getter和setter方法​​阵列 [英] Getters and setters for arrays

问题描述

我对getter和setter方法​​阵列的几个问题。假设我们有这样的一类，这使得数组的拷贝在其构造：

I have a few questions about getters and setters for arrays. Suppose we have a class like this, which makes a private copy of an array in its constructor:

import java.util.Arrays;

public class Foo
{
    private int[] array;

    public Foo(int[] array) {
        this.array = Arrays.copyOf(array, array.length);
    }
}

我们希望才可以访问/通过getter和setter突变的数组。如果我们有一个getter，看起来像这样：

We want the array to only be accessed/mutated via the getters and setters. If we have a getter that looks like this:

public int[] getArray() {
    return array;
}

它作为我们返回一个参考，允许用户直接修改数组的元素击败吸气的目的。例如。

it defeats the purpose of the getter as we're returning a reference that allows the user to directly modify the elements of the array. e.g.

Foo foo = new Foo(someArray);
...
int[] bar = foo.getArray();
bar[0] = 123; // Now foo.array[0] = 123 and we haven't used a setter!

所以presumably我们需要的是这样的：

So presumably we need something like this:

public int getElement(int index) {
    return array[index];
}

同样，对于制定者。但是，如果我们每个元素的基础上做的事情，我们也将需要提供越来越长的方法：

Similarly for setters. But if we're doing things on a per-element basis, we're also going to need to provide a means of getting the length:

public int getArrayLength() {
    return array.length;
}

这已经是一个一维数组有些凌乱，但说我们有一个多维数组来代替：

This is already a little messy for a 1-dimensional array, but say we have a multidimensional array instead:

import java.util.Arrays;

public class Foo
{
    private int[][][] array;

    public Foo(int[][][] array) {
        // Code for making a deep copy here
    }

    public int getElement(int i, int j, int k) {
        return array[i][j][k];
    }

    public void setElement(int i, int j, int k, int value) {
        array[i][j][k] = value;
    }

    public int getArrayLength() {
        return array.length;
    }

    public int getArrayLength(int i) {
        return array[i].length;
    }

    public int getArrayLength(int i, int j) {
        return array[i][j].length;
    }
}

这是这样一个简单的任务很多code，而且更重要的是它是一个烂摊子实际使用。难道我们真的有这样的事情结束了，还是有更好的方式来做到这一点？我看了所有的地方和似乎没有成为一个标准做法这一点。

This is a lot of code for such a trivial task, and more importantly it's a mess to actually use. Do we really have to end up with something like this, or is there a better way to do it? I've looked all over the place and there doesn't seem to be a "standard practice" for this.

推荐答案

一个多维数组也是一维数组： INT [A] [B] [C] 真的只是 INT [A * b * C] ，所以这个问题归结到，你如何提供安全的访问？只要是这样的：

A multi-dimensional array is also a 1-dimensional array: int[a][b][c] is really just int[a*b*c], so the problem boils down to, how do you provide access safely? Simply like this:

public class Foo {
    private int[] array;

    public Foo(int[] array) {
        this.array = Arrays.copyOf(array, array.length);
    }

    /** @return a copy of the array */
    public int[] getArray() {
        return Arrays.copyOf(array, array.length);
    }
}

这就是它。

呼叫者在阵列的安全拷贝，用于在全正常的方式阵列可以使用它。无需委托方法。

Callers have a safe copy of the array and can use it in the full normal way arrays are used. No need for delegator methods.

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