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https://www.edureka.co/blog/wp-content/uploads/2019/09/img-recreate-01-1.jpg

 

ํ•ญ์ƒ ๋ณผ๋•Œ๋งˆ๋‹ค ๋„ˆ๋ฌด ํ—ท๊ฐˆ๋ ค์„œ ๊ธ€๋กœ ์จ๋ด…๋‹ˆ๋‹ค.

 

l HashMap

 

HashMap์ด๋ž€ Map ์ธํ„ฐํŽ˜์ด์Šค ์ข…๋ฅ˜๋กœ์จ key์™€ value ํ˜•ํƒœ๋กœ ๋ฐ์ดํ„ฐ๋ฅผ ์ €์žฅํ•˜๋Š” ๊ตฌ์กฐ๋ฅผ ๊ฐ€์ง‘๋‹ˆ๋‹ค. ๊ทธ๋ฆฌ๊ณ  ์ด๋ฆ„์—์„œ ์•Œ์ˆ˜ ์žˆ๋“ฏ์ด hashing(ํ•ด์‹ฑ)์€ ๋งŽ์˜ ์–‘์˜ ๋ฐ์ดํ„ฐ๋ฅผ ๊ฒ€์ƒ‰ํ•˜๋Š” ๋ฐ ์žˆ์–ด์„œ ๋›ฐ์–ด๋‚œ ์„ฑ๋Šฅ ๋ณด์—ฌ์ค€๋‹ค๊ณ  ํ•ฉ๋‹ˆ๋‹ค.

 

ํ•ด์‹ฑ์ด๋ž€??

 

https://t1.daumcdn.net/cfile/tistory/99CA99335989712D33

 

๋Œ€๋ถ€๋ถ„์˜ ํƒ์ƒ‰ ๋ฐฉ๋ฒ•๋“ค์€ ํƒ์ƒ‰ ํ‚ค๋ฅผ ์ €์žฅ๋œ ํ‚ค ๊ฐ’๊ณผ ๋ฐ˜๋ณต์ ์œผ๋กœ ๋น„๊ตํ•˜๋ฉด์„œ ํƒ์ƒ‰์„ ์›ํ•˜๋Š” ํ•ญ๋ชฉ์— ์ ‘๊ทผํ•ฉ๋‹ˆ๋‹ค. ํ•ด์‹ฑ์€ ํ‚ค ๊ฐ’์— ์ง์ ‘ ์‚ฐ์ˆ ์ ์ธ ์—ฐ์‚ฐ์„ ์ ์šฉํ•˜์—ฌ ํ•ญ๋ชฉ์ด ์ €์žฅ๋˜์–ด ์žˆ๋Š” ํ…Œ์ด๋ธ”์˜ ์ฃผ์†Œ๋ฅผ ๊ณ„์‚ฐํ•˜์—ฌ ํ•ญ๋ชฉ์— ์ ‘๊ทผํ•ฉ๋‹ˆ๋‹ค. ์ด๋ ‡๋“ฏ ํ‚ค ๊ฐ’์˜ ์—ฐ์‚ฐ์— ์˜ํ•ด ์ง์ ‘ ์ ‘๊ทผ์ด ๊ฐ€๋Šฅํ•œ ๊ตฌ์กฐ๋ฅผ ํ•ด์‹œ ํ…Œ์ด๋ธ”์ด๋ผ ํ•˜๊ณ , ํ•ด์‹œ ํ…Œ์ด๋ธ”์„ ์ด์šฉํ•ด ํƒ์ƒ‰ํ•˜๋Š” ๋ฐฉ๋ฒ•์„ ํ•ด์‹ฑ์ด๋ผ๊ณ  ํ•ฉ๋‹ˆ๋‹ค.

 

key๋Š” ์ค‘๋ณต๋˜๋ฉด ์•ˆ๋˜์ง€๋งŒ ๋งŒ์•ฝ ์ค‘๋ณต๋œ๋‹ค๋ฉด ์ตœ๊ทผ key๋กœ ๋Œ€์ฒด๋ฉ๋‹ˆ๋‹ค. value๋Š” ์–ผ๋งˆ๋“ ์ง€ ์ค‘๋ณต์ด ๊ฐ€๋Šฅํ•ฉ๋‹ˆ๋‹ค.

