java - 如何将方法分配为属性以便以后在任何兼容的对象上使用它？

Question

我正在尝试在T实现Menuable接口的任意类型上创建通用菜单：

public interface Procedure {
    void invoke();
}

public class Menu<T extends Menuable> implements Menuable {
    List<T> items; //The items of the menu
    List<String> itemsDisplay; //A list of String specifying how to display each of the above items
    Procedure procedure; //A method to be performed on the elements of items

    public Menu(List<T> items, List<String> itemsDisplay) {
        this.items = items;
        this.itemsDisplay = itemsDisplay;
    }

    //Returns a String display of the menu
    //Each item is numbered and displayed as specified by the list itemsDisplay
    public String menuDisplay() {

        String s = "";
        
        int i;
        for (i = 1; i <= this.itemsDisplay.size(); i++) {
            s = s + i + "\t" + this.itemsDisplay.get(i-1) + "\n";
        }
  
    return s;
    }
    ...
}

菜单将打印在终端上，当用户选择一个项目时，我希望菜单能够对该项目执行任何实例方法。基本上，这是我想做的：

public Menu(List<T> items, List<String> itemsDisplay, Procedure procedure) {
    this.items = items;
    this.itemsDisplay = itemsDisplay;
    Here I would like to assign a method to this.procedure for later use,
    but without specifying on which object to use it yet.
}

public void waitForAction() throws IOException {
        
    //Display the menu to the user
    System.out.println(this.menuDisplay());
    
    BufferedReader inputs = new BufferedReader(new InputStreamReader(System.in));

    int choice = 0;
    //Read inputs until the user enters a valid choice
    while(!(1 <= choice && choice <= this.items.size())) {

        try {
            choice = Integer.parseInt(inputs.readLine());
        } catch(NumberFormatException e) {
        }
    }

    //The item selected is at index (choice - 1) in the list this.items
    Here I would like to use my method on this.items.get(choice - 1).
}

我对使用方法作为变量/参数的想法很陌生，但我不知道该怎么做。我听说过 Java 中的 lambda 表达式和方法引用，但据我了解，在使用它们时，您必须同时指定要使用的方法及其实例/参数，这很尴尬。我错过了什么吗？

标签： javagenericsmethod-reference