Java中方法作为参数传递的方式

@FunctionalInterface
public interface Consumer<T> {
    void accept(T t);
    default Consumer<T> andThen(Consumer<? super T> after) {
        Objects.requireNonNull(after);
        return (T t) -> { accept(t); after.accept(t); };
    }
}

void testConsumer(Integer id, Consumer consumer, String msg){
	consumer.accept(msg);
}
public static void main(String[] args){
	testConsumer(System.out::println, "consumer接口测试...");
	testConsumer(x -> {
			x = StringUtils.join(x,String.valueof(x).length());
			System.out.println(x);
		}, "consumer接口测试...")
}
#   输出结果
接口测试...
接口测试...15

/**传入一个Consumer类型的参数，
	 *他的泛型类型，
	 *跟本接口是一致的T，先做本接口的accept操作，
	 *然后在做传入的Consumer类型的参数的accept操作
	*/
    default Consumer<T> andThen(Consumer<? super T> after) {
        Objects.requireNonNull(after);
        return (T t) -> { accept(t); after.accept(t); };
    }

public class TestClass {
    interface TestFunction<T>{
        boolean getBooleanValue(T t);
    }
    static class Student{
        String name;
        Double score;
        Student(String name, Double score) {
            this.name = name;
            this.score = score;
        }
        Double getScore() {
            return score;
        }
    }
    static <T> void printMsg(T obj, TestFunction<T> function){
        if(function.getBooleanValue(obj)){
            System.out.println("result is true");
        }else{
            System.out.println("result is false");
        }
    }
    public static void main(String[] args) {
        printMsg(new Student("张三",92.5),x->{
            return x.getScore().compareTo(90d) > 0;
        });
        printMsg(new Student("张三",80.5),x->{
            return x.getScore().compareTo(90d) > 0;
        });
    }
}
# 输出结果
result is true
result is false

/**
 * @Author HE LONG CAN
 * @Description TODO
 * @Date 2022-06-26 12:21:06
 */
@FunctionalInterface
public interface Functional {
    void run();
}
/**
 * @Author HE LONG CAN
 * @Description TODO
 * @Date 2022-06-26 12:21:22
 */
public class Work {
    public static void doSome(Functional functional) {
        System.out.println("我要开始干活了");
        System.out.println("我板了一块砖");
        System.out.println("接下来是老板安排的任务...");
        functional.run();
        System.out.println("活干完了");
    }
}
/**
 * @Author HE LONG CAN
 * @Description TODO
 * @Date 2022-06-26 12:22:28
 */
public class Main {
    public static void main(String[] args) {
        Work.doSome(() -> {
            System.out.println("老板让我写报告");
            System.out.println("写报告中....");
        });
    }
}