import java.util.HashMap; |
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import java.util.Iterator; |
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import java.util.LinkedHashMap; |
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import java.util.Map; |
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import java.util.Map.Entry; |
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import java.util.Set; |
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import org.junit.Test; |
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//Map集合取数据的四种方法 |
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public class MapFetch
{ |
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//
第一种方法(传统方法) |
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@Test |
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public void funOne()
{ |
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Map
map = new HashMap(); |
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map.put( "1" , "第一个数" ); |
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map.put( "2" , "第二个数" ); |
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map.put( "3" , "第三个数" ); |
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Set
set = map.keySet(); |
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Iterator
it = set.iterator(); |
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while (it.hasNext())
{ |
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String
key = (String) it.next(); |
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String
value = (String) map.get(key); |
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System.out.println(key
+ "=" +
value); |
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} |
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} |
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//
第二种方法(传统方法) |
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@Test |
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public void funTwo()
{ |
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Map
map = new HashMap(); |
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map.put( "1" , "第一个数" ); |
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map.put( "2" , "第二个数" ); |
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map.put( "3" , "第三个数" ); |
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Set
set = map.entrySet(); |
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Iterator
it = set.iterator(); |
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while (it.hasNext())
{ |
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Entry
entry = (Entry) it.next(); |
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String
key = (String) entry.getKey(); |
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String
value = (String) entry.getValue(); |
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System.out.println(key
+ "=" +
value); |
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} |
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} |
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//
第三种方法(增强for循环方法) |
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@Test |
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public void funThree()
{ |
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Map
map = new LinkedHashMap(); |
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map.put( "1" , "第一个数" ); |
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map.put( "2" , "第二个数" ); |
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map.put( "3" , "第三个数" ); |
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for (Object
obj : map.keySet()) { |
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String
key = (String) obj; |
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String
value = (String) map.get(key); |
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System.out.println(key
+ "=" +
value); |
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} |
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} |
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//
第四种方法(增强for循环方法) |
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@Test |
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public void funFour()
{ |
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Map
map = new LinkedHashMap(); |
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map.put( "1" , "第一个数" ); |
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map.put( "2" , "第二个数" ); |
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map.put( "3" , "第三个数" ); |
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for (Object
obj : map.entrySet()) { |
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Entry
entry = (Entry) obj; |
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String
key = (String) entry.getKey(); |
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String
value = (String) entry.getValue(); |
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System.out.println(key
+ "=" +
value); |
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} |
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} |
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} |