"

"bad operand types for binary operatpr '+' first type: int, second type: Object"

我不知道我在做什么错，谢谢您的帮助！

I don't know what I'm doing wrong here, appreciate any help!

public static int sumNumbers(ArrayList numbers){
    int sum = 0;
    for(int i = 0; i<numbers.size(); i++){
        sum+=numbers.get(i);
   }
    return sum;
}

推荐答案

将numbers声明为ArrayList<Integer> numbers. 然后Integer将被取消装箱到int.现在，您的arraylist包含的objects可能不是int s.

Declare numbers as ArrayList<Integer> numbers. Then the Integer will be unboxed to int. Right now, your arraylist contains objects that may not be ints.

目前，numbers.get()将返回object，并且您不能直接将object添加到int.

For the moment, numbers.get() will return an object, and you can not add an object to an int directly.

您始终可以将元素强制转换为Integer，但我建议使用第一个选项.

You could always cast the element to Integer, but I would recommend the first option.

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