Solution 1:

This is an example of how to use the Base64 class to encode and decode a simple String value.

// String to be encoded with Base64
String text = "Test";
// Sending side
byte[] data = null;
try {
    data = text.getBytes("UTF-8");
} catch (UnsupportedEncodingException e1) {
    e1.printStackTrace();
}
String base64 = Base64.encodeToString(data, Base64.DEFAULT);

// Receiving side
byte[] data1 = Base64.decode(base64, Base64.DEFAULT);
String text1 = null;
try {
    text1 = new String(data1, "UTF-8");
} catch (UnsupportedEncodingException e) {
    e.printStackTrace();
}

This excerpt can be included in an Android activity.

Solution 2:

See android.util.Base64

It seems that this was added in API version 8 or android 2.2 so it will not be available on the older platforms.

But the source of it is at android/util/Base64.java so if needed one could just copy it unchanged for older versions.

Solution 3:

Here is a simple method I was going to use until I realized that this is only supported in Android API 8+:

// Has line break
public String getBase64(String input) {
    return Base64.encodeToString(input.getBytes(), Base64.DEFAULT);
}

// No line break
public String getBase64(String input) {
    return Base64.encodeToString(input.getBytes(), Base64.NO_WRAP);
}