有可能???

Question

我想覆盖已经分配给变量的类的方法例如：

inventory = new Inventory( );

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

inventory
{
    @Override ...
}

有可能???

Answer 1

也许您会想到这样的事情（而不是null - 如果您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();

显示了这一点：

strategy is empty
strategy is now something different

有关更详细的版本，您可以查看strategy pattern。

Answer 2

这里的作文肯定会有所帮助。而不是重写一个方法来改变Inventory的行为，而不是传递方法：

class Inventory {
    private MyMethod method;

    public void setMethod(MyMethod method) {
        this.method = method;
    }

    public void doSomething() {
        method.doSomething();
    }
}

interface MyMethod {
    void doSomething();
}

您现在可以通过MyMethod：

切换setMethod的实施

Inventory inv = new Inventory();
//...

inv.setMethod(() -> {
    //write method here
});

如果您不使用Java 8，则必须继承MyMethod：

inv.setMethod(new MyMethod() {
    public void doSomething() {

    }
});

从指定的类重写方法

有可能???

2 个答案: