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HashMapExample1.java
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/
HashMapExample1.java
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package collection.map.hashmap;
import java.util.HashMap;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
public class HashMapExample1 {
public static void main(String[] args) {
//Map Collection 생성
Map<String, Integer> map = new HashMap<String, Integer>();
map.put("신용권", 85);
map.put("홍길동", 90);
map.put("동장군", 80);
map.put("홍길동", 95); // 홍길동 변경됨
System.out.println("총 Entry 수: " + map.size()); //총 Entry 수: 3
System.out.println("홍길동: " + map.get("홍길동")); //95
System.out.println();
Set<String> keySet = map.keySet();
Iterator<String> keyIterator = keySet.iterator();
while(keyIterator.hasNext()){
String key = keyIterator.next();
Integer value = map.get(key);
System.out.println("\t" + key + ": " + value );
}
// 홍길동: 95
// 신용권: 85
// 동장군: 80
System.out.println();
map.remove("홍길동");
System.out.println("총 Entry 수: " + map.size()); //총 Entry 수: 2
Set<Map.Entry<String, Integer>> entrySet = map.entrySet();
Iterator<Map.Entry<String, Integer>> entryIterator = entrySet.iterator();
while(entryIterator.hasNext()){
Map.Entry<String, Integer> entry = entryIterator.next();
String key = entry.getKey();
Integer value = entry.getValue();
System.out.println("\t" + key + ": " + value );
}
// 신용권: 85
// 동장군: 80
System.out.println();
map.clear();
System.out.println("총 Entry 수: " + map.size()); //총 Entry 수: 0
}
}