创建具有可变数据类型的数组

Question

**Initializing an array of NaturalNumbers with values 1 through 4**

When I debug, I find the array = [5,5,5,5] and my goal is that the array = [1,2,3,4].

        NaturalNumber[] array = new NaturalNumber[4];
        NaturalNumber count = new NaturalNumber2(1);
        for (int i = 0; i < array.length; i++) {
            array[i] = count;

            count.increment();

Here is a link to all the methods that can be used with natural numbers. I just do not understand how can I create the wanted array without changing count 's value.

http://web.cse.ohio-state.edu/software/common/doc/index.html?components/naturalnumber/NaturalNumber.html

Answer 1

 NaturalNumber[] array = new NaturalNumber[4];
        NaturalNumber count = new NaturalNumber2(0);
        for (int i = 0; i < array.length; i++) {

            count = new NaturalNumber2(i);
            count.increment();
            array[i] = count;

Answer 2

**Initializing an array of NaturalNumbers with values 1 through 4**

你也可以这样做

int[] numbers = IntStream.range(1, 5).toArray();

Answer 3

You got 5,5,5,5 because you are using a boxed non-primitive type instead of a primitive.

So references to NaturalNumber count are to the location of an object. When you put that count into the array, you are putting the reference (four copies) and it contains the last value. Since you do an increment as the very last thing in the last go-through the loop, it points to a value 5 (but is not the value 5).

If you declared int count instead and used count++ since you can't call .increment () on a primitive, then you'd get the sequence 1, 2, 3, 4. The run-time engine would put the actual value of count at each time into the array.