Java FileReader neranda file'o

public class Pirmas {
   public static void main(String args[]) {
	File f = new File("duomenys.txt");
	if (f.exists())
	    System.out.println("afasf");
        if (f.canRead())
	    System.out.println("fafafa");
	FileReader fr = new FileReader(f);
   }
}

Zodziu, failas yra, isprintina ten tas zinutes, jei filereaderio nekuri, taciau kuriant filereaderi gaunam FileNotFoundException. Nenaudoju jokiu IDE, kompiliuoju is komandines eilutes, any ideas?

EDIT : ivilkus i try catch pradejo veikt, tiek as tos java ir temoku, bet gal galit paaiskint kas nors, kame cia reples?

Viskas labai paprasta - FileReader() klases konstruktorius yra nurodes, kad " throws FileNotFoundException", vadinasi, jeigu naudoji FileReader tu privalai bandyti pagauti ta klaida su try/catch arba nurodyti, kad metodas gali mesti si error pridedant siuo atveju "public static void main(String args[]) throws FileNotFoundException".

Priesingai nei kai kurios kitos programavimo kalbos, java yra itin griezta, kai kalbame apie tokius dalykus kaip errors.

Kuria JAVA cia kuri, SE, EE ar ME? :unsure:

JAVA ME sis failu nuskaitymui puikiai veikia kvieciant paprasciausia file.inside_read("failas.txt"):

// ================================================================================
//                            FAILU ATVERIMAS/IRASYMAS
// ================================================================================
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;

public class file
{
// ============================== FAILO ATVERIMAS (TARP JAR)
public String inside_read(String file_url)
{
 try
 {
 Reader in = new InputStreamReader(this.getClass().getResourceAsStream(file_url));

 StringBuffer temp = new StringBuffer(1024);
 char[] buffer = new char[1024];
 int read;
  while ((read=in.read(buffer, 0, buffer.length)) != -1)
  {
  temp.append(buffer, 0, read);
  }

 return temp.toString();
 }
 catch (IOException ex)
 {
 return null;
 }
}
}

Viskas labai paprasta - FileReader() klases konstruktorius yra nurodes, kad " throws FileNotFoundException", vadinasi, jeigu naudoji FileReader tu privalai bandyti pagauti ta klaida su try/catch arba nurodyti, kad metodas gali mesti si error pridedant siuo atveju "public static void main(String args[]) throws FileNotFoundException".

 

Priesingai nei kai kurios kitos programavimo kalbos, java yra itin griezta, kai kalbame apie tokius dalykus kaip errors.

Tavo tiesa. As ir pats kiek daug ant to C++ prisirasau vos paprasciausio lango trinimui, kad tik kuo aiskiau suprasciau ta klaida: :(

// ==========================================================================================
//                                       DELETE WINDOW
// ==========================================================================================
void delete_window(string window_name)
{
string error_value = ""; bool error_exists = false;

int window_index;
// ============================== SEARCH ARRAY INDEX
if (!error_exists)
{
window_index = window_name_get_index(window_name);
 if (window_index == -1)
 {
 error_value += "delete_window():\n";
 error_value += "Langas pavadinimu " + window_name + " nerastas tarp win32_window_array masyvu.\n";
 error_exists = true;
 }
}

// ============================== SEARCH HWND
if (!error_exists)
{
 if (IsWindow(win32_window_array_hwnd[window_index]))
 {
 error_value += "delete_window():\n";
 error_value += "Langas pavadinimu " + window_name + " turi neegzistuojanti HWND.\n";
 error_exists = true;
 }
}

// ============================== DELETE FROM SYSTEM
if (!error_exists)
{
 if (!DestroyWindow(win32_window_array_hwnd[window_index]))
 {
 error_value += "delete_window():\n";
 error_value += "Lange pavadinimu " + window_name + " negali istrinti HWND.\n";
 error_exists = true;
 }
 else if (!UnregisterClass(window_name.c_str(), program_hinstance))
 {
 error_value += "delete_window():\n";
 error_value += "Lange pavadinimu " + window_name + " negali istrinti klases.\n";
 error_exists = true;
 }
}

// ============================== DELETE FROM ARRAY
if (!error_exists)
{
win32_window_array_delete(window_index);
}

// ============================== ERROR EXISTS
if (error_exists)
{
alert(error_value);

 if (confirm("Vygditi priverstini istrinima?"))
 {
 error_value = "";

 error_value += "1. Masyva istrinti ";
  if (window_index != -1)
  {
  error_value += win32_window_array_delete(window_index)?"pavyko":"nepavyko";
  }
  else
  {
  error_value += "nepavyko (masyvo index nerastas)";
  }
 error_value += "\n";

 error_value += "2. Langa istrinti ";
  if (window_index != -1)
  {
  error_value += DestroyWindow(win32_window_array_hwnd[window_index])?"pavyko":"nepavyko";
  }
  else
  {
  error_value += "nepavyko (masyvo index nerastas)";
  }
 error_value += "\n";

 error_value += "3. Klase istrinti ";
 error_value += UnregisterClass(window_name.c_str(), program_hinstance)?"pavyko":"nepavyko";
 error_value += "\n";
 alert(error_value);
 }
}
}
// ==========================================================================================