'Files.readString()' or 'Files.writeString()' can be used

Reports method calls that read or write a String as bytes using java.nio.file.Files. Such calls can be replaced with a call to a Files.readString() or Files.writeString() method introduced in Java 11.

Example:

  String s = "example";
  Files.write(Paths.get("out.txt"), s.getBytes(StandardCharsets.UTF_8), StandardOpenOption.WRITE);
  s = new String(Files.readAllBytes(Paths.get("in.txt")), StandardCharsets.ISO_8859_1);

After the quick fix is applied:

  String s = "example";
  Files.writeString(Paths.get("out.txt"), s, StandardOpenOption.WRITE);
  s = Files.readString(Paths.get("in.txt"), StandardCharsets.ISO_8859_1);

Note that the readString() behavior differs from the new String(bytes, charset) behavior when it comes to handling of invalid (unmappable) characters. The readString() method throws an exception in such cases, while the new String(bytes, charset) method silently replaces invalid characters with the replacement character. If silent replacement is desired, it would be better to suppress the inspection warning.

Locating this inspection

By ID

Can be used to locate inspection in e.g. Qodana configuration files, where you can quickly enable or disable it, or adjust its settings.

ReadWriteStringCanBeUsed

Via Settings dialog

Path to the inspection settings via IntelliJ Platform IDE Settings dialog, when you need to adjust inspection settings directly from your IDE.

Inspection ID: ReadWriteStringCanBeUsed

New in 2018.3

Suppressing Inspection

You can suppress this inspection by placing the following comment marker before the code fragment where you no longer want messages from this inspection to appear:

//noinspection ReadWriteStringCanBeUsed

More detailed instructions as well as other ways and options that you have can be found in the product documentation:

IntelliJ IDEA 2025.3

Inspection Details
By default bundled with:	IntelliJ IDEA 2025.3, Qodana for JVM 2025.3,

Last modified: 03 December 2025