Java 相当于 Cocoa 委托Objective-C 非正式协议

Java 相当于 Cocoa 委托/Objective-C 非正式协议？

java
// 委托者接口
interface Delegate {
    void doTask();
}
// 代理者类
class DelegateImpl implements Delegate {
    @Override
    public void doTask() {
        System.out.println("代理者完成任务");
    }
}
// 委托者类
class Delegator {
    private Delegate delegate;
    public void setDelegate(Delegate delegate) {
        this.delegate = delegate;
    }
    public void doTask() {
        if (delegate != null) {
            delegate.doTask();
        }
    }
}
// 使用委托模式
public class DelegatePatternExample {
    public static void main(String[] args) {
        Delegator delegator = new Delegator();
        Delegate delegate = new DelegateImpl();
        delegator.setDelegate(delegate);
        delegator.doTask();
    }
}

objective-c
// 非正式协议
@protocol Delegate
- (void)doTask;
@end
// 代理者类
@interface DelegateImpl : NSObject 
@end
@implementation DelegateImpl
- (void)doTask {
    NSLog(@"代理者完成任务");
}
@end
// 委托者类
@interface Delegator : NSObject
@property (nonatomic, strong) id delegate;
- (void)doTask;
@end
@implementation Delegator
- (void)doTask {
    if (self.delegate != nil) {
        [self.delegate doTask];
    }
}
@end
// 使用非正式协议
int main() {
    Delegator *delegator = [[Delegator alloc] init];
    DelegateImpl *delegate = [[DelegateImpl alloc] init];
    delegator.delegate = delegate;
    [delegator doTask];
    return 0;
}