Java Input/Output

import java.io.File;

public class Program {
    public static void main(String[] args) {
        // определяем объект для каталога
        File dir = new File("C://SomeDir");
        // если объект представляет каталог
        if (dir.isDirectory()) {
            // получаем все вложенные объекты в каталоге
            for (File item : dir.listFiles()) {
                if (item.isDirectory()) {
                    System.out.println(item.getName() + "  \t folder");
                } else {
                    System.out.println(item.getName() + "\t file");
                }
            }
        }
    }
}

import java.io.File;

public class Program {
    public static void main(String[] args) {
        // определяем объект для каталога
        File dir = new File("C://SomeDir//NewDir");
        boolean created = dir.mkdir();
        if (created) {
            System.out.println("Folder has been created");
        }
        // переименуем каталог
        File newDir = new File("C://SomeDir//NewDirRenamed");
        dir.renameTo(newDir);
        // удалим каталог
        boolean deleted = newDir.delete();
        if (deleted) {
            System.out.println("Folder has been deleted");
        }
    }
}

import java.io.File;
import java.io.IOException;

public class Program {
    public static void main(String[] args) {
        // определяем объект для каталога
        File myFile = new File("C://SomeDir//notes.txt");
        System.out.println("File name: " + myFile.getName());
        System.out.println("Parent folder: " + myFile.getParent());
        if (myFile.exists()) {
            System.out.println("File exists");
        } else {
            System.out.println("File not found");
        }

        System.out.println("File size: " + myFile.length());
        if (myFile.canRead()) {
            System.out.println("File can be read");
        } else {
            System.out.println("File can not be read");
        }

        if (myFile.canWrite()) {
            System.out.println("File can be written");
        } else {
            System.out.println("File can not be written");
        }
        // создадим новый файл
        File newFile = new File("C://SomeDir//MyFile");
        try {
            boolean created = newFile.createNewFile();
            if (created) {
                System.out.println("File has been created");
            }
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

import java.io.FileOutputStream;
import java.io.IOException;

public class Program {
    public static void main(String[] args) {
        String text = "Hello world!"; // строка для записи
        try (FileOutputStream fos = new FileOutputStream("C://SomeDir//notes.txt")) {
            byte[] buffer = text.getBytes(); // перевод строки в байты
            fos.write(buffer, 0, buffer.length);
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
        System.out.println("The file has been written");
    }
}

fos.write(buffer[0]); // запись первого байта

import java.io.FileInputStream;
import java.io.IOException;

public class Program {
    public static void main(String[] args) {
        try (FileInputStream fin = new FileInputStream("C://SomeDir//notes.txt")) {
            System.out.printf("File size: %d bytes \n", fin.available());
            int i = -1;
            while ((i = fin.read()) != -1) {
                System.out.print((char) i);
            }
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

while ((i = fin.read()) != -1) {
}

byte[] buffer = new byte[fin.available()]; // считаем файл в буфер
fin.read(buffer, 0, fin.available());
System.out.println("File data:");
for (int i = 0; i < buffer.length; i++) {
    System.out.print((char) buffer[i]);
}

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

public class Program {
    public static void main(String[] args) {
        try (FileInputStream fin = new FileInputStream("C://SomeDir//notes.txt");
             FileOutputStream fos = new FileOutputStream("C://SomeDir//notes_new.txt")) {
            byte[] buffer = new byte[fin.available()]; // считываем буфер
            fin.read(buffer, 0, buffer.length); // записываем из буфера в файл
            fos.write(buffer, 0, buffer.length);
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

import java.io.ByteArrayInputStream;

public class Program {
    public static void main(String[] args) {
        byte[] array1 = new byte[] {1, 3, 5, 7};
        ByteArrayInputStream byteStream1 = new ByteArrayInputStream(array1);
        int b;
        while ((b = byteStream1.read()) != -1) {
            System.out.println(b);
        }
        String text = "Hello world!";
        byte[] array2 = text.getBytes();
        ByteArrayInputStream byteStream2 = new ByteArrayInputStream(array2, 0, 5); // считываем 5 символов
        int c;
        while ((c = byteStream2.read()) != -1) {
            System.out.println((char) c);
        }
    }
}

import java.io.ByteArrayOutputStream;

public class Program {
    public static void main(String[] args) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        String text = "Hello Wolrd!";
        byte[] buffer = text.getBytes();
        try {
            baos.write(buffer);
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }
        System.out.println(baos.toString()); // превращаем массив байтов в строку
        byte[] array = baos.toByteArray(); // получаем массив байтов и выводим по символьно
        for (byte b : array) {
            System.out.print((char) b);
        }
        System.out.println();
    }
}

