Question

我在用Java泛型正确设置此模式时遇到问题，或者根本无法使用。我想有2个抽象类和一个普通的抽象类。每个子类都将自己的参数带到类中。从我的观点看来，我搞砸了泛型，但是我不知道在哪里。

public abstract class First {

private final long id;

First(Builder<?> builder) {
    this.id = builder.getId();
}


public static abstract class Builder<T extends Builder<T>> {

    @Getter long id;

    public abstract First build();

    public T setID(long id) {
        this.id = id;
        return (T)self();
    }

    protected abstract T self();
}

秒：

public abstract class Second extends First {

Second(Builder<?> builder) { 
    super(builder);
}


public static abstract class Builder<T extends Builder<T>> extends First.Builder {

    public T print() {
        System.out.println("hi");
        return (T) self();
    }

}
}

第三个：

public class Third extends Second {

private Third(Builder builder) {
    super(builder);
}

public static class Builder<T extends Builder<T>> extends Second.Builder {

    public Third build() {

        return new Third(this);
    }

    @Override
    protected Builder self() {
        return this;
    }
}

}

我的问题是，我可以打电话给

new Third.Builder()
            .print()
            .setID(1)
            .build();

但不是：

new Third.Builder()
            .setID(1)
            .print()
            .build();

java给了我

Error:(13, 17) java: cannot find symbol
symbol:   method print()
location: class blub.First.Builder

建筑模式的链式继承

0 个答案: