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import java.io.BufferedReader;  
import java.io.IOException;  
import java.io.InputStreamReader;  
  
public class KeyboardIOExam {  
    public static void main(String[] args) throws IOException {  

        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));  
        String line = null;  
        while ((line = br.readLine()) != null) {  
            System.out.println("읽어들인 값 : " + line);  
        }  
    }  
}

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import java.io.File;  
import java.io.IOException;  
  
public class FileInfo {  
    public static void main(String[] args) {  
        if (args.length != 1) {  
            System.out.println("사용법 : FileInfo 파일이름");  
            System.exit(0);  
        }   // if end  
  
        File f = new File(args[0]);  
  
        // 파일이 존재할 경우  
        if (f.exists()) {  
            System.out.println("length : " + f.length());  
            System.out.println("canRead : " + f.canRead());  
            System.out.println("canWrite : " + f.canWrite());  
            System.out.println("getAbsolutePath : " + f.getAbsolutePath());  
  
            try {  
                System.out.println("getCanonicalPath : " + f.getCanonicalPath());  
            } catch (IOException e) {  
                System.out.println(e);  
            }  
  
            System.out.println("getName : " + f.getName());  
            System.out.println("getParent : " + f.getParent());  
            System.out.println("getPath : " + f.getPath());  
        }  
  
        // 파일이 존재하지 않을 경우  
        else {  
            System.out.println("파일이 존재하지 않습니다.");  
        }  
    }  
}

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import java.io.File;  
  
public class FileDelete {  
    public static void main(String[] args) {  
        if (args.length != 1) {  
            System.out.println("사용법 : java FileDelete 파일이름");  
            System.exit(0);  
        }   // if end  
  
        File f = new File(args[0]);  
          
        if (f.exists()) {  
            boolean deleteflag = f.delete();  
            if(deleteflag)  
                System.out.println("파일 삭제를 성공하였습니다.");  
            else  
                System.out.println("파일 삭제를 실패하였습니다.");  
        } else {  
            System.out.println("파일이 존재하지 않습니다.");  
        }  
    }  
}

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public class FileList {  
    public static void main(String[] args) {  
        File file = new File("/Users/jaeyoon/Desktop");  
        printFiles(file);  
    }  
  
    private static void printFiles(File file) {  
        if (file.isDirectory()) {  
            File[] files = file.listFiles();  
            for (int i = 0; i < files.length; i++) {  
                System.out.println("[dir] - " + files[i]);  
                printFiles(files[i]);  
            }  
        } else {  
            System.out.println(file.getName());  
        }  
    }  
}

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import java.io.File;  
import java.io.IOException;  
  
public class TempFile {  
    public static void main(String[] args) {  
        try {  
            File f = File.createTempFile("tmp_", ".dat");  
            System.out.println(f.getAbsolutePath());  
            System.out.println("10초 동안 멈춰있습니다.");  
  
            try {  
                Thread.sleep(10000); // 10초 동안 프로그램 멈춤  
            } catch (InterruptedException e) {  
                System.out.println(e);  
            }  
  
            f.deleteOnExit();   // JVM이 종료될 때 임시파일을 자동으로 삭제  
        } catch (IOException e) {  
            System.out.println(e);  
        }  
    }  
}

// /var/folders/mc/pg8hsl1s6ng960_zspk455cc0000gn/T/tmp_17714656951715397422.dat
//  10초 동안 멈춰있습니다.

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import java.io.IOException;  
import java.io.InputStream;  
  
public class InputStreamExam01 {  
    public static void main(String[] args) {  
        InputStream in = null;  
        try {  
            int data = in.read();  
        } catch (IOException e) {  
            System.out.println("io 오류 : " + e);  
        } finally {  
            try {  
                in.close();  
            } catch (Exception e) {  
                System.out.println("io 오류 : " + e);  
            }  
        }  
    }  
}

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import java.io.FileOutputStream;  
import java.io.OutputStream;  
  
public class HelloIO01 {  
    public static void main(String[] args) throws Exception {  
        OutputStream out = new FileOutputStream("/Users/jaeyoon/Desktop/hello01.dat");  
        out.write(1); // 0000 0000  0000 0000   0000 0000   0000 0001  
        out.write(255);  
        out.write(0);  
        out.close();  
    }  
}

