《Cracking the Coding Interview》——第14章：Java——题目4

2014-04-26 19:02

题目：解释下C++里模板和java里泛型的区别？

解法：我很少用java，属于连语法都不过关的程度。所以这个题还真没法详细答，查了些资料以后写了以下几点。

代码：

 // 14.4 tell me about the differences between C++ template and java generics.
 // Answer:
 //    1. C++ template can be used on built-in type and user-defined types, java generics can only be used on classes. Integer for int, Double for double.
 //    2. java generics can put some restrictions on the <T>, such as <T extends superclass>, whereas this is not practical in C++.
 //    3. You may use downcast instead of generics, but generics enhance the resuability of code, so is template in C++.
 import java.util.Vector;

 public class TestJava<T> {
     public T data;

     public TestJava(T data) {
         // TODO Auto-generated constructor stub
         this.data = data;
     }

     String getType() {
         return this.data.getClass().getName();
     }

     public static void main(String[] args) {
         Vector<Integer> v = new Vector<Integer>();
         v.add(2);
         v.add(1);

         TestJava<Vector<Integer>> testJava = new TestJava<Vector<Integer>>(v);
         System.out.println(testJava.getType());
         System.out.println(v);
     }
 }