File 읽기

File

import java.io.File;

public class FileEx {

  public static void main(String[] args) {
    File file = new File("c:\\windows\\system.ini");
    System.out.println(file.getPath());
    System.out.println(file.getParent());
    System.out.println(file.getName());
    if (file.isFile()) {
      System.out.println("파일입니다.");
    } else {
      System.out.println("디렉토리입니다.");
    }
    File file02 = new File("c:\\Temp\\java");
    if (!file02.exists()) {
      file02.mkdir();
    }
    File file03 = new File("c:\\Temp");
    File subFiles[] = file03.listFiles();
    for (int i = 0; i < subFiles.length; i++) {
      File f = subFiles[i];
      System.out.println(f.getName());
      System.out.println(f.isFile() ? "파일" : "폴더");
    }
  }
}

FileInputStream

import java.io.FileInputStream;

//import java.io.FileNotFoundException;

/**
 * FileInputSteamEx
 */
public class FileInputSteamEx {

  public static void main(String[] args) {
    byte b[] = new byte[6];
    try {
      FileInputStream fileInput = new FileInputStream("c:\\Temp\\test.out");
      int n = 0;
      int c = 0;
      while ((c = fileInput.read()) != -1) {
        b[n] = (byte) c;
        n++;
      }

      fileInput.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

FileOutputStream

//import java.io.FileNotFoundException;
import java.io.FileOutputStream;

public class FileOutputSteamEx {

  public static void main(String[] args) {
    byte b[] = { 7, 51, 3, 4, 24, -1 };
    try {
      FileOutputStream fout = new FileOutputStream("c:\\Temp\\test.out");
      for (int i = 0; i < b.length; i++) {
        fout.write(b[i]);
      }

      fout.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

FileReader

//import java.io.FileNotFoundException;
import java.io.FileReader;

public class FileReaderEx {

  public static void main(String[] args) {
    FileReader fio = null;
    try {
      fio = new FileReader("c:\\windows\\system.ini");
      int c;
      while ((c = fio.read()) != -1) {
        System.out.print((char) c);
      }
      fio.close();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

FileRead-한글

import java.io.FileInputStream;
import java.io.InputStreamReader;

//import java.io.UnsupportedEncodingException;

public class FileReadHangul {

  public static void main(String[] args) {
    InputStreamReader in = null;
    FileInputStream fin = null;
    try {
      fin = new FileInputStream("c:\\Temp\\hangul.txt");
      in = new InputStreamReader(fin, "utf-8");
      System.out.println(in.getEncoding());
      int c;
      while ((c = in.read()) != -1) {
        System.out.print((char) c);
      }
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

FileWriter

import java.io.FileWriter;
import java.io.IOException;
import java.util.Scanner;

public class FileWriterEx {

  public static void main(String[] args) {
    Scanner scanner = new Scanner(System.in);
    FileWriter fileWriter = null;
    try {
      fileWriter = new FileWriter("c:\\Temp\\test.txt");
      while (true) {
        String line = scanner.nextLine();
        if (line.length() == 0) {
          break;
        }
        fileWriter.write(line, 0, line.length());
        fileWriter.write("\r\n", 0, 2);
      }
      fileWriter.close();
      scanner.close();
    } catch (IOException e) {
      e.printStackTrace();
    }
  }
}

BufferedIO

import java.io.BufferedOutputStream;
//import java.io.FileNotFoundException;
import java.io.FileReader;

public class BufferedIOEx {

  public static void main(String[] args) {
    FileReader fin = null;
    int c;
    try {
      fin = new FileReader("c:\\Temp\\test02.txt");
      // buffer는 정해진 사이즈를 넘어서야지만 전송 시작 강제로 보내고 싶을때는 flush();
      BufferedOutputStream out = new BufferedOutputStream(System.out, 20);
      while ((c = fin.read()) != -1) {
        out.write(c);
      }
      out.flush();
    } catch (Exception e) {
      e.printStackTrace();
    }
  }
}