ByteArrayOutputStream baos = new ByteArrayOutputStream();
String text = "Hello Wolrd!";
byte[] buffer = text.getBytes();
try {
    baos.write(buffer);
} catch (Exception ex) {
    System.out.println(ex.getMessage());
}
try (FileOutputStream fos = new FileOutputStream("hello.txt")) {
    baos.writeTo(fos);
} catch (IOException e) {
    System.out.println(e.getMessage());
}

import java.io.BufferedInputStream;
import java.io.ByteArrayInputStream;

public class Program {
    public static void main(String[] args) {
        String text = "Hello world!";
        byte[] buffer = text.getBytes();
        ByteArrayInputStream in = new ByteArrayInputStream(buffer);
        try (BufferedInputStream bis = new BufferedInputStream(in)) {
            int c;
            while ((c = bis.read()) != -1) {
                System.out.print((char) c);
            }
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
        System.out.println();
    }
}

import java.io.*;

public class Program {
    public static void main(String[] args) {
        Person tom = new Person("Tom", 34, 1.68, false);
        // запись в файл
        try (DataOutputStream dos = new DataOutputStream(new FileOutputStream("data.bin"))) {
            dos.writeUTF(tom.name);
            dos.writeInt(tom.age);
            dos.writeDouble(tom.height);
            dos.writeBoolean(tom.married);
            System.out.println("File has been written");
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }

        // обратное считывание из файла
        try (DataInputStream dos = new DataInputStream(new FileInputStream("data.bin"))) {
            String name = dos.readUTF();
            int age = dos.readInt();
            double height = dos.readDouble();
            boolean married = dos.readBoolean();
            System.out.printf("Name: %s  Age: %d  Height: %f  Married: %b", name, age, height, married);
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

class Person {
    public String name;
    public int age;
    public double height;
    public boolean married;

    public Person(String n, int a, double h, boolean m) {
        this.name = n;
        this.height = h;
        this.age = a;
        this.married = m;
    }
}

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.PrintStream;

public class Program {
    public static void main(String[] args) {
        String text = "Привет мир!"; // строка для записи
        try (FileOutputStream fos = new FileOutputStream("C://SomeDir//notes3.txt");
             PrintStream printStream = new PrintStream(fos)) {
            printStream.println(text);
            System.out.println("Запись в файл произведена");
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

import java.io.IOException;
import java.io.PrintStream;

public class Program {
    public static void main(String[] args) {
        try (PrintStream printStream = new PrintStream("notes3.txt")) {
            printStream.print("Hello World!");
            printStream.println("Welcome to Java!");
            printStream.printf("Name: %s Age: %d \n", "Tom", 34);
            String message = "PrintStream";
            byte[] messageToBytes = message.getBytes();
            printStream.write(messageToBytes);
            System.out.println("The file has been written");
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

Hello World!Welcome to Java!
Name: Tom Age: 34
PrintStream

try (PrintWriter pw = new PrintWriter(System.out)) {
    pw.println("Hello world!");
}

import java.io.FileWriter;
import java.io.IOException;

public class Program {
    public static void main(String[] args) {
        try (FileWriter writer = new FileWriter("notes3.txt", false)) {
            String text = "Hello Gold!";
            writer.write(text); // запись всей строки
            writer.append('\n'); // запись одного символа
            writer.append('E');
            writer.flush();
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;

public class Program {
    public static void main(String[] args) {
        try (BufferedWriter bw = new BufferedWriter(new FileWriter("notes4.txt"))) {
            String text = "Hello  World!\nHey! Teachers! Leave them kids alone.";
            bw.write(text);
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

import java.io.BufferedReader;
import java.io.FileReader;
import java.io.IOException;

public class Program {
    public static void main(String[] args) {
        try (BufferedReader br = new BufferedReader(new FileReader("notes4.txt"))) {
            // чтение посимвольно
            int c;
            while ((c = br.read()) != -1) {
                System.out.print((char) c);
            }
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

try (BufferedReader br = new BufferedReader(new FileReader("notes4.txt"))) {
    //чтение построчно
    String s;
    while ((s = br.readLine()) != null) {
        System.out.println(s);
    }
} catch (IOException ex) {
    System.out.println(ex.getMessage());
}

import java.io.*;

public class Program {
    public static void main(String[] args) {
        try (BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
             BufferedWriter bw = new BufferedWriter(new FileWriter("notes5.txt"))) {
            // чтение построчно
            String text;
            while (!(text = br.readLine()).equals("ESC")) {
                bw.write(text + "\n");
                bw.flush();
            }
        } catch (IOException ex) {
            System.out.println(ex.getMessage());
        }
    }
}

