请给出JAVA的PrintStream、PrintWriter和Scanner的案例

1. PrintStream案例：

import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.PrintStream;

public class PrintStreamDemo {
    public static void main(String[] args) {
        try {
            File file = new File("output.txt");
            FileOutputStream fos = new FileOutputStream(file);
            PrintStream ps = new PrintStream(fos);

            ps.println("Hello, PrintStream!");
            ps.println("This is a test.");

            ps.close();
            fos.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

2. PrintWriter案例：

import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;

public class PrintWriterDemo {
    public static void main(String[] args) {
        try {
            File file = new File("output.txt");
            PrintWriter pw = new PrintWriter(file);

            pw.println("Hello, PrintWriter!");
            pw.println("This is a test.");

            pw.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

3. Scanner案例：

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

public class ScannerDemo {
    public static void main(String[] args) {
        try {
            File file = new File("input.txt");
            Scanner scanner = new Scanner(file);

            while (scanner.hasNextLine()) {
                String line = scanner.nextLine();
                System.out.println(line);
            }

            scanner.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

这些案例分别演示了PrintStream、PrintWriter和Scanner的用法。PrintStream和PrintWriter可以用来向文件或控制台输出内容，Scanner可以用来从文件或控制台读取内容。