How to Convert a String to an Inputstream in Java

How do I convert a String to an InputStream in Java?

Like this:

InputStream stream = new ByteArrayInputStream(exampleString.getBytes(StandardCharsets.UTF_8));

Note that this assumes that you want an InputStream that is a stream of bytes that represent your original string encoded as UTF-8.

For versions of Java less than 7, replace StandardCharsets.UTF_8 with "UTF-8".

How do I read / convert an InputStream into a String in Java?

A nice way to do this is using Apache commons IOUtils to copy the InputStream into a StringWriter... something like

StringWriter writer = new StringWriter();
IOUtils.copy(inputStream, writer, encoding);
String theString = writer.toString();

or even

// NB: does not close inputStream, you'll have to use try-with-resources for that
String theString = IOUtils.toString(inputStream, encoding); 

Alternatively, you could use ByteArrayOutputStream if you don't want to mix your Streams and Writers

How to convert a String[] array to InputStream in Java

You can construct a merged String with some separator and then to byte[] and then to ByteArrayInputStream.

Here's a way to convert a String to InputStream in Java.

How to convert a String to an InputStream in Kotlin?

Kotlin has an extension for String to convert directly.

val inputStream: InputStream = myString.byteInputStream()

The argument on byteInputStream is defaulted to charset: Charset = Charsets.UTF_8.

You can look at the extension by writing it and then cmd+click on it or in the package kotlin.io file IOStream.kt

Relying on the Java version is not wrong, but rather using a more kotlin idiomatic way when possible

How do I turn a String into a InputStreamReader in java?

ByteArrayInputStream also does the trick:

InputStream is = new ByteArrayInputStream( myString.getBytes( charset ) );

Then convert to reader:

InputStreamReader reader = new InputStreamReader(is);

How does one create an InputStream from a String?

Here you go:

InputStream is = new ByteArrayInputStream( myString.getBytes() );

Update For multi-byte support use (thanks to Aaron Waibel's comment):

InputStream is = new ByteArrayInputStream(Charset.forName("UTF-16").encode(myString).array());

Please see ByteArrayInputStream manual.

It is safe to use a charset argument in String#getBytes(charset) method above.

After JDK 7+ you can use

java.nio.charset.StandardCharsets.UTF_16

instead of hardcoded encoding string:

InputStream is = new ByteArrayInputStream(StandardCharsets.UTF_16.encode(myString).array());

How can I convert a String into a DataInputStream type in Java?

This might help

import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.InputStream;
import java.nio.charset.Charset;

public class MyApp {

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

        InputStream is = new ByteArrayInputStream("hi I am test".getBytes(Charset.forName("UTF-8")));

        DataInputStream dataIn = new DataInputStream(is);
        while (dataIn.available() > 0) {
            String k = dataIn.readLine();
            System.out.print(k + " ");
        }
    }

}

Java: accessing a List of Strings as an InputStream

You can concatenate all the lines together to create a String then convert it to a byte array using String#getBytes and pass it into ByteArrayInputStream. However this is not the most efficient way of doing it.

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