java - 覆盖指定类中的方法

Question

我想重写已分配给变量的类中的方法。
例如:

inventory = new Inventory( );

/* Some code here that changes how inventory
must behave or whatever */

inventory
{
    @Override ...
}

可能吗？？？

Answer 1

也许你会想到这样的东西(而不是 null - 如果你可以实现默认策略以使其更干净):

public interface Strategy {

    public void doSomething();

}

public class Inventory {

    Strategy strategy;

    public Inventory() {
        // ...
    }

    public void doSomething() {
        if (strategy == null) {
            System.out.println("strategy is empty");
        } else {
            strategy.doSomething();
        }
    }

    public Strategy getStrategy() {
        return strategy;
    }

    public void setStrategy(Strategy strategy) {
        this.strategy = strategy;
    }

}

然后这个

    Inventory inventory = new Inventory();
    inventory.doSomething();
    inventory.setStrategy(new Strategy() {

        @Override
        public void doSomething() {
            System.out.println("strategy is now something different");
        }

    });
    inventory.doSomething();

显示:

strategy is empty
strategy is now something different

要获得更详细的版本，您可以查看 strategy pattern .