Ex. 사전

package practice;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.util.Scanner;
import java.util.Vector;

class WordSearch {

  private Vector<String> wordList = new Vector<String>();

  private void wordRead() {
    try {
      File file = new File("c:\\Temp\\words.txt");
      Scanner readWord = new Scanner(new FileReader(file));
      while (readWord.hasNext()) {
        String line = readWord.nextLine();
        wordList.add(line);
      }
      System.out.println(
        "프로젝트 폴더 밑의 " + file.getName() + " 파일을 읽었습니다...."
      );
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    }
  }

  private void wordSearching() {
    Scanner scanner = new Scanner(System.in);
    int cnt = 0;
    while (true) {
      System.out.print("단어>> ");
      String Input = scanner.nextLine();
      if (Input.equals("그만")) {
        System.out.println("종료합니다....");

        break;
      }
      for (int i = 0; i < wordList.size(); i++) {
        if (wordList.get(i).startsWith(Input)) {
          System.out.println(wordList.get(i));
          cnt += 1;
        }
      }
      if (cnt == 0) {
        System.out.println("발견할 수 없음");
      }
    }
    scanner.close();
  }

  public void run() {
    wordRead();
    wordSearching();
  }
}

public class Practice11 {

  public static void main(String[] args) {
    WordSearch wordSearch = new WordSearch();
    wordSearch.run();
  }
}

자바 스윙(Swing)

Basic

Flow Layout

Border Layout

Grid Layout

Null Layout

자바 스윙으로 계산기 디자인

package Practice;

import java.awt.*;
import javax.swing.*;

public class Practice07 extends JFrame {

  public Practice07() {
    setTitle("Calc");
    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    setSize(500, 400);
    setVisible(true);

    Container contentPane = getContentPane();

    JPanel northJ = new JPanel();
    northJ.setBackground(Color.gray);
    northJ.setSize(500, 50);
    northJ.setLayout(new FlowLayout());
    northJ.add(new JLabel("수식 입력"));
    northJ.add(new JTextField(16));

    JPanel centerJ = new JPanel();

    centerJ.setLayout(new GridLayout(4, 4, 5, 5));

    for (int i = 0; i < 10; i++) {
      JButton btn = new JButton(" " + i);
      centerJ.add(btn);
    }

    String mark[] = { "CE", "계산", "+", "-", "x", "/" };

    for (int i = 0; i < mark.length; i++) {
      if (i >= 0 || i < 2) {
        JButton btn = new JButton(mark[i]);
        centerJ.add(btn);
      } else if (i >= 2 || i < mark.length) {
        JButton btn = new JButton(mark[i]);
        centerJ.add(btn).setBackground(Color.GREEN);
      }
    }

    JPanel southJ = new JPanel();

    southJ.setBackground(Color.yellow);
    southJ.setSize(500, 50);
    southJ.setLayout(new FlowLayout());
    southJ.add(new JLabel("계산 결과"));
    southJ.add(new JTextField(16));

    contentPane.add(northJ, BorderLayout.NORTH);
    contentPane.add(centerJ, BorderLayout.CENTER);
    contentPane.add(southJ, BorderLayout.SOUTH);
  }

  public static void main(String[] args) {
    new Practice07();
  }
}

스윙 이벤트

Action Listener - 클릭 이벤트

• 클릭하면 숫자가 영어로 바뀌면서 구구단이 출력

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

class MyActionListener implements ActionListener {

  public void gugudanOut(int dan) {
    for (int j = 1; j <= 9; j++) {
      int result = dan * j;
      System.out.println(dan + " x " + j + " = " + result);
    }
    System.out.println();
  }

  public void actionPerformed(ActionEvent e) {
    JButton button = (JButton) e.getSource(); // 선택된 구구단 버튼

    if (button.getText().equals("1")) {
      button.setText("One");
      gugudanOut(1);
    } else if (button.getText().equals("2")) {
      button.setText("Two");
      gugudanOut(2);
    } else if (button.getText().equals("3")) {
      button.setText("Three");
      gugudanOut(3);
    } else if (button.getText().equals("4")) {
      button.setText("Four");
      gugudanOut(4);
    } else if (button.getText().equals("5")) {
      button.setText("Five");
      gugudanOut(5);
    } else if (button.getText().equals("6")) {
      button.setText("Six");
      gugudanOut(6);
    } else if (button.getText().equals("7")) {
      button.setText("Seven");
      gugudanOut(7);
    } else if (button.getText().equals("8")) {
      gugudanOut(8);
      button.setText("Eight");
    } else if (button.getText().equals("9")) {
      gugudanOut(9);
      button.setText("Nine");
    } else {
      System.out.println();
    }
  }
}

