在 Java 中创建一个数组并将其作为参数传递

发布于 2024-12-06 13:21:00 字数 460 浏览 1 评论 0原文

有没有办法创建对象数组作为构造函数或方法的一部分？我真的不知道如何表达，所以我举了一个例子。我有一个枚举，其中一个字段是一组数字。这是我尝试过的：

public enum KeyboardStuff {

    QWERTY(1, {0.5f, 1.3f, 23.1f}, 6);
    DVORAK(5, {0.1f, 0.2f, 4.3f, 1.1f}, 91);
    CHEROKEE(2, {22.0f}, 11);

    private int number, thingy;
    private float[] theArray;

    private KeyboardStuff(int i, float[] anArray, int j) {
        // do things
    }

}

编译器说括号 { } 无效，应该删除。有没有一种方法可以将数组作为参数传递而无需事先创建对象数组？

原文

Is there a way to create an array of objects as part of a constructor or method? I'm really not sure how to word this, so I've included an example. I have an enum, and one of the fields is an array of numbers. Here is what I tried:

public enum KeyboardStuff {

    QWERTY(1, {0.5f, 1.3f, 23.1f}, 6);
    DVORAK(5, {0.1f, 0.2f, 4.3f, 1.1f}, 91);
    CHEROKEE(2, {22.0f}, 11);

    private int number, thingy;
    private float[] theArray;

    private KeyboardStuff(int i, float[] anArray, int j) {
        // do things
    }

}

The compiler says that the brackets { } are invalid and should be removed. Is there a way I can pass an array as an argument without creating an array of objects beforehand?

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假扮的天使 2024-12-13 13:21:00

您可以尝试使用new float[] { ... }。

public enum KeyboardStuff {

    QWERTY(1, new float[] {0.5f, 1.3f, 23.1f}, 6);
    DVORAK(5, new float[] {0.1f, 0.2f, 4.3f, 1.1f}, 91);
    CHEROKEE(2, new float[] {22.0f}, 11);

    private int number, thingy;
    private float[] theArray;

    private KeyboardStuff(int i, float[] anArray, int j) {
        // do things
    }

}

You can try with new float[] { ... }.

public enum KeyboardStuff {

    QWERTY(1, new float[] {0.5f, 1.3f, 23.1f}, 6);
    DVORAK(5, new float[] {0.1f, 0.2f, 4.3f, 1.1f}, 91);
    CHEROKEE(2, new float[] {22.0f}, 11);

    private int number, thingy;
    private float[] theArray;

    private KeyboardStuff(int i, float[] anArray, int j) {
        // do things
    }

}

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天赋异禀 2024-12-13 13:21:00

按照 @Dave 的建议，我将使用 vararg

QWERTY(1, 6, 0.5, 1.3, 23.1);
DVORAK(5, 91, 0.1, 0.2, 4.3, 1.1);
CHEROKEE(2, 11, 22.0);

private final int number, thingy;
private final double[] theArray;

private KeyboardStuff(int number, int thingy, double... theArray) {
    // do things
}

使用 float 比使用 double 更好的情况很少见。 double 的舍入误差较小，仅多使用 4 个字节。

Following @Dave's suggest I would use a vararg

QWERTY(1, 6, 0.5, 1.3, 23.1);
DVORAK(5, 91, 0.1, 0.2, 4.3, 1.1);
CHEROKEE(2, 11, 22.0);

private final int number, thingy;
private final double[] theArray;

private KeyboardStuff(int number, int thingy, double... theArray) {
    // do things
}

It is pretty rare that using a float is better than using a double. double has less rounding error and only uses 4 more bytes.

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清眉祭 2024-12-13 13:21:00

有没有一种方法可以在不创建数组的情况下传递数组？

不，但是您可以使用 varargs 来制作它大部分是不可见的，尽管最后的 int 可能需要移动。

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不美如何 2024-12-13 13:21:00

如果可以选择使用列表而不是数组，则 Java 的未来版本可能会开始支持“集合文字” ' 语法不幸的是似乎没有进入 Java 8：

public enum KeyboardStuff {

    QWERTY(1, [0.5f, 1.3f, 23.1f], 6);
    DVORAK(5, [0.1f, 0.2f, 4.3f, 1.1f], 91);
    CHEROKEE(2, [22.0f], 11);

    private int number, thingy;
    private List<Float> values;

    private KeyboardStuff(int i, List<Float> values, int j) {
        // do things
    }

}

If using Lists's instead of arrays is an option, future versions of Java might start supporting a 'collection literals' syntax which unfortunately doesn't seem to have made it into Java 8:

public enum KeyboardStuff {

    QWERTY(1, [0.5f, 1.3f, 23.1f], 6);
    DVORAK(5, [0.1f, 0.2f, 4.3f, 1.1f], 91);
    CHEROKEE(2, [22.0f], 11);

    private int number, thingy;
    private List<Float> values;

    private KeyboardStuff(int i, List<Float> values, int j) {
        // do things
    }

}

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