java函数式编程之UnaryOperator

描述：一元运算，接受一个T类型参数，输出一个与入参一模一样的值
源码：

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;
    }
}

测试代码：

@Test
    public void test(){
        super.print(UnaryOperator.identity().apply(1));//输出1
        super.print(UnaryOperator.identity().apply(false));//输出false
        super.print(UnaryOperator.identity().apply("string"));//输出string
    }