OCJP IO Dates and Formatting

Dates.java

import java.text.DateFormat;
import java.util.*;

public class Dates {
	private static Date date = new Date((long) 1e12);
	private static Locale locale = new Locale("pl", "GB");
	private static Calendar calendar = Calendar.getInstance(locale);
	private static DateFormat dateFormatter = DateFormat.getDateInstance(
			DateFormat.FULL, locale);

	public static void main(String[] args) {
		System.out.println(date);
		System.out.println(dateFormatter.format(date));
		calendar.setTime(date);
		System.out.println("The week in " + locale.getDisplayCountry()
				+ " locale starts at day: " + calendar.getFirstDayOfWeek());
		// no such method
		// locale.setLocale(Locale.US);

		calendar.add(Calendar.DAY_OF_MONTH, 25);
		System.out.println(calendar.getTime());
		calendar.setTime(date);
		calendar.roll(Calendar.DAY_OF_MONTH, 25);
		System.out.println(calendar.getTime());

		calendar.add(Calendar.DAY_OF_MONTH, -3);
	}
}

FileIO.java

import java.io.*;

public class FileIO {
	public static void unbufferedWrite(String filename) {
		File file = new File(filename);
		try {
			FileWriter writer = new FileWriter(file);
			writer.write("hello\nworld\n");
			writer.flush();
			writer.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static void unbufferedRead(String filename) {
		File file = new File(filename);
		try {
			FileReader reader = new FileReader(file);
			System.out.println("encoding: " + reader.getEncoding());
			char[] cbuf = new char[50];
			System.out.println("read: " + reader.read(cbuf) + " bytes");
			for (char c : cbuf) {
				System.out.print(c);
			}
			reader.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static void bufferedWrite(String filename) {
		File file = new File(filename);
		FileWriter writer;
		try {
			writer = new FileWriter(file);
		} catch (IOException e) {
			e.printStackTrace();
			return;
		}
		BufferedWriter bw = new BufferedWriter(writer);
		try {
			bw.write("hello");
			bw.newLine();
			bw.write("world");
			bw.newLine();
			bw.flush();
			bw.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}

	public static void bufferedRead(String filename) {
		File file = new File(filename);
		FileReader reader;
		try {
			reader = new FileReader(file);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
			return;
		}
		BufferedReader bf = new BufferedReader(reader);
		try {
			String line;
			while ((line = bf.readLine()) != null) {
				System.out.println(line);
			}
			bf.close();
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	
	public static void printWriterUse(String filename) {
		File file = new File(filename);
		PrintWriter printWriter;
		try {
			printWriter = new PrintWriter(file);
		} catch (FileNotFoundException e) {
			e.printStackTrace();
			return;
		}
		printWriter.println("hello");
		printWriter.format("world%d", 2);
		printWriter.flush();
		printWriter.close();
		
	}
	
	public static void fileOperations() {
		File dir = new File("newDir");
		dir.mkdir();
		try {
			System.out.println(dir.getCanonicalFile());
		} catch (IOException e) {
			e.printStackTrace();
		}
		if (dir.isDirectory()) {
			System.out.println("is a directory");
		}
		File file = new File(dir, "newFile");
		try {
			if(file.createNewFile()) {
				System.out.println("File: " + file.getName() + " created");
			}
		} catch (IOException e) {
			e.printStackTrace();
		}
		File rFile = new File(dir, "newFile2");
		if(file.renameTo(rFile)) {
			System.out.println("File: " + file.getName() + " renamed");
		}
		System.out.println("Listng all files in "+dir.getAbsolutePath());
		for (String f : dir.list()) {
			System.out.println(f);
		}
		System.out.println("Deleting " + dir.getName());
		System.out.println("Deletion succeded: " + dir.delete());
		System.out.println("Deleting all files in " + dir.getName());
		for(File f : dir.listFiles()) {
			f.delete();
		}
		System.out.println("Deleting " + dir.getName());
		System.out.println("Deletion succeded: " + dir.delete());
	}

	public static void main(String[] args) {
		String filename = "ocjpIOTest.txt";
		unbufferedWrite(filename);
		unbufferedRead(filename);
		
		bufferedWrite(filename);
		
		printWriterUse(filename);

		bufferedRead(filename);
		
		fileOperations();
	}
}

Formatting.java

import java.util.IllegalFormatException;

public class Formatting {
	public static void main(String[] args) {
		int i1 = -123;
		int i2 = 12345;
		System.out.printf(">%1$(7d< \n", i1);
		System.out.printf(">%0,7d< \n", i2);
		System.out.printf(">%+-7d< \n", i2);
		try {
			System.out.printf(">%d<", 12.3);
		} catch (IllegalFormatException e) {
			e.printStackTrace();
		}
	}
}

