这个问题在这里已有答案：
我试图通过使用java中的比较来理解我的老师想要从这个练习中得到什么。
我不确定我需要做什么。有人能给我一个良好的开端吗？
public class BookTag implements Comparable {
private String left;
private int mid;
private String right;
public BookTag(String left, int mid, String right) {
check(left, mid, right);
this.left = left.toUpperCase();
this.mid = mid;
this.right = right.toUpperCase();
}
@Override
public int compareTo(Object arg) {
/*
* Booktags are sorted as follows: - first go booktags with lowest left
* attribute. If left attributes cannot discriminate... - ... first go booktags
* with the lowest mid attribute. If mid cannot discriminate... - ... first go
* booktags with HIGHEST right attribute.
*/
/* COMPLETE */
BookTag tag = (BookTag) arg;
return this.left.compareTo(tag.compareTo(left));
}
}
我需要在这里比较什么价值之王？
对象不能像原始类型那样自然地进行比较，因此您必须自己提供一些排序。一种方法是实现Comparable<T>接口。
public class BookTag implements Comparable<BookTag> {
//compares this tag with another: 0 indicates equality, 1 means this is
//bigger, -1 means the other is bigger
public int compareTo(BookTag other) {
int c = this.left.compareTo(other.left); //string implements this
if(c != 0) {
return -c; //if the other's left is "smaller", this object is "bigger"
}
c = this.mid - other.mid;
if(c != 0) {
return -c; //if the other's mid is "smaller", this object is "bigger"
}
c = this.right.compareTo(other.right);
if(c != 0) {
return c; //if the other's right is "bigger", this object is "bigger"
}
return 0; //if we get here, then all values are equal, and so are the objects
}
}
我实现了Comparable<BookTag>而不是原始的Comparable更简单的代码。
BookTag other = ((BookTag)o); // cast it
int leftcompare = this.left.compareTo(other.getLeft());
int midCompare = this.mid - other.getMid();
// careful with the right compare as the highest goes first
int rightCompare = this.right.compareTo(other.getRight());
// if , then, else statement to fill your teacher's requirements
// negative number means that this book tag is higher on the compare list
// 0 means cannot discriminate (move to the next field left -> mid -> right
// positive number means the other BookTag is higher on the list
而且我不知道这一个，但也许你只能权衡价值而不是if-then-else。玩得开心 ：）