泛型类声明看起来像非泛型类声明，不同之处在于，类名后跟一个类型参数部分，通用类的类型参数部分可以具有一个或多个用逗号分隔的类型参数。
Generic Classes - 语法
public class Box<T> { private T t; }
Where
Box - Box是一个通用类。
T - 传递给通用类的参数。它可以是任何对象。
t - 通用类型T的实例化。
T是传递给泛型类Box的类型参数，在创建Box对象时应传递T。使用您选择的任何编辑器创建以下Java程序。
package com.learnfk;
public class GenericsTester {
public static void main(String[] args) {
Box<Integer> integerBox=new Box<Integer>();
Box<String> stringBox=new Box<String>();
integerBox</span><span class="pun">.</span><span class="kwd">add</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">Integer</span><span class="pun">(</span><span class="lit">10</span><span class="pun">));</span><span class="pln">
stringBox</span><span class="pun">.</span><span class="kwd">add</span><span class="pun">(</span><span class="kwd">new</span><span class="pln"> </span><span class="typ">String</span><span class="pun">(</span><span class="str">"Hello World"</span><span class="pun">));</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">printf</span><span class="pun">(</span><span class="str">"Integer Value :%d\n"</span><span class="pun">,</span><span class="pln"> integerBox</span><span class="pun">.</span><span class="kwd">get</span><span class="pun">());</span><span class="pln">
</span><span class="typ">System</span><span class="pun">.</span><span class="kwd">out</span><span class="pun">.</span><span class="pln">printf</span><span class="pun">(</span><span class="str">"String Value :%s\n"</span><span class="pun">,</span><span class="pln"> stringBox</span><span class="pun">.</span><span class="kwd">get</span><span class="pun">());</span><span class="pln">
}
}
class Box<T> {
private T t;
public void add(T t) {
this.t=t;
}
public T get() {
return t;
}
}
这将产生以下输出。
Integer Value :10 String Value :Hello World
