hashmapdemo.java

java的书上例子

//例15-6. HashMapDemo.java
import java.util.*;
import java.io.*;
	
public class HashMapDemo {
	public static void main(String[] args) {
		HashMap hm = new HashMap();
		hm.put("1",new Integer(1));
		hm.put(new File("test.txt"),"2");
		hm.put(new Byte((byte)3),System.out);
		hm.put(null,"nothing");
		Set s = hm.keySet();
		Iterator i = s.iterator();
		while ( i.hasNext() ) {
			Object k = i.next();
			Object v = hm.get(k);
			System.out.print("  "+k+"="+v);
			if ( v instanceof PrintStream )
				((PrintStream)v).print("(I am a PrintStream!)");
		}
	}
}