“->”在java中是什么意思[duplicate]

Question

/*
 * Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
 */
package java.util.function;

/**
 * Represents an operation on a single operand that produces a result of the
 * same type as its operand.  This is a specialization of {@code Function} for
 * the case where the operand and result are of the same type.
 *
 * <p>This is a <a href="package-summary.html">functional interface</a>
 * whose functional method is {@link #apply(Object)}.
 *
 * @param <T> the type of the operand and result of the operator
 *
 * @see Function
 * @since 1.8
 */
@FunctionalInterface
public interface UnaryOperator<T> extends Function<T, T> {

    /**
     * Returns a unary operator that always returns its input argument.
     *
     * @param <T> the type of the input and output of the operator
     * @return a unary operator that always returns its input argument
     */
    static <T> UnaryOperator<T> identity() {
        return t -> t;
    }
}

我发现这是->在Java中的意思，但我不适合我

------------更新-------------------------------------

java -version
java version "1.8.0_66"
Java(TM) SE Runtime Environment (build 1.8.0_66-b18)
Java HotSpot(TM) 64-Bit Server VM (build 25.66-b18, mixed mode)

Answer 1

您看到的是一个Lambda表达式，这是在Java8中添加的一个新特性。

关于lambdas要说的太多了，所以要全部放在这里，但简而言之，这是一种非常简洁的方法，可以添加一个只包含单个方法的匿名类。

您提到的方法在功能上相当于：

static <T> UnaryOperator<T> identity() {
    return new UnaryOperator<T>{
       public T apply(T parameter){
         return parameter;
       }
    }
}