Java tricky question

Java tricky question

原文：4 out of 5 Java developers failed to solve this question

1. The toughest question of the Java deathmatch

正确答案：Compliation fails because no SQLException is thrown

关于java泛型类型擦除的问题。

2. toString(), or not toString(), that is the question

类没有实现toString的小陷阱

正确答案：None of the above

3. Google Guava Sets

正确答案：Potential out of memory

4. Double brace initialization, lol wut?!

正确答案：Potential null access

参考Double Brace Initialization，集合{{}}的形式相当于匿名内部类，NAMES.add的时候还没实例化完成。。

正确的写法：

private static final List NAMES = new ArrayList(){{
    add("Hello");
    this.add("World");
    System.out.println(this); //这里用NAMES的话是null
}};

5. The curious case of the map at runtime

正确答案：[] true

Bonus: And the easiest question is…

正确答案：C