使用Collections.sort（object）比较Long值

为什么不实际在其中存放很长时间：

public class Tree implements Comparable<Tree> {    public long dist; //value is actually Long    public int compareTo(Tree o) {        return this.dist<o.dist?-1:    this.dist>o.dist?1:0;    }}

或先比较字符串的长度，然后再比较它们

public String dist; //value is actually Longpublic int compareTo(Tree o) {    if(this.dist.length()!=o.dist.length())          return this.dist.length()<o.dist.length()?-1:1;//assume the shorter string is a smaller value    else return this.dist.compareTo(o.dist);}