为什么实现 Comparable
接口(interface)比仅仅定义我自己的 compareTo()
方法更有好处?
另一件事,java.util.Arrays.sort(Object[] o)
方法如何与Comparable
接口(interface)相关,这样我就必须实现Comparable接口(interface)能够使用 Arrays.sort(Object[] o) 方法吗?
最佳答案
Why is it beneficial to implement the Comparable interface instead of just defining my own compareTo method?
您可以定义自己的方法,但所有需要比较的类都必须知道它。 Java api中有Comparable用于此目的,并且所有人都知道它。可比较接口(interface)是许多类的父类(super class)型,无论其来源如何。因此,它在所有主要框架中都得到普遍使用。
Another thing, how does the java.util.Arrays.sort(Object[] o) method relate to the Comparable interface such that I HAVE to implement the Comparable interface to be able to use the Arrays.sort(Object[] o) method?
Arrays.sort()
方法内部调用 Comparable
类的 compareTo()
方法对内容进行排序。
查看Arrays.sort()
的源码,委托(delegate)方法使用 Comparabble#compareTo()
方法
private static void mergeSort(Object[] src,
Object[] dest,
int low,
int high,
int off) {
int length = high - low;
// Insertion sort on smallest arrays
if (length < INSERTIONSORT_THRESHOLD) {
for (int i=low; i<high; i++)
for (int j=i; j>low &&
((Comparable) dest[j-1]).compareTo(dest[j])>0; j--)
swap(dest, j, j-1);
return;
}
// Recursively sort halves of dest into src
int destLow = low;
int destHigh = high;
low += off;
high += off;
int mid = (low + high) >>> 1;
mergeSort(dest, src, low, mid, -off);
mergeSort(dest, src, mid, high, -off);
// If list is already sorted, just copy from src to dest. This is an
// optimization that results in faster sorts for nearly ordered lists.
if (((Comparable)src[mid-1]).compareTo(src[mid]) <= 0) {
System.arraycopy(src, low, dest, destLow, length);
return;
}
// Merge sorted halves (now in src) into dest
for(int i = destLow, p = low, q = mid; i < destHigh; i++) {
if (q >= high || p < mid && ((Comparable)src[p]).compareTo(src[q])<=0)
dest[i] = src[p++];
else
dest[i] = src[q++];
}
}
关于java - 类似的接口(interface),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/22091880/