keySet()与entrySet()
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- import java.util.Calendar;
- import java.util.Date;
- import java.util.HashMap;
- import java.util.Iterator;
- import java.util.Map.Entry;
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- public class HashMapTest
- {
- public static void main(String[] args)
- {
- HashMap<String,String> kmap = new HashMap<String,String>();
- HashMap<String, String> emap = new HashMap<String, String>();
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- for (int i = 0; i < 1000; i++)
- {
- kmap.put(""+i, "YL");
- }
- for (int i = 0; i < 1000; i++)
- {
- emap.put(""+i, "ZT");
- }
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- long stimes = System.currentTimeMillis();
- long ctimes = Calendar.getInstance().getTimeInMillis();
- long dtimes = new Date().getTime();
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- System.out.println(stimes+" "+ctimes+" "+dtimes);
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- Iterator<String> ktor = kmap.keySet().iterator();
- while(ktor.hasNext())
- {
- System.out.println(ktor.next());
- }
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- long stimes1 = System.currentTimeMillis();
- long ctimes1 = Calendar.getInstance().getTimeInMillis();
- long dtimes1 = new Date().getTime();
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- System.out.println((stimes1-stimes)+" "+(ctimes1-ctimes)+" "+(dtimes1-dtimes));
- System.out.println(stimes1+" "+ctimes1+" "+dtimes1);
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- Iterator<Entry<String, String>> itor = emap.entrySet().iterator();
- while(itor.hasNext())
- {
- Entry<String, String> e = itor.next();
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- System.out.println(e.getValue());
- }
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- long stimes2 = System.currentTimeMillis();
- long ctimes2 = Calendar.getInstance().getTimeInMillis();
- long dtimes2 = new Date().getTime();
- System.out.println(stimes2+" "+ctimes2+" "+dtimes2);
- System.out.println((stimes2-stimes1)+" "+(ctimes2-ctimes1)+" "+(dtimes2-dtimes1));
- }
- }