FileWriter

 package file;

 import java.io.File;
 import java.io.FileWriter;
 import java.io.IOException;

 public class Demo6 {
     public static void main(String[] args) throws IOException {
         writeTest1();
     }

     public static void writeTest1() throws IOException {
         File file = new File("F:\\2.txt");
         FileWriter fileWriter = new FileWriter(file);
 //        FileWriter fileWriter = new FileWriter(file,true);//如果追加，使用FileWriter(file,true)
         //准备数据，写出
         String data = "测试123数据";
         fileWriter.write(data);
         //关闭资源
 //        fileWriter.flush();
         fileWriter.close();

     }
 }