因为任何类,默认都是已经实现了equals(Object obj)的。 Java中的一切类都是继承于java.lang.Object,在Object.java中实现了equals(Object obj)函数;所以,其它所有的类也相当于都实现了该函数。 (02) int compare(T o1, T o2) 是“比较o1和o2的大小”。返回“负数”,意味着“o1比o2小”;返回“零”,意味着...
If any class implements Comparable interface in Java then collection of that object either List or Array can be sorted automatically by using Collections.sort() or Arrays.sort() method and objects will be sorted based on there natural order defined by CompareTo method. To summarize, if sorting ...
The sorting order is decided by the return value of thecompareTo()method.TheInteger.compare(x, y)returns -1 ifxis less thany, 0 if they’re equal, and 1 otherwise. The method returns a number indicating whether the object being compared is less than, equal to, or greater than the obje...
* can use this method because we have implemented the * Comparable interface in our user defined class Author */Collections.sort(al);for(Authorstr:al){System.out.println(str.firstName+" "+str.lastName+" "+"Book: "+str.bookName);}}} Java Copy 输出: DeborahHopkinsonBook:SkyBoysNaloHopki...
Comparable : This interface has one method compareTo. Class whose objects to be sorted must implement this Comparable interface. In this case there is one form or way of sorting, e.g. We can sort players by age, so if we want to sort them by ranking or by name, in this case we ha...
* this method can take advantage of it: the method assumes that the * elements from index {@code lo}, inclusive, to {@code start}, * exclusive are already sorted. * * @param a the array in which a range is to be sorted * @param lo the index of the first element in the range...
java中Comparable的例子和用法 3.5 Comparable的用法 马克-to-win:前面讲过进入TreeSet的每个元素是都排了序的,如果被添加的元素是我们自己定义的,就需要告诉TreeSet排序的规则,这个规则就要在Comparable中定义。在下面的例子中, 当我们要往TreeSet中添加我们自己定义的类Worker对象时,就在compareTo中定义排序规则。
Exception in thread “main” java.lang.Error: Unresolved compilation problem: Bound mismatch: The generic method sort(List) of type Collections is not applicable for the arguments (ArrayList). The inferred type Student is not a valid substitute for the bounded parameter > at beginnersbook.com.Deta...
Java Comparator Comparator interfacecompare(Object o1, Object o2)method need to be implemented that takes two Object argument, it should be implemented in such a way that it returns negative int if the first argument is less than the second one and returns zero if they are equal and positive...
This interface imposes a total ordering on the objects of each class that implements it. This ordering is referred to as the class'scompareTomethod is referred to as itsnatural comparison method. public interfaceComparator<T> A comparison function, which imposes atotal orderingon some collection ...