IO

Question 1

nacteni file.txt do input streamu

Answer 1

InputStream in = new FileInputStream(“file.txt”);

Question 2

output stream to file.txt

Answer 2

OutputStream out = new FileOutputStream(“file.txt”);

Question 3

FileInputStream - co umi

Answer 3

Umi cist z file do inputStream (v bytech)

Question 4

InputStreamReader - co umi

Answer 4

prevest stream bytu na stream charu

Question 5

BufferedReader - co umi

Answer 5

precist radek z charoveho streamu: br.readLine()

Question 6

FileOutputStream - co umi

Answer 6

umi ze streamu bytu zapisovat do souboru

Question 7

OutputStreamWriter

Answer 7

prevadi stream charu na stream bytu

Question 8

BufferedWriter - co umi

Answer 8

umi zapisovat do charoveho streamu: bw.println(“x”)

Question 9

Zapis radku “x” do souboru file.txt

Answer 9

try (BW out = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(“file.txt”)))) {
out.println(“x”);
}

Question 10

Vypis radku ze souboru file.txt na stdout

Answer 10

try (BR in = new BufferedReader(new InputStreamReader(new FileInputStream(“file.txt”)))) {
String line;
while (line = in.readLine() != null) {
sout(line);
}
}

Question 11

Alternativa k new InputStreamReader(new FileInputStream(file))

Answer 11

new FileReader(file, charset)

Question 12

Alternativa k new OutputStreamWriter(new FileOutputStream(file))

Answer 12

new FileWriter(file, charset)

Question 13

Jake mame tridy pro zapis/cteni mezi streamy

Answer 13

PipedInput/OutputStream
PipedReader/Writer

Question 14

Jake mame tridy pro zapis/cteni objektu do streamu

Answer 14

ObjectInput/OutputStream

Question 15

vytvor charset pro UTF-8

Answer 15

Charset.forName(“UTF-8”)

Question 16

Nacteni vsech radku ze souboru file.txt do seznamu

Answer 16

Files.readAllLines(Path.of(“file.txt”));

Question 17

Jak se nactou byty z readeru do bufferu? (2)

Answer 17

read(buffer)
read(buffer, offset, length) - kolik se preskoci a kolik vezme
vraci pocet nactenych bytu (nebo -1)

Question 18

Jak se oznaci pozice ve streamu?

Answer 18

is.mark(5)

Question 19

Jak se input stream prevede na output stream

Answer 19

is.transferTo(os)

Question 20

Output writer - jak se zapise z bufferu (byte[]) do streamu

Answer 20

os.write(buffer, offset, length) - offset je u bufferu

Question 21

Co dela flush na streamu?

Answer 21

Zapise na vystup a smaze frontu

Question 22

Metody zmeny pozice v binarnim streamu (2)

Answer 22

is.skip(5)
is.reset()

Question 23

Jak zjistim zbyvajici pocet bytu ve streamu?

Answer 23

is.available()

Question 24

Checky: input stream - lze oznacovat pozici?
textovy input stream - lze cist?

Answer 24

is.markSupported()
is.ready()

Question 25

Soubor file.txt - zapis do souboru file2.txt (binarne)

Answer 25

try (InputStream is = new FileInputStream(“file.txt”);
OutputStream os = new FileOutputStream(“file2.txt”)) {
byte[] bytes = new byte[1024];
while ((length = is.read(bytes)) != -1) {
os.write(bytes, 0, length);
}
}

Question 26

Trida pro cteni bytu ze souboru do streamu

Answer 26

FileInputStream

Question 27

Trida pro prevod input streamu s byty na input stream se znaky

Answer 27

InputStreamReader

Question 28

Trida pro cteni ze znakoveho input streamu po radcich

Answer 28

BufferedReader

Question 29

Trida pro zapis streamu bytu do souboru

Answer 29

FileOutputStream

Question 30

Trida pro prevod output streamu charu na output stream bytu

Answer 30

OutputStreamWriter

Question 31

Trida pro zapis do znakoveho output streamu po radcich

Answer 31

PrintWriter

Question 32

InputStream pro stdin, PrintWritery pro stdout, a stderr

Answer 32

System.out, System.in, System.err

Question 33

Jak se cte ze stdin? dokud tam neni hodnota exit

Answer 33

Scanner s = new Scanner(System.in);
String txt;
while ((txt = s.nextLine()) != “exit”) {
sout(txt);
}

Question 34

Jak zapisu do konzole “str”?

Answer 34

System.console().writer().println(“str”);

Question 35

Jak prectu z konzole radek?
Co vraci, kdyz dosly radky?

Answer 35

String line = System.console().reader().readLine()
null