개발새발 IT

import java.util.HashMap;

import java.util.Hashtable;

import java.util.Set;

public class dailyCode {

public static void main(String[] args) {

Hashtable<String, String> ht = new Hashtable<String, String>();

ht.put("name", "Alex");

ht.put("age", "21");

//ht.put("age", null); Hashtable can't have null value.

HashMap<String, String> hm = new HashMap<String, String>();

hm.put("name", null);

hm.put("age", null); //HashMap can have null value.

hm.put("name", "James");

Set<String> keys = ht.keySet();

for(String key : keys) {

System.out.println(key + " = " + ht.get(key));

}

keys = hm.keySet();

for(String key : keys) {

System.out.println(key + " = " + hm.get(key));

}

}

} 

import java.util.List;

import java.util.ArrayList;

public class dailyCode {

public static void main(String[] args) {

List<String> strList = new ArrayList<String>();

strList.add("aaa");

strList.add("bbb");

strList.add("ccc");

List<Integer> intList = new ArrayList<Integer>();

intList.add(111);

intList.add(222);

intList.add(333);

printList(strList);

printList(intList);

}

private static void printList(List<?> list) {

for(Object obj : list) {

System.out.println(obj);

}

System.out.println("---");

}

} 

public class dailyCode {

public static void main(String[] args) {

int[] src = {1, 2, 3, 4, 5};

int[] dst = {0, 0, 0, 0, 0, 6, 7, 8, 9, 10};

int[] newSrc = {0, 0, 0, 0, 0};

System.arraycopy(src, 0, dst, 0, src.length);

for(int i : dst) {

System.out.print(i + " ");

}

System.out.println("");

System.arraycopy(newSrc, 0, dst, 5, src.length);

for(int i : dst) {

System.out.print(i + " ");

}

System.out.println("");

System.arraycopy(newSrc, 0, dst, 1, 2);

for(int i : dst) {

System.out.print(i + " ");

}

}

}