用Java打印数组

Question

我正在编写一个方法来打印它传递的每个Object.通过调用Object.toString()对象的方法可以正常工作,但不适用于数组.我可以通过该Object.getClass().isArray()方法找出它是否是一个数组,但我不知道如何投射它.

int[] a;
Integer[] b;

Object aObject = a;
Object bObject = b;

// this wouldn't work
System.out.println(Arrays.toString(aObject));
System.out.println(Arrays.toString(bObject));

Answer 1

如果您不知道类型,您可以将对象强制转换Object[]并打印出来(在确定它确实是一个数组并且可以转换为Object[])之后.如果它不是一个实例Object[]然后使用反射创建Object[]第一个然后打印:

private void printAnyArray(Object aObject) {
    if (aObject.getClass().isArray()) {
        if (aObject instanceof Object[]) // can we cast to Object[]
            System.out.println(Arrays.toString((Object[]) aObject));
        else {  // we can't cast to Object[] - case of primitive arrays
            int length = Array.getLength(aObject);
            Object[] objArr = new Object[length];
            for (int i=0; i<length; i++)
                objArr[i] =  Array.get(aObject, i);
            System.out.println(Arrays.toString(objArr));
        }
    }
}

测试:

printAnyArray(new int[]{1, 4, 9, 16, 25});
printAnyArray(new String[]{"foo", "bar", "baz"});

OUTPUT:

[1, 4, 9, 16, 25]
[foo, bar, baz]