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JDK 1.5之Generics_MySQL

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Release: 2016-06-01 14:07:08
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JDK

  Generics 是JDK 1.5 一个最重要的特性,主要用来处理Collection。

  以下代码在JDK 1.5 调试通过。

  代码实例1: Demo.java

  package maoxiang.examples.jdk15.generics;
  import java.util.ArrayList;
  import java.util.Collection;
  import java.util.HashMap;
  import java.util.LinkedList;
  import java.util.List;
  import java.util.Map;

  /**
  * @author 毛翔
  *
  * 演示如何使用Generics 特性。代码来自于 Generics 教程:
  * http://java.sun.com/j2se/1.5/pdf/generics-tutorial.pdf
  *
  * Generics类似于C++中的模板。
  * 区别:
  * 1.
  * 2.
  */

  public class Demo {
  public static void main(String[] args) {}

  /**
  * 最简单的用法
  */

  public void Test1() {

  // 以前的用法
  //List myIntList = new LinkedList(); // 1
  //myIntList.add(new Integer(0)); // 2
  //Integer x = (Integer) myIntList.iterator().next(); // 3 需要强制转换
  // 1.5 的用法
  List myIntList = new LinkedList(); // 1’
  myIntList.add(new Integer(0)); //2’
  Integer x = myIntList.iterator().next(); // 3’
  }

  /**
  * 匿名字符的用法
  */

  public void Test2() {
  List list = new ArrayList();
  //通过匿名字符打印一个集合

  Wildcards(list);
  Wildcards1();
  /*
  * 如果 Wildcards2 定义为Wildcards2(List shapes)
  * 以下调用错误
  */
  Wildcards2(list);
  }

  public void Wildcards(Collection c) {
  // 以前的用法
  //Iterator i = c.iterator();
  //for (int k = 0; k   //
  log(i.next());
   /

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