ObjectOutputStream(OutputStream out)

import java.io.FileOutputStream;
import java.io.ObjectOutputStream;
import java.io.Serializable;

public class Program {
    public static void main(String[] args) {
        try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream("person.dat"))) {
            Person p = new Person("Sam", 33, 178, true);
            oos.writeObject(p);
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }
    }
}

class Person implements Serializable {
    private String name;
    private int age;
    private double height;
    private boolean married;

    Person(String n, int a, double h, boolean m) {
        name = n;
        age = a;
        height = h;
        married = m;
    }

    String getName() {
        return name;
    }

    int getAge() {
        return age;
    }

    double getHeight() {
        return height;
    }

    boolean getMarried() {
        return married;
    }
}

ObjectInputStream(InputStream in)

import java.io.FileInputStream;
import java.io.ObjectInputStream;

public class Program {
    public static void main(String[] args) {
        try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream("person.dat"))) {
            Person p = (Person) ois.readObject();
            System.out.printf("Name: %s \t Age: %d \n", p.getName(), p.getAge());
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }
    }
}

import java.io.*;
import java.util.ArrayList;

public class Program {
    //@SuppressWarnings("unchecked")
    public static void main(String[] args) {
        String filename = "people.dat";
        // создадим список объектов, которые будем записывать
        ArrayList<Person> people = new ArrayList<Person>();
        people.add(new Person("Tom", 30, 175, false));
        people.add(new Person("Sam", 33, 178, true));

        try (ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(filename))) {
            oos.writeObject(people);
            System.out.println("File has been written");
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }

        // десериализация в новый список
        ArrayList<Person> newPeople = new ArrayList<Person>();
        try (ObjectInputStream ois = new ObjectInputStream(new FileInputStream(filename))) {
            newPeople = ((ArrayList<Person>) ois.readObject());
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }

        for (Person p : newPeople) {
            System.out.printf("Name: %s \t Age: %d \n", p.getName(), p.getAge());
        }
    }
}

class Person implements Serializable {
    private String name;
    private int age;
    private double height;
    private boolean married;

    public Person(String n, int a, double h, boolean m) {
        this.name = n;
        this.age = a;
        this.height = h;
        this.married = m;
    }

    public String getName() {
        return this.name;
    }

    public int getAge() {
        return this.age;
    }

    public double getHeight() {
        return this.height;
    }

    public boolean getMarried() {
        return this.married;
    }
}

import java.io.Serializable;

class Person implements Serializable {
    private String name;
    private int age;
    private transient double height;
    private transient boolean married;

    public Person(String n, int a, double h, boolean m) {
        this.name = n;
        this.age = a;
        this.height = h;
        this.married = m;
    }

    public String getName() {
        return this.name;
    }

    public int getAge() {
        return this.age;
    }

    public double getHeight() {
        return this.height;
    }

    public boolean getMarried() {
        return this.married;
    }
}

ZipOutputStream(OutputStream out)

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipOutputStream;

public class Program {
    public static void main(String[] args) {
        String filename = "C:\\SomeDir\\notes.txt";
        try (ZipOutputStream zout = new ZipOutputStream(new FileOutputStream("C:\\SomeDir\\output.zip"));
             FileInputStream fis = new FileInputStream(filename);) {
            ZipEntry entry1 = new ZipEntry("notes.txt");
            zout.putNextEntry(entry1);
            // считываем содержимое файла в массив byte
            byte[] buffer = new byte[fis.available()];
            fis.read(buffer);
            // добавляем содержимое к архиву
            zout.write(buffer);
            // закрываем текущую запись для новой записи
            zout.closeEntry();
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }
    }
}

ZipInputStream(InputStream in)

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.zip.ZipEntry;
import java.util.zip.ZipInputStream;

public class Program {
    public static void main(String[] args) {
        try (ZipInputStream zin = new ZipInputStream(new FileInputStream("C:\\SomeDir\\output.zip"))) {
            ZipEntry entry;
            String name;
            long size;
            while ((entry = zin.getNextEntry()) != null) {
                name = entry.getName(); // получим название файла
                size = entry.getSize();  // получим его размер в байтах
                System.out.printf("File name: %s \t File size: %d \n", name, size);
                // распаковка
                FileOutputStream fout = new FileOutputStream("C:\\somedir\\new" + name);
                for (int c = zin.read(); c != -1; c = zin.read()) {
                    fout.write(c);
                }
                fout.flush();
                zin.closeEntry();
                fout.close();
            }
        } catch (Exception ex) {
            System.out.println(ex.getMessage());
        }
    }
}