4일차 추가
List<MemberVO> vos= Arrays.asList(
new MemberVO(10, "admin10", "pw10", "name10", "tel10"),
new MemberVO(11, "admin11", "pw11", "name11", "tel11"),
new MemberVO(13, "admin13", "pw13", "name13", "tel13")
);
vos.sort(new Comparator<MemberVO>() {
@Override
public int compare(MemberVO o1, MemberVO o2) {
return o1.getId().compareTo(o2.getId());
}
});
List<String> names2 = Arrays.asList("yang", "kim", "lee", "lee");
System.out.println(names2);
System.out.println(names2.stream().distinct().toArray());
System.out.println(names2.stream().filter((item) -> item.startsWith("l")));
System.out.println(names2.stream().filter((item) -> item.startsWith("l")).count());
for (Object string : names2.stream().map((item) -> item.startsWith("l")).toArray()) {
System.out.println(string);
}
for (Object string : names2.stream().map((item) -> "[" + item + "]").toArray()) {
System.out.println(string);
}
for (Object x : names2.stream().distinct().toArray()) {
System.out.println(x);
}
String str = "Yang";
System.out.println(str.startsWith("Ya"));
System.out.println(str.endsWith("ng"));
names.forEach(System.out::println);
Date Object
package test.com;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.GregorianCalendar;
public class TestDate {
public static void main(String[] args) {
System.out.println(new Date());
System.out.println(new Date().getTime());
System.out.println(new GregorianCalendar().getTime());
System.out.println(new java.sql.Date(System.currentTimeMillis()));
System.out.println(new java.sql.Time(System.currentTimeMillis()));
System.out.println("====================================");
System.out.println(new java.sql.Timestamp(System.currentTimeMillis()));
System.out.println(new java.sql.Timestamp(System.currentTimeMillis()).getTime());
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss.SSS");
System.out.println(sdf.format(new Date()));
}
}
String Object
package test.com;
public class TestString {
public static void main(String[] args) {
System.out.println("문자열 및 대용량 문자열 처리법");
getBuffer();
StringBuffer sb = new StringBuffer();
sb.append("bbb");
StringBuilder sbuilder = new StringBuilder();
sbuilder.append("ccc");
String data = "aaa bbb ccc ddd";
System.out.println(data.indexOf("cc"));
System.out.println(data.indexOf("x"));
String[] strs = data.split(" ");
}
private static void getBuffer() {
long startTime = System.currentTimeMillis();
StringBuilder sbuilder = new StringBuilder();
for (int i = 0; i < 100000; i++) {
sbuilder.append(i);
}
System.out.println(sbuilder.length());
System.out.println(System.currentTimeMillis() - startTime);
}
private static void getStringTime() {
long startTime = System.currentTimeMillis();
CharSequence name = "kim";
for (int i = 0; i < 100000; i++) {
name = name.toString() + i;
}
System.out.println(name.length());
System.out.println(System.currentTimeMillis() - startTime);
}
}
JDBC
private Connection conn;
private PreparedStatement pstmt;
private ResultSet rs;
private final String url = "jdbc:mysql://localhost:3306/${DB이름}?useUnicode=true&characterEncoding=utf8&serverTimezone=UTC";
private final String user_id = "root";
private final String user_pw = "1234";
try {
Class.forName("com.mysql.cj.jdbc.Driver");
System.out.println("Driver successed...");
} catch (ClassNotFoundException e) {
e.printStackTrace();
}
- 쿼리문 실행 (DML -
INSERT
, DELETE
, UPDATE
)
public int insert(BoardVO vo) {
int flag = 0;
try {
conn = DriverManager.getConnection(url, user_id, user_pw);
System.out.println("conn successed...");
pstmt = conn.prepareStatement("INSERT INTO board(title, content, author) VALUES(?, ?, ?)");
pstmt.setString(1, vo.getTitle());
pstmt.setString(2, vo.getContent());
pstmt.setString(3, vo.getAuthor());
flag = pstmt.executeUpdate();
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (pstmt != null) {
try {
pstmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
return flag;
}
public ArrayList<BoardVO> searchList(String searchKey, String searchWord) {
ArrayList<BoardVO> result = new ArrayList<>();
try {
conn = DriverManager.getConnection(url, user_id, user_pw);
System.out.println("conn successed...");
pstmt = conn.prepareStatement("SELECT * FROM board WHERE " + searchKey + " LIKE ?;");
pstmt.setString(1, "%" + searchWord + "%");
rs = pstmt.executeQuery();
while (rs.next()) {
BoardVO vo = new BoardVO();
vo.setNum(rs.getInt("num"));
vo.setTitle(rs.getString("title"));
vo.setContent(rs.getString("content"));
vo.setAuthor(rs.getString("author"));
result.add(vo);
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (rs != null) {
try {
rs.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (pstmt != null) {
try {
pstmt.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
if (conn != null) {
try {
conn.close();
} catch (SQLException e) {
e.printStackTrace();
}
}
}
return result;
}
}