ArrayList参数化，arraylist参数

ArrayList参数化，arraylist参数

import java.util.ArrayList; public class Print { public static void main(String[] args) { //参数化必须加上<String> ArrayList<String> stringList2 = new ArrayList<String>(); stringList2.add("Java 5.0 is good!"); //经过参数化后以下语句就不必写成这样子了 //String s2 = (String)stringList2.get(0); String s2 = stringList2.get(0); System.out.println(s2.toUpperCase()); //非参数化(会提示要求) ArrayList stringList3 = new ArrayList(); stringList3.add("No Parameterize."); //每次调用都要强类型转换,这将会很麻烦. String s3= (String)stringList3.get(0); System.out.println(s3.toUpperCase()); } }

 

输出结果:

JAVA 5.0 IS GOOD!
NO PARAMETERIZE.