本人编写了一个统计单词频率的程序:
import java.util.HashMap;
import java.util.Map;
public class TongJi {
private static final Integer ONE=new Integer(1);public static void main(String[] args) {
Map m=new HashMap();
for(int i=0;i<args.length;i++)
{
Integer freq=(Integer)m.get(args[i]);
m.put(args[i], (freq==null?ONE:new Integer(freq.intValue()+1)));
}
System.out.println(m);
}}编译后提示:
Note: E:\design--houq\TongJi.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.请问是怎么回事啊?
import java.util.HashMap;
import java.util.Map;
public class TongJi {
private static final Integer ONE=new Integer(1);public static void main(String[] args) {
Map m=new HashMap();
for(int i=0;i<args.length;i++)
{
Integer freq=(Integer)m.get(args[i]);
m.put(args[i], (freq==null?ONE:new Integer(freq.intValue()+1)));
}
System.out.println(m);
}}编译后提示:
Note: E:\design--houq\TongJi.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.请问是怎么回事啊?
jdk1.5,泛型
Map<Integer,Integer> m=new HashMap<Integer,Integer>();//指定类型
改成Map<String,int> m = new HashMap<String,int>();试试
Map<String,Integer> m=new HashMap<String,Integer>();