Calculeaza lungimea unui sir de caractere

import java.io.BufferedReader;

import java.io.InputStreamReader;

class ReadConsole {

public static void main(String args[]) throws Exception {

InputStreamReader isr = new InputStreamReader(System.in);

BufferedReader br = new BufferedReader(isr);

String s;

while ((s = br.readLine()) != null) {

System.out.println(s.length());

}

isr.close();

}}

Crearea si scrierea intrun fisier txt

import java.io.*;
public class FileOutput {
public static void main(String[] args) {
FileOutputStream fos;
DataOutputStream dos;
try {
File file= new File("E:\\MyFile.txt");
fos = new FileOutputStream(file);
dos=new DataOutputStream(fos);
dos.writeInt(2333);
dos.writeChars("Hello");
} catch (IOException e) {
e.printStackTrace();
}
}
}

Crează un fisier txt

import java.io.File;
public class Main {
public static void main(String[] args) throws Exception {
File file = new File("E://demo.txt");
boolean blnCreated = false;
blnCreated = file.createNewFile();
System.out.println(blnCreated);
} }

Citeşte prima linie dintrun fişier

import java.io.DataInputStream;
import java.io.FileInputStream;
public class Main {
public static void main(String[] args) throws Exception{
FileInputStream fin = new FileInputStream("E:/experiment.txt");
DataInputStream din = new DataInputStream(fin);
//char ch = (char) din.readByte();
System.out.println(din.readLine());
din.close();
} }

Vedem daca un fisier are ceva scris in el sau nu

import java.io.File;
public class Main {
public static void main(String[] args) {
String filePath = "E:/experiment.txt";
File file = new File(filePath);
if (file.canWrite()) {
System.out.println("writable");
} else {
System.out.println("not writable");
} } }