不同的方法需要匯入不同的包，使用Ctrl+Shift+O導包即可。

import java.io.BufferedReader;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStream;
import java.util.Scanner;

public class ReadText {
	// 方法一
	public static void f1() throws FileNotFoundException {
		InputStream is = System.in;
		System.setIn(new FileInputStream("檔名.txt"));
		Scanner scanner = new Scanner(System.in);
		while (scanner.hasNextLine())
			System.out.println(scanner.nextLine());
		
		System.setIn(is);
	}

	// 方法二
	public static void f2() throws FileNotFoundException {
		Scanner scanner = new Scanner(new FileInputStream("檔名.txt"));
		while (scanner.hasNextLine())
			System.out.println(scanner.nextLine());
	}

	// 方法三
    // 請注意使用BufferedReader讀取檔案，如果讀取不到下一行繼續輸出則會報錯
	public static void f3() throws IOException {

		BufferedReader bReader = new BufferedReader(new FileReader(new File(
				"檔名.txt")));
		String s = bReader.readLine();
		while (s != null) {
			System.out.println(s);
			s = bReader.readLine();
		}
	}

}