InputStreamReader Class
The InputStreamReader class reads characters from a byte input stream. It reads bytes and decodes them into characters using a specified charset. The decoding layer transforms bytes to chars according to an encoding standard . There are many available encodings to choose from.
InputStreamReader class performs two tasks:
- Read input stream of keyboard.
- Convert byte streams to character streams.
The following Java program obtain an InputStreamReader from keyboard
import java.util.*;
import java.io.*;
public class TestClass{
public static void main( String[] args ){
try {
InputStreamReader isReader = new InputStreamReader(System.in);
BufferedReader bReader=new BufferedReader(isReader);
System.out.println("Enter anything......");
String data=bReader.readLine();
System.out.println("You Entered.... "+data);
} catch (IOException e) {
e.printStackTrace();
}
}
}
The following Java program obtain an InputStreamReader from a file
import java.util.*;
import java.io.*;
public class TestClass{
public static void main( String[] args ){
try {
InputStream is = new FileInputStream("d:\\test.txt");
Reader isr = new InputStreamReader(is);
int data = isr.read();
while(data != -1){
data = isr.read();
char chr = (char) data;
System.out.print(chr);
}
isr.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
How do I convert a String to an InputStream in Java?
ByteArrayInputStream does the trick from Java 1.4
InputStream is = new ByteArrayInputStream(inputString.getBytes(StandardCharsets.UTF_8));
From Java 1.7, StandardCharsets defines constants for Charset including UTF-8 . You should include import java.nio.charset.StandardCharsets; in your Java file. Note that this assumes that you want an InputStream that is a stream of bytes that represent your original string encoded as UTF-8 .
The following Java program read a String as InputStream.
import java.util.*;
import java.io.*;
import java.nio.charset.StandardCharsets;
public class TestClass{
public static void main( String[] args ){
try {
String inputString = "This is a test !! ";
InputStream is = new ByteArrayInputStream(inputString.getBytes(StandardCharsets.UTF_8));
Reader isr = new InputStreamReader(is);
int data = isr.read();
while(data != -1){
data = isr.read();
char chr = (char) data;
System.out.print(chr);
}
isr.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
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