public class IndependentClassListener extends JFrame {

  public IndependentClassListener() {
    this.setTitle("Action Event");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    Container contentPane = getContentPane();
    contentPane.setLayout(new GridLayout(3, 3, 10, 10));

    JButton btn[] = new JButton[9];

    for (int i = 0; i < 9; i++) {
      btn[i] = new JButton(Integer.toString(i + 1));
      contentPane.add(btn[i]);
    }

    for (int i = 0; i < btn.length; i++) {
      btn[i].addActionListener(new MyActionListener());
    }

    for (int i = 0; i < btn.length; i++) {
      contentPane.add(btn[i]);
    }

    this.setSize(400, 300);
    this.setVisible(true);
  }

  public static void main(String[] args) {
    new IndependentClassListener();
  }
}

익명 함수

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class AnonymousClassListener extends JFrame {

  public AnonymousClassListener() {
    this.setTitle("Action Event");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    Container contentPane = getContentPane();
    contentPane.setLayout(new FlowLayout());

    JButton btn = new JButton("Action");

    btn.addActionListener(
      new ActionListener() {
        @Override
        public void actionPerformed(ActionEvent e) {
          JButton btn = (JButton) e.getSource();
          if (btn.getText().equals("Action")) {
            btn.setText("액션!");
          } else {
            btn.setText("Action");
          }
          setTitle("바껴라");
        }
      }
    );

    contentPane.add(btn);
    this.setSize(400, 300);
    this.setVisible(true);
  }

  public static void main(String[] args) {
    new AnonymousClassListener();
  }
}

Mouse Event

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class MouseEventEx extends JFrame {

  private JLabel la = new JLabel("Hello");

  class MyMouseListener implements MouseListener {

    public void mousePressed(MouseEvent e) {
      int x = e.getX();
      int y = e.getY();
      la.setLocation(x, y);
    }

    public void mouseReleased(MouseEvent e) {}

    public void mouseClicked(MouseEvent e) {}

    public void mouseEntered(MouseEvent e) {}

    public void mouseExited(MouseEvent e) {}
  }

  public MouseEventEx() {
    setTitle("Moust Event 예제");

    setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

    Container c = getContentPane();
    c.addMouseListener(new MyMouseListener());

    c.setLayout(null);
    la.setSize(50, 20);
    la.setLocation(30, 30);
    c.add(la);

    setSize(250, 250);
    setVisible(true);
  }

  public static void main(String[] args) {
    new MouseEventEx();
  }
}

Moust Adapter

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class MouseAdapterEx extends JFrame {

  class myMouseAdapter extends MouseAdapter {

    public void mousePressed(MouseEvent e) {
      System.out.println("Connected..");
    }
  }

  private JLabel label = new JLabel("hello");

  public MouseAdapterEx() {
    this.setTitle("Mouse Adapter");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container contentPane = this.getContentPane();

    contentPane.addMouseListener(new myMouseAdapter());
    contentPane.setLayout(null);

    label.setLocation(100, 100);
    label.setSize(50, 20);
    contentPane.add(label);

    this.setSize(300, 300);
    this.setVisible(true);
  }

  public static void main(String[] args) {
    new MouseAdapterEx();
  }
}

Key Listener

KeyAdapter + MouseAdapter

• Hello Label 옮기기

package practice;