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import java.io.FileInputStream;  
import java.io.InputStream;  
  
public class HelloIO02 {  
    public static void main(String[] args) throws Exception {  
        InputStream in = new FileInputStream("/Users/jaeyoon/Desktop/hello01.dat");  
        int i1 = in.read();  
        System.out.println(i1); // 1  
        int i2 = in.read();  
        System.out.println(i2); // 255  
        int i3 = in.read();  
        System.out.println(i3); // 0  
        int i4 = in.read();  
        System.out.println(i4); // -1, 파일의 끝 EOF        in.close();  
    }  
}

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import java.io.FileInputStream;  
import java.io.InputStream;  
  
public class HelloIO02 {  
    public static void main(String[] args) throws Exception {  
        InputStream in = new FileInputStream("/Users/jaeyoon/Desktop/hello01.dat");  
        int buf = -1;  
        while ((buf = in.read()) != -1) {  
            System.out.println(buf);  
        }  
        in.close();  
    }  
}

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public class HelloIO03 {  
    public static void main(String[] args) throws Exception {  
        Writer out = new FileWriter("/Users/jaeyoon/Desktop/hello.txt");  
        out.write((int)'a');  
        out.write((int)'h');  
        out.write((int)'!');  
        out.close();  
    }  
}

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import java.io.FileReader;  
import java.io.Reader;  
  
public class HelloIO04 {  
    public static void main(String[] args) throws Exception {  
        Reader in = new FileReader("/Users/jaeyoon/Desktop/hello.txt");  
        int ch = -1;  
        while ((ch = in.read()) != -1) {  
            System.out.println((char)ch);  
        }  
        in.close();  
    }  
}

// 가
// 나
// 다

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import java.io.FileOutputStream;  
import java.io.OutputStreamWriter;  
import java.io.PrintWriter;  
  
public class HelloIO05 {  
    public static void main(String[] args) throws Exception {  
        PrintWriter out = new PrintWriter(new OutputStreamWriter(new FileOutputStream("/Users/jaeyoon/Desktop/my.txt")));  
        out.println("hello");  
        out.println("world");  
        out.println("!!!!");  
        out.close();  
    }  
}

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import java.io.BufferedReader;  
import java.io.FileInputStream;  
import java.io.InputStreamReader;  
  
public class HelloIO06 {  
    public static void main(String[] args) throws Exception {  
        BufferedReader in = new BufferedReader(new InputStreamReader(new FileInputStream("/Users/jaeyoon/Desktop/my.txt")));  
        String line = null;  
        while ((line = in.readLine()) != null) {  
            System.out.println(line);  
        }  
        in.close();  
    }  
}

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public class ObjectOutputExam {  
    public static void main(String[] args) throws Exception {  
        User user = new User("uni@example.com", "신재윤", 1996);  
        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("/Users/jaeyoon/Desktop/user.dat"));  
        out.writeObject(user);  
        out.close();  
    }  
}

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public class ObjectInputExam {  
    public static void main(String[] args) throws Exception {  
        ObjectInputStream in = new ObjectInputStream(new FileInputStream("/Users/jaeyoon/Desktop/user.dat"));  
        User user = (User)in.readObject();  
        in.close();  
        System.out.println(user);  
    }  
}

// User{email='uni@example.com', name='신재윤', birthYear=1996}

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public class ObjectOutputExam {  
    public static void main(String[] args) throws Exception {  
        User user1 = new User("uni@example.com", "신재윤", 1996);  
        User user2 = new User("zzzzz@example.com", "홍길동", 1986);  
        User user3 = new User("asdfasdf@example.com", "둘리", 1972);  
        ArrayList<User> list = new ArrayList<>();  
        list.add(user1);  
        list.add(user2);  
        list.add(user3);  
  
        ObjectOutputStream out = new ObjectOutputStream(new FileOutputStream("/Users/jaeyoon/Desktop/userlist.dat"));  
        out.writeObject(list);  
        out.close();  
    }  
}

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public class ObjectInputExam {  
    public static void main(String[] args) throws Exception {  
        ObjectInputStream in = new ObjectInputStream(new FileInputStream("/Users/jaeyoon/Desktop/userlist.dat"));  
        ArrayList<User> list = (ArrayList)in.readObject();  
        in.close();  
        for (int i = 0; i < list.size(); i++) {  
            System.out.println(list.get(i));  
        }  
    }  
}

