docs.sheetjs.com/docz/docs/03-demos/12-engines/04_nashorn.md

---
title: Java + Nashorn
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---

import Tabs from '@theme/Tabs';
import TabItem from '@theme/TabItem';

Nashorn is a JavaScript engine for Java.  It shipped with Java distributions
starting with Java 8 and was eventually removed in Java 15. The project was
spun off and a compatible standalone release is available for Java 15+.

The [Standalone scripts](/docs/getting-started/installation/standalone) can be
parsed and evaluated in a Nashorn context.

## Integration Details

_Initialize Nashorn_

`global` must be created from a Nashorn engine:

```java
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import java.nio.file.Files;
import java.nio.file.Paths;
import java.util.Scanner;

/* initialize nashorn engine */
ScriptEngine engine = (new