Programming Tutorials

readLine( ) to read strings from console input

By: Kamini  

To read a string from the keyboard, use the version of readLine( ) that is a member of the BufferedReader class. Its general form is shown here:

String readLine( ) throws IOException

As you can see, it returns a String object. The following program demonstrates BufferedReader and the readLine( ) method; the program reads and displays lines of text until you enter the word "stop":

// Read a string from console using a BufferedReader.
import java.io.*;
class BRReadLines {
public static void main(String args[])
throws IOException
{
// create a BufferedReader using System.in
BufferedReader br = new BufferedReader(new
InputStreamReader(System.in));
String str;
System.out.println("Enter lines of text.");
System.out.println("Enter 'stop' to quit.");
do {
str = br.readLine();
System.out.println(str);
} while(!str.equals("stop"));
}
}

The next example creates a tiny text editor. It creates an array of String objects and then reads in lines of text, storing each line in the array. It will read up to 100 lines or until you enter "stop". It uses a BufferedReader to read from the console.

// A tiny editor.
import java.io.*;
class TinyEdit {
public static void main(String args[])
throws IOException
{
// create a BufferedReader using System.in
BufferedReader br = new BufferedReader(new
InputStreamReader(System.in));
String str[] = new String[100];
System.out.println("Enter lines of text.");
System.out.println("Enter 'stop' to quit.");
for(int i=0; i<100; i++) {
str[i] = br.readLine();
if(str[i].equals("stop")) break;
}
System.out.println("\\nHere is your file:");
// display the lines
for(int i=0; i<100; i++) {
if(str[i].equals("stop")) break;
System.out.println(str[i]);
}
}
}

Here is a sample run:

Enter lines of text.
Enter 'stop' to quit.
This is line one.
This is line two.
Java makes working with strings easy.
Just create String objects.
stop
Here is your file:
This is line one.
This is line two.
Java makes working with strings easy.
Just create String objects.

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