Java

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String → StringBuilder

java.util.Date ↔ java.time.Instant
java.util.Calendar → java.time.Instant
java.text.SimpleDateFormat
java.time
- Local
- Zoned
- Offset
Collections
- List; ArrayList, LinkedList
- Set; HashSet, LinkedHashSet
- Map; HashMap, LinkedHashMap

람다식

(자료형 인수, ...) -> { ... 임의의 처리 ...}

import java.sql.*;

...
...
  Connection conn = null;
  
  try
  {
    Class.forName("DRIVER");
  }
  catch(ClassNotFoundException e)
  {
    e.printStackTrace();
  }
  
  try
  {
    conn = DriverManager.getConnection("jdbc database", "user", "password");
    
    Statement stmt = conn.createStatement();
    ResultSet rset = stmt.executeQuery("QUERY");
    
    while(rset.next())
    {
      // do something
    }
  }
  catch(SQLException e)
  {
    e.printStackTrace();
  }
  finally
  {
    if(conn != null)
    {
      try
      {
        conn.close();
        conn = null;
      }
      catch(SQLException e)
      {
        e.printStackTrace();
      }
    }
  }
  
...
...

conn.setAutoCommit(true/false);
conn.commit();
conn.rollback()
PreparedStatement stmt = conn.prepareStatement(“…. ?”);
- stmt.setString(1, “value”);

DAO^{Data Access Object}
DTO^{Data Transfer Object}
JPA^{Java Persistence API}

FileReader
BufferedReader
Scanner
Files

CSV, XML, LOGGER

JUint
- @Test
- @Before
- @After
- @BeforeClass
- @AfterClass
- @Ignore
- import static org.junit.Assert.*;
  - assertEquals()
  - fail()
  - assertThat()
  - import static org.hamcrest.CoreMatchers.*;
    - is()
JMockit
DbUnit