 


l ์ž๋ฐ”์—์„œ ๊ฐ„๋‹จํ•œ HashMap ์‚ฌ์šฉํ•ด๋ณด๊ธฐ

 

package sec01.seco1;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;

public class hashMap {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		HashMap<String, String> map = new HashMap<String, String>();
		
		
		map.put("a","์—์ด");
		map.put("b","๋น„");
		map.put("c","์”จ");
		
		System.out.println(map.get("a")); 
		System.out.println(map);
	}

}

 

 

put ๊ณผ get ์„ ์ด์šฉํ•˜์—ฌ Map์— ์‰ฝ๊ฒŒ ๊ฐ์ฒด๋ฅผ ์ €์žฅํ•˜๊ณ  ๊ฐ€์ ธ์˜ฌ์ˆ˜ ์žˆ์Šต๋‹ˆ๋‹ค.

 


ใ…ฃHashMap์—์„œ ๋ฐ˜๋ณต๋ฌธ ์‚ฌ์šฉํ•ด๋ณด๊ธฐ

 

์ฒซ๋ฒˆ์งธ ๋ฐฉ๋ฒ•

package sec01.seco1;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;

public class hashMap {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		HashMap<String, String> map = new HashMap<String, String>();
		
		
		map.put("a","์—์ด");
		map.put("b","๋น„");
		map.put("c","์”จ");
		

		
		
		System.out.println(map.keySet());
		for(String key : map.keySet()) {
			System.out.println("Key => " + key + "	Value => " + map.get(key));
		}

	}

}

 


๋‘๋ฒˆ์งธ ๋ฐฉ๋ฒ•

 

package sec01.seco1;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;

public class hashMap {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		HashMap<String, String> map = new HashMap<String, String>();
		
		
		map.put("a","์—์ด");
		map.put("b","๋น„");
		map.put("c","์”จ");
		

		System.out.println(map.entrySet());
		for(HashMap.Entry<String, String> entry : map.entrySet()) {
			System.out.println("[key]:" + entry.getKey() + ", [value]:" + entry.getValue());
		}
	}

}

 


์„ธ๋ฒˆ์งธ ๋ฐฉ๋ฒ•

 

Map ์ปฌ๋ ‰์…˜์€ Iterator ์ธํ„ฐํŽ˜์ด์Šค๋ฅผ ์‚ฌ์šฉํ•  ์ˆ˜ ์—†๊ธฐ ๋•Œ๋ฌธ์— HashMap์— entrySet(), keySet() ๋ฉ”์†Œ๋“œ๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ Set ๊ฐ์ฒด๋ฅผ ๋ฐ˜ํ™˜ ๋ฐ›์€ ํ›„ Iterator ์ธํ„ฐํŽ˜์ด์Šค๋ฅผ ์‚ฌ์šฉํ•ด์•ผํ•ฉ๋‹ˆ๋‹ค.

 

package sec01.seco1;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;

public class hashMap {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		HashMap<String, String> map = new HashMap<String, String>();
		
		
		map.put("a","์—์ด");
		map.put("b","๋น„");
		map.put("c","์”จ");
		

		Iterator<HashMap.Entry<String, String>> itE = map.entrySet().iterator();
		while(itE.hasNext()) {
			HashMap.Entry<String, String> entry = (HashMap.Entry<String, String>) itE.next();			
			System.out.println("[key]:" + entry.getKey() + ", [value]:" + entry.getValue());
		}

	}

}

 

 


๋„ค๋ฒˆ์งธ๋ฐฉ๋ฒ•

 

package sec01.seco1;

import java.util.HashMap;
import java.util.Iterator;
import java.util.Map.Entry;
import java.util.Set;

public class hashMap {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		HashMap<String, String> map = new HashMap<String, String>();
		
		
		map.put("a","์—์ด");
		map.put("b","๋น„");
		map.put("c","์”จ");
		

		System.out.println("---------------------------------");
		Iterator<String> itK = map.keySet().iterator();
		while(itK.hasNext()) {
			String key = itK.next();
			System.out.println("[key]:" + key + ", [value]:" + map.get(key));
		}
	
	}

}

 

 

 

์ฝ์–ด์ฃผ์…”์„œ ๊ฐ์‚ฌํ•ฉ๋‹ˆ๋‹ค.

์งˆ๋ฌธ์€ ์–ธ์ œ๋‚˜ ํ™˜์˜ํ•ฉ๋‹ˆ๋‹ค.

 

"๋‚œ ๋ฐ˜๋“œ์‹œ ๋ฐฑ์—”๋“œ ์™•์ด ๋ ๊ฑฐ์•ผ"

๋ฐ˜์‘ํ˜•
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