用PrintStream向文件输入内容

import java.io.*;
public class Main {
    public static void main(String[] args) throws FileNotFoundException
    {
        PrintStream ps = new PrintStream(new FileOutputStream("work.txt"));
        //改变输出流，输出到work.txt文件
        System.setOut(ps);
        //用System.out.println()即可将内容输出到文件中
        System.out.println(12);
        double d = 2.36;
        System.out.println(d);
        System.out.print("可以吗");
        System.out.println("很厉害的样子");
    }
}

结果