Поток Java 8 – Чтение файла строка за строкой

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package com.mkyong.java8;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.stream.Stream;

public class TestReadFile {

	public static void main(String args[]) {

		String fileName = "c://lines.txt";

		//read file into stream, try-with-resources
		try (Stream stream = Files.lines(Paths.get(fileName))) {

			stream.forEach(System.out::println);

		} catch (IOException e) {
			e.printStackTrace();
		}

	}

}

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package com.mkyong.java8;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class TestReadFile2 {

	public static void main(String args[]) {

		String fileName = "c://lines.txt";
		List list = new ArrayList<>();

		try (Stream stream = Files.lines(Paths.get(fileName))) {

			//1. filter line 3
			//2. convert all content to upper case
			//3. convert it into a List
			list = stream
					.filter(line -> !line.startsWith("line3"))
					.map(String::toUpperCase)
					.collect(Collectors.toList());

		} catch (IOException e) {
			e.printStackTrace();
		}

		list.forEach(System.out::println);

	}

}

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package com.mkyong.java8;

import java.io.BufferedReader;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

public class TestReadFile3{

	public static void main(String args[]) {

		String fileName = "c://lines.txt";
		List list = new ArrayList<>();

		try (BufferedReader br = Files.newBufferedReader(Paths.get(fileName))) {

			//br returns as stream and convert it into a List
			list = br.lines().collect(Collectors.toList());

		} catch (IOException e) {
			e.printStackTrace();
		}
	
		list.forEach(System.out::println);

	}

}

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package com.mkyong.core;

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

public class TestReadFile4{

	public static void main(String args[]) {

		String fileName = "c://lines.txt";

		try (BufferedReader br = new BufferedReader(new FileReader(fileName))) {

			String line;
			while ((line = br.readLine()) != null) {
				System.out.println(line);
			}

		} catch (IOException e) {
			e.printStackTrace();
		}

	}

}

package com.mkyong.core;

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

public class TestReadFile5 {

	public static void main(String args[]) {

		String fileName = "c://lines.txt";

		try (Scanner scanner = new Scanner(new File(fileName))) {

			while (scanner.hasNext()){
				System.out.println(scanner.nextLine());
			}

		} catch (IOException e) {
			e.printStackTrace();
		}

	}

}