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class MovingHello extends JFrame {

  private JLabel label = new JLabel("Hello");
  private int moving = 10;

  class MyMouseAdapter extends MouseAdapter {

    // 마우스 찍은 위치로 Hello 옮기기
    public void mousePressed(MouseEvent e) {
      //super.mousePressed(e);
      int x = e.getX();
      int y = e.getY();
      label.setLocation(x, y);
    }
  }

  class MyKeyListener extends KeyAdapter {

    // 상하좌우 키로 Hello 옮기기
    public void keyPressed(KeyEvent e) {
      int keyCode = e.getKeyCode();

      if (keyCode == KeyEvent.VK_UP) {
        label.setLocation(label.getX(), label.getY() - moving);
      } else if (keyCode == KeyEvent.VK_DOWN) {
        label.setLocation(label.getX(), label.getY() + moving);
      } else if (keyCode == KeyEvent.VK_LEFT) {
        label.setLocation(label.getX() - moving, label.getY());
      } else if (keyCode == KeyEvent.VK_RIGHT) {
        label.setLocation(label.getX() + moving, label.getY());
      }
    }

    public void keyReleased(KeyEvent e) {}

    public void keyTyped(KeyEvent e) {}
  }

  public MovingHello() {
    this.setTitle("KeyListener");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container contentPane = this.getContentPane();
    contentPane.setLayout(new FlowLayout());

    // 마우스 찍은 위치로 Hello 옮기기
    contentPane.addMouseListener(new MyMouseAdapter());
    // 상하좌우 키로 Hello 옮기기
    contentPane.addKeyListener(new MyKeyListener());
    contentPane.add(label);

    this.setSize(300, 300);
    this.setVisible(true);
    contentPane.setFocusable(true); // 이게 있어야 키보드 입력 이벤트 가능
    contentPane.requestFocus(); // 이것도 마찬가지
  }

  public static void main(String[] args) {
    new MovingHello();
  }
}

Mouse Adapter : 더블클릭

• 더블클릭하면 배경색이 바뀌는 스윙

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class MouseDoubleClickEx extends JFrame {

  class MyMouseListener extends MouseAdapter {

    public void mousePressed(MouseEvent e) {
      int clickCounts = e.getClickCount();
      Container c = (Container) e.getSource();
      if (clickCounts > 1 && c.getBackground() == Color.GREEN) {
        c.setBackground(Color.WHITE);
      } else if (clickCounts > 1) {
        c.setBackground(Color.GREEN);
      }
    }
  }

  public MouseDoubleClickEx() {
    this.setTitle("double click and back color will change");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container contentPane = this.getContentPane();
    contentPane.add(
      new JLabel("더블클릭:초록 / 다시 더블클릭:디폴트"),
      BorderLayout.CENTER
    );
    contentPane.addMouseListener(new MyMouseListener());
    this.setSize(300, 300);
    this.setVisible(true);
  }

  public static void main(String[] args) {
    new MouseDoubleClickEx();
  }
}

MouseListener, MouseMotionListener

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class MouseListenerAllEx extends JFrame {

  JLabel label = new JLabel("No Mouse Event");

  // 인터페이스는 이중상속(구현) 가능
  class MyMouseListener implements MouseListener, MouseMotionListener {

    public void mouseClicked(MouseEvent e) {}

    public void mousePressed(MouseEvent e) {
      label.setText("Mouse Pressed / " + e.getX() + " / " + e.getY());
    }

    public void mouseReleased(MouseEvent e) {
      label.setText("Mouse Released / " + e.getX() + " / " + e.getY());
    }

    public void mouseEntered(MouseEvent e) {}

    public void mouseExited(MouseEvent e) {}

    public void mouseDragged(MouseEvent e) {
      label.setText("Mouse Dragged / " + e.getX() + " / " + e.getY());
    }

    public void mouseMoved(MouseEvent e) {
      label.setText("Mouse Moved / " + e.getX() + " / " + e.getY());
    }
  }

  public MouseListenerAllEx() {
    this.setTitle("All Mouse Event");
    this.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    Container contentPane = this.getContentPane();
    contentPane.addMouseListener(new MyMouseListener());
    contentPane.addMouseMotionListener(new MyMouseListener());
    contentPane.setLayout(new BorderLayout());
    contentPane.add(label, BorderLayout.CENTER);

    this.setSize(500, 500);
    this.setVisible(true);
  }

  public static void main(String[] args) {
    new MouseListenerAllEx();
  }
}