reading input till EOF in java

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In C++ if I wish to read input till the EOF I can do it in the following manner

while(scanf("%d",&n))
{
    A[i]=n;
    i++;
}

I can then run this code as ./a.out < input.txt. What is the java equivalent of this code?

You can do this:

Scanner s = new Scanner(System.in);
while (s.hasNextInt()) {
    A[i] = s.nextInt();
    i++;
}

reading input till EOF in java, Learn about seven different ways to read a file line-by-line in Java (Scanner, File("examplefile.txt")); // read until end of file (EOF) while (scanner. way to read characters, arrays, and lines from a character-input stream. Java End-of-file. "In computing, End Of File (commonly abbreviated EOF) is a condition in a computer operating system where no more data can be read from a data source." — ( Wikipedia: End-of-file) The challenge here is to read lines of input until you reach EOF, then number and print all lines of content.

// assuming that reader is an instance of java.io.BufferedReader
String line = null;
while ((line = reader.readLine()) != null) {
    // do something with every line, one at a time
}

Let me know if you run into difficulties.

How to read a file line by line in Java (Example), readLine(); // do not forget to read next line ! } no special end case##. In this case you simply stop when you reach the end of file. It's very similar to  Java End-of-file. "In computing, End Of File (commonly abbreviated EOF) is a condition in a computer operating system where no more data can be read from a data source." — ( Wikipedia: End-of-file) The challenge here is to read lines of input until you reach EOF, then number and print all lines of content.

 import java.io.BufferedReader;
 import java.io.FileReader;

BufferedReader br = null;  
     br = new BufferedReader(new FileReader(file));
       while ((line = br.readLine()) != null) {              

     }

    //using Scanner class

    Scanner scanner = new Scanner(file);
    while (scanner.hasNextLine()) {
      String line = scanner.nextLine();
      System.out.println(line);
   }

how to take the input till the end of the last line, in java???, condition. If you are using readLine() method of BufferedReader, it returns null on the next read after the last data is read off the stream. In a non-Cygwin Windows program, Ctrl-Z on input triggers an end-of-file condition. In a Cygwin program, one that uses the Cygwin DLL, Ctrl-D on input triggers and end-of-file condition. (This can be reconfigured with the stty command, but you haven't done that.) It doesn't matter how the program is executed. It only matters how it was built.

Here is Java equivalent code using BufferedReader and FileReader classes.

  import java.io.BufferedReader;
  import java.io.FileReader;
  import java.io.IOException;

  public class SmallFileReader {
        public static void main(String[] args) throws IOException {
             BufferedReader br = new BufferedReader(new FileReader("Demo.txt"));
             String line=nul;
             while( (line=br.readLine()) != null) {
                    System.out.println(line);  
             }
  }
}

Java check end of file, Console class. It is used to provide a formatted prompt, then reads a single line of text from the console. readObject() doesn't return null at EOF. You could catch the EOFException and interpret it as EOF, but this would fail to detect distinguish a normal EOF from a file that has been truncated. A better approach would be to use some meta-data.

Here is Java equivalent code using BufferedReader and FileReader classes.

  import java.io.BufferedReader;
  import java.io.FileReader;
  import java.io.IOException;

  public class SmallFileReader {
        public static void main(String[] args) throws IOException {  

Option 1: String fileName = args[0]; BufferedReader br = new BufferedReader(new FileReader(fileName)); Option 2: BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); System.out.println("Enter a file name: "); String fileName = br.readLine();

             //BufferedReader br = new BufferedReader(new FileReader("Demo.txt"));
             String line=null;
             while( (line=br.readLine()) != null) {
                    System.out.println(line);  
             }
  }
}  

I made little modification to @Vallabh Code. @tom You can use the first option, if you want to input the file name through command line. java SmallFileReader Hello.txt Option 2 will ask you the file name when you run the file.

Java Console readline() Method with Examples, The challenge here is to read lines of input until you reach EOF, then number and print all lines of content. Hint: Java's Scanner.hasNext() method is helpful for this​  In Computer Science, a file is a resource used to record data discretely in a computer’s storage device. In Java, a resource is usually an object implementing the AutoCloseable interface. Reading files and resources have many usages: * Statistics, Analytics, and Reports * Machine Learning * Dealing with large text files or logs Sometimes, these files can be absurdly large, with gigabytes or

Java End-of-file Discussions | Java, reading input till EOF in java. eof in java geeksforgeeks what is eof in java java scanner read until end of line getline in java bufferedreader readline until eof Returns true if this Scanner has another token in its input. This method may block while waiting for input to scan. The Scanner does not advance past any input. Specified by: hasNext in interface Iterator<String> Returns: true if and only if this Scanner has another token. Throws: IllegalStateException - if this Scanner is closed

Java End-of-file, One of the easiest ways of reading a file line by line in Java could be A Scanner breaks its input into tokens using a delimiter pattern, which in our case is the as the null isn't equal to an empty line and the file will be read until the end. Enter an "end of file" marker. On UNIX and Mac OS that is (typically) CTRL+D, and on Windows CTRL+Z. That will result in hasNextLine() returning false. Enter some special input that is recognized by the program as meaning "I'm done". For instance, it could be an empty line, or some special value like "exit".

reading input till EOF in java, So I use an user defined fast input class to get faster input. The catch this time is that we need to read input till end of file. The class which I am  @iharob: from the link you posted: "The value EOF is returned if the end of input is reached before either the first successful conversion or a matching failure occurs. " (In the return values section.) – rici Dec 22 '14 at 17:50

Comments
  • Tried to google with your title? Search for Scanner or BufferedReader classes.
  • @GrijeshChauhan - try reading the question again.
  • @Perception sorry my mistake
  • What would happen if my file contains null as string ??? I am unable to read full file, can this be a reason ?
  • @I-droid - A Scanner processes input by dividing it into tokens based on occurrences of delimiter characters (white space by default). When you call Scanner#nextInt(), it expects the next token to match an integer regular expression; if it doesn't, the method will throw an exception. So having "null" in the file might very well be a problem for you, depending on how you are using the Scanner.
  • I like scanner method. Thanks
  • The trouble is I wouldn't know the name of the file in advance
  • @tom you can also enter through command line in java as it happens in C or C++.