问题描述
我遇到了一些代码，尽管有点阅读，但我还是很难理解。调用一个方法，该方法接受两个args，其中一个是Runnable。而不是传递一个Runnable对象虽然有一个lambda。
I've come across some code which I'm struggling to understand despite a bit of reading. There is a call to a method which takes in two args, one of which is a Runnable. Rather than passing in a Runnable object though there is a lambda.
例如：
public class LambdaTest {
private final Lock lock = new ReentrantLock();
@Test
public void createRunnableFromLambda() {
Locker.runLocked(lock, () -> {
System.out.println("hello world");
});
}
public static class Locker {
public static void runLocked(Lock lock, Runnable block) {
lock.lock();
try {
block.run();
} finally {
lock.unlock();
}
}
}
}
所以我的问题是，你能解释一下吗？如何从lambda创建Runnable，还有人可以解释语法（） - > {}。具体来说，（）括号是什么意思？
So my question is, can you explain how a Runnable is created from the lambda, and also please could someone explain the syntax () -> {}. Specifically, what do the () brackets mean?
谢谢。
推荐答案
Lambda可以在任何需要功能接口的地方使用。
功能接口是具有单个抽象方法的任何接口。
A Lambda can be used in any place where a functional interface is required.A functional interface is any interface with a single abstract method.
在这种情况下使用的lambda语法是（参数） - > ; {blockOfCodeOrExpression} 。在单个参数的情况下可以省略括号，并且在单个命令或表达式的情况下可以省略括号。
The lambda syntax used in this case is (arguments) -> {blockOfCodeOrExpression}. The parenthesis can be omitted in the case of a single argument, and the braces can be omitted in the case of a single command or expression.
换句话说，（） - > System.out.println（hello world）; 相当于*到
new Runnable(){
@Override
public void run(){
System.out.println("Hello world one!");
}
};
（我很确定它不是字节码等价的，但在功能方面是等价的）
(I'm pretty sure that it is not bytecode-equivalent, but is equivalent in terms of functionality)
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