// User{email='uni@example.com', name='신재윤', birthYear=1996}
// User{email='zzzzz@example.com', name='홍길동', birthYear=1986}
// User{email='asdfasdf@example.com', name='둘리', birthYear=1972}

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public class ObjectInputOutExam {  
    public static void main(String[] args) throws Exception {  
        User user1 = new User("uni@example.com", "신재윤", 1996);  
        User user2 = new User("zzzzz@example.com", "홍길동", 1986);  
        User user3 = new User("asdfasdf@example.com", "둘리", 1972);  
        ArrayList<User> list = new ArrayList<>();  
        list.add(user1);  
        list.add(user2);  
        list.add(user3);

		ArrayList<User> list2 = list;  
		  
		for (int i = 0; i < list2.size(); i++) {  
		    System.out.println(list2.get(i));  
		}

		list.remove(2);
		System.out.println(list.size());
		System.out.println(list2.size());
    }
}

// User{email='uni@example.com', name='신재윤', birthYear=1996}
// User{email='zzzzz@example.com', name='홍길동', birthYear=1986}
// User{email='asdfasdf@example.com', name='둘리', birthYear=1972}
// 2
// 2

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public class ObjectInputOutExam {  
    public static void main(String[] args) throws Exception {  
        User user1 = new User("uni@example.com", "신재윤", 1996);  
        User user2 = new User("zzzzz@example.com", "홍길동", 1986);  
        User user3 = new User("asdfasdf@example.com", "둘리", 1972);  
        ArrayList<User> list = new ArrayList<>();  
        list.add(user1);  
        list.add(user2);  
        list.add(user3);

		ArrayList<User> list2 = new ArrayList<>();  
		  
		for (int i = 0; i < list2.size(); i++) {  
		    list2.add(list.get(i));  
		}

		list.remove(2);
		System.out.println(list.size());
		System.out.println(list2.size());
    }
}

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public class ObjectInputOutExam {  
    public static void main(String[] args) throws Exception {  
        User user1 = new User("uni@example.com", "신재윤", 1996);  
        User user2 = new User("zzzzz@example.com", "홍길동", 1986);  
        User user3 = new User("asdfasdf@example.com", "둘리", 1972);  
        ArrayList<User> list = new ArrayList<>();  
        list.add(user1);  
        list.add(user2);  
        list.add(user3);  
  
        ByteArrayOutputStream bout = new ByteArrayOutputStream();  
        ObjectOutputStream out = new ObjectOutputStream(bout);  
        out.writeObject(list);  
        out.close();  
        bout.close();  
  
        list.remove(2);  
  
        byte[] array = bout.toByteArray();  
  
        ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(array));  
        ArrayList<User> list2 = (ArrayList)in.readObject();  
        in.close();  
  
        for (int i = 0; i < list2.size(); i++) {  
            System.out.println(list2.get(i));  
        }  
    }  
}

// User{email='uni@example.com', name='신재윤', birthYear=1996}
// User{email='zzzzz@example.com', name='홍길동', birthYear=1986}
// User{email='asdfasdf@example.com', name='둘리', birthYear=1972}

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public class ObjectInputOutExam {  
    public static void main(String[] args) throws Exception {  
        User user1 = new User("uni@example.com", "신재윤", 1996);  
        User user2 = new User("zzzzz@example.com", "홍길동", 1986);  
        User user3 = new User("asdfasdf@example.com", "둘리", 1972);  
        ArrayList<User> list = new ArrayList<>();  
        list.add(user1);  
        list.add(user2);  
        list.add(user3);  
  
        ArrayList<User> list2 = copy(list);  
  
        for (int i = 0; i < list2.size(); i++) {  
            System.out.println(list2.get(i));  
        }  
    }  
  
    private static ArrayList<User> copy(ArrayList<User> list) throws IOException, ClassNotFoundException {  
        ByteArrayOutputStream bout = new ByteArrayOutputStream();  
        ObjectOutputStream out = new ObjectOutputStream(bout);  
        out.writeObject(list);  
        out.close();  
        bout.close();  
  
        byte[] array = bout.toByteArray();  
  
        ObjectInputStream in = new ObjectInputStream(new ByteArrayInputStream(array));  
        ArrayList<User> list2 = (ArrayList)in.readObject();  
        in.close();  
        return list2;  
    }  
}