错误：未报告的异常FileNotFoundException; 必须被抓住或宣布被抛出

您没有告诉编译器，如果文件不存在，则有可能抛出

FileNotFoundException

FileNotFoundException

试试这个

public static void main(String[] args) throws FileNotFoundException {    File file = new File ("file.txt");    file.getParentFile().mkdirs();    try    {        PrintWriter printWriter = new PrintWriter(file);        printWriter.println ("hello");        printWriter.close();}    catch (FileNotFoundException ex)      {        // insert pre to run when exception occurs    }}