Java Collections.max函数正在返回哈希代码（我想）

我相信我的Collections.max函数正在返回散列码，但老实说，我不完全确定到底发生了什么

我正在创建一个具有随机适用性值的树列表，实现一个比较器，然后试图找到下面的最高适用性值代码

public class Tree {
    public double suitability = Math.random();
    public int id;
    public static int count = 1;

    public Tree(double suitability, int id) {
        this.id = count;
        count++;    
    }

    public double getSuit() {
        return suitability;
    }

    public void setSuit(double suitability) {
        this.suitability = suitability;
    }

    public void measureSuit() {
           System.out.println("Tree number " + id + " has a suitability of " + suitability);
    }

}

class SuitComp implements Comparator<Tree> {

    @Override
    public int compare(Tree o1, Tree o2) {
        return Double.compare(o1.getSuit(), o2.getSuit());
    }   
} 


public class EmeraldRunner {

    public static void main(String[] args) {

        ArrayList<Tree> trees = new ArrayList<Tree>();

        Tree tree;

        int treeCount = 10;
        for (int i = 0; i < treeCount; i++) {
        tree = new Tree(i, i);

        trees.add(tree)

        Tree maxTree = Collections.max(trees, new SuitComp());

        System.out.println(maxTree);
        tree.measureSuit();

        }

    }

}

我的输出如下所示：

从洞穴里学习。Tree@60f32dde

1号树的适用性为0.6114866528786418

从洞穴里学习。Tree@60f32dde

2号树的适用性为0.28381422309266247

从洞穴里学习。Tree@3312b1dd

3号树的适用性为0.8441348268153896

从洞穴里学习。Tree@3312b1dd

4号树的适用性为0.6269071898386682

从洞穴里学习。Tree@3312b1dd

5号树的适用性为0.08717540188464434

从洞穴里学习。Tree@3312b1dd

6号树的适用性为0.3810530158434646

从洞穴里学习。Tree@3312b1dd

7号树的适用性为0.0938353693923476

从洞穴里学习。Tree@3312b1dd

树编号8的适用性为0.3656868216321937

从洞穴里学习。Tree@105b3e5d

9号树的适用性为0.9717207037612301

从洞穴里学习。Tree@105b3e5d

树编号10的适用性为0.44423960773823645

System.out.printlnmaxTree；调用maxTree上的toString。因为您没有重写它，所以它调用对象上的方法，该方法只输出完整的类名和一些附加信息

您需要实现toStringyourself以获得更可读的输出

public class Tree {
    public double suitability = Math.random();
    public int id;
    public static int count = 1;

    public Tree(double suitability, int id) {
        this.id = count;
        count++;
    }

    public double getSuit() {
        return suitability;
    }

    public void setSuit(double suitability) {
        this.suitability = suitability;
    }

    public void measureSuit() {
        System.out.println("Tree number " + id + " has a suitability of " + suitability);
    }

    @Override
    public String toString() {
        return "I am the tree with id " + id;
    }
}

---

你的问题是什么？为什么要获得此输出，或者如何获得对象的可读字符串表示形式？看到了，您正在打印一棵树，但尚未在树上实现toString。您看到的是对象提供给您的默认toString实现。您需要覆盖树中的公共字符串toString。我的问题是为什么它不打印列表中所有值的最大值？它是。最大值是Tree的一个对象，当您尝试打印一棵树时，您会得到所看到的结果。