Locales.java

import java.util.Locale;

public class Locales {
	private static Locale localeBR = new Locale("pt", "BR"); // Brazil
	private static Locale localeDK = new Locale("dk", "DK"); // Denmark
	private static Locale localeIT = new Locale("it", "IT"); // Italy

	public static void main(String[] args) {
		System.out.println(localeBR.getDisplayCountry());
		System.out.println(localeBR.getDisplayCountry(localeBR));
		System.out.println(localeBR.getDisplayCountry(localeDK));
		System.out.println(localeBR.getDisplayCountry(localeIT));

		System.out.println();

		System.out.println(localeBR.getDisplayLanguage());
		System.out.println(localeBR.getDisplayLanguage(localeBR));
		System.out.println(localeBR.getDisplayLanguage(localeDK));
		System.out.println(localeBR.getDisplayLanguage(localeIT));
	}
}

NumberFormatting.java

import java.text.NumberFormat;
import java.util.Locale;

public class NumberFormatting {
	private static Locale localeGB = new Locale("en", "GB");
	private static Locale localeFR = Locale.FRANCE;

	public static void main(String[] args) {
		float num = 1345.789F;

		// NumberFormat is abstract
		// NumberFormat numberFormat = new NumberFormat();
		NumberFormat numberFormat = NumberFormat.getInstance();
		NumberFormat numberFormatGB = NumberFormat.getInstance(localeGB);
		NumberFormat numberFormatFR = NumberFormat.getInstance(localeFR);
		System.out.println(numberFormat.format(num));
		System.out.println(numberFormatGB.format(num));
		System.out.println(numberFormatFR.format(num));

		NumberFormat currencyFormat = NumberFormat.getCurrencyInstance();
		NumberFormat currencyFormatGB = NumberFormat
				.getCurrencyInstance(localeGB);
		NumberFormat currencyFormatFR = NumberFormat
				.getCurrencyInstance(localeFR);

		System.out.println(currencyFormat.format(num));
		System.out.println(currencyFormatGB.format(num));
		System.out.println(currencyFormatFR.format(num));
	}
}

Patterns.java

import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;


public class Paterns {
	private static String string1 = "acz123u78 ou";
	
	public static void main(String[] args) {
		Pattern p = Pattern.compile("\\d+");
		Matcher m = p.matcher(string1);
		System.out.println("String: " + string1);
		printMatcher(m);
		printMatcher(Pattern.compile("\\w+").matcher(string1));
		printMatcher(Pattern.compile("\\d\\s").matcher(string1));
		printMatcher(Pattern.compile(".*?u").matcher(string1)); //reluctant
		printMatcher(Pattern.compile("o?").matcher(string1)); //greedy 
		
		Scanner s = new Scanner(string1);
		System.out.println(s.findInLine(p));
		System.out.println(s.findInLine(p));
		System.out.println(s.findInLine(p));
	}
	
	private static void printMatcher(Matcher m) {
		System.out.println("Pattern: " + m.pattern().pattern());
		while(m.find()) {
			System.out.println("startsAt:" + m.start() + " matches:\"" + m.group() + "\"");
		}
		System.out.println();
	}
}

UsingConsole.java

import java.io.Console;
import java.util.Arrays;

public class UsingConsole {
	public static void main(String[] args) {
		Console c = System.console();
		c.printf("Please enter your login:");
		String login = c.readLine();
		c.printf("Please enter you password:");
		char[] pass = c.readPassword();
		if (Arrays.equals(pass, "pass".toCharArray())) {
			c.printf("Welcome %s!\n", login);
		} else {
			c.printf("Sorry, you're not welcome here.\n");
		}
	}
}