java - 通过id获取java对象

Question

我想要实现的是只用已知的 ID 来更新对象的值:

1. 如何获取具有相应 ID 的对象？
2. 以便我可以更新属性？

类森林

public class forest {
    public forestName;
    
    public forest(String forestName){
        this.forestName=forestName;
    }
    updateTreeName(int id, String Name){
        // Here I need to update the name of the tree with that specific ID
    }

    public static void main(String[] args) {
        forest greenforest = new forest();
        // create some tree's in the greenforest.
        greenforest.updateTreeName(4, "red leafe");
    }
}

类树

public class tree {
    public String treeName;
    public int id;
    public tree(int id, String treeName){
        this.treeName=treeName;
        this.id=id;
    }
}

Answer 1

使用HashMap来保存对象。然后使用 get 方法获取具有给定 id 的对象。

public class Forest {
    public String forestName;

    HashMap<Integer, Tree> trees = new HashMap<>();

    public Forest(String forestName){
        this.forestName=forestName;

        //initialize trees
        trees.put(4, new Tree(4, "redleaef"));
    }

    public void updateTreeName(int id, String Name){
        trees.get(id).treeName = Name;
    }

    public static void main(String[] args) {
        Forest greenforest = new Forest("name");
        // create some tree's in the greenforest.
        greenforest.updateTreeName(4, "red leafe");
    }
}