Utils for I/O operations

IoUtils.java

import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import okhttp3.internal.io.FileSystem;
import okio.BufferedSource;
import okio.Okio;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;

/**
 * Utils for I/O operations.
 */
public class IoUtils {
  /**
   * Reads file and returns a String.
   *
   * @param file the file to read
   * @return the string with file content or null
   */
  @Nullable
  public static String tryReadFile(@NonNull final File file) {
    try (final BufferedSource source = Okio.buffer(FileSystem.SYSTEM.source(file))) {
      return source.readUtf8();
    } catch (final IOException exception) {
      //ignored exception
      return null;
    }
  }

  /**
   * Reads InputStream and returns a String. It will close stream after usage.
   *
   * @param stream the stream to read
   * @return the string with file content or null
   */
  @Nullable
  public static String tryReadFile(@NonNull final InputStream stream) {
    try (final BufferedSource source = Okio.buffer(Okio.source(stream))) {
      return source.readUtf8();
    } catch (final IOException exception) {
      //ignored exception
      return null;
    }
  }

  /**
   * Reads file and returns a String.
   *
   * @param file the file to read
   * @return the string content
   */
  @NonNull
  public static String readFile(@NonNull final File file) throws IOException {
    try (final BufferedSource source = Okio.buffer(FileSystem.SYSTEM.source(file))) {
      return source.readUtf8();
    }
  }

  /**
   * Reads InputStream and returns a String. It will close stream after usage.
   *
   * @param stream the stream to read
   * @return the string content
   */
  @NonNull
  public static String readFile(@NonNull final InputStream stream) throws IOException {
    try (final BufferedSource source = Okio.buffer(Okio.source(stream))) {
      return source.readUtf8();
    }
  }
}

Thank you very much it is best code reduce more much time during read file contain.

It's only supported by API 19 and up, because it uses try-with-resources mechanism

I edited it a little bit to support android version below API 19 https://gist.github.com/hendrawd/a2a975e21799294801d2d8d9ba5eed1f