java.io Recipes

These recipes use Okio with java.io.File instead of Okio's own Path and FileSystem types.

Read a text file line-by-line (Java/Kotlin)

This is similar to the other line-by-line example, but it uses java.io.File instead of okio.Path and okio.FileSystem.

=== “Java”

```java
public void readLines(File file) throws IOException {
  try (Source fileSource = Okio.source(file);
       BufferedSource bufferedFileSource = Okio.buffer(fileSource)) {

    while (true) {
      String line = bufferedFileSource.readUtf8Line();
      if (line == null) break;

      if (line.contains("square")) {
        System.out.println(line);
      }
    }

  }
}
```

=== “Kotlin”

Note that static `Okio` methods become extension functions (`Okio.source(file)` =>
`file.source()`).

```kotlin
@Throws(IOException::class)
fun readLines(file: File) {
  file.source().use { fileSource ->
    fileSource.buffer().use { bufferedFileSource ->
      while (true) {
        val line = bufferedFileSource.readUtf8Line() ?: break
        if ("square" in line) {
          println(line)
        }
      }
    }
  }
}
```

Write a text file (Java/Kotlin)

This is similar to the other write example, but it uses java.io.File instead of okio.Path and okio.FileSystem.

=== “Java”

```java
public void writeEnv(File file) throws IOException {
  try (Sink fileSink = Okio.sink(file);
       BufferedSink bufferedSink = Okio.buffer(fileSink)) {

    for (Map.Entry<String, String> entry : System.getenv().entrySet()) {
      bufferedSink.writeUtf8(entry.getKey());
      bufferedSink.writeUtf8("=");
      bufferedSink.writeUtf8(entry.getValue());
      bufferedSink.writeUtf8("\n");
    }

  }
}
```

=== “Kotlin”

```kotlin
@Throws(IOException::class)
fun writeEnv(file: File) {
  file.sink().buffer().use { sink ->
    for ((key, value) in System.getenv()) {
      sink.writeUtf8(key)
      sink.writeUtf8("=")
      sink.writeUtf8(value)
      sink.writeUtf8("\n")
    }
  }
}
```