关于匿名内部类

最新推荐文章于 2023-01-17 03:20:00 发布

转载最新推荐文章于 2023-01-17 03:20:00 发布 · 834 阅读

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#class #construction #variables #access #string #c

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本文探讨了Java中静态内部类的实例化方式，解释了如何从外部包构造静态内部类的实例，并澄清了一些常见误解。

12. Which statement is true?

A. An anonymous inner class may be declared as final
B. An anonymous inner class can be declared as private
C. An anonymous inner class can implement multiple interfaces
D. An anonymous inner class can access final variables in any enclosing scope
E. Construction of an instance of a static inner class requires an instance of the enclosing outer class.
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13. Given:

1. package foo;
2.
3. public class Outer (
4. public static class Inner (
5. )
6. )

Which statement is true?

A. An instance of the Inner class can be constructed with “new Outer.Inner ()”
B. An instance of the inner class cannot be constructed outside of package foo
C. An instance of the inner class can only be constructed from within the outer class
D. From within the package bar, an instance of the inner class can be constructed with “new inner()”
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这是一个static inner class.所以A是正确的。
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/**
A. An instance of the Inner class can be constructed with “new Outer.Inner ()”
B. An instance of the inner class cannot be constructed outside of package foo
C. An instance of the inner class can only be constructed from within the outer class
D. From within the package bar, an instance of the inner class can be constructed with “new inner()”
*/
package foo;
public class Outer
{
public static class Inner
{
public void writeSt()
{
System.out.println("Hello");
}
}
}

class TryInner
{
public TryInner()
{
new Outer.Inner(); //-------------A is OK!!!! and C is wrong.
}
}
***************
/**
A. An instance of the Inner class can be constructed with “new Outer.Inner ()”
B. An instance of the inner class cannot be constructed outside of package foo
C. An instance of the inner class can only be constructed from within the outer class
D. From within the package bar, an instance of the inner class can be constructed with “new inner()”
*/
package bar;
class TryPack
{
public static void main(String[] args)
{
System.out.println("Hello World!");
//new Inner(); -----------This line is wrong so D is wrong;
new foo.Outer.Inner(); // You should write like this. and B is wrong
}
}
************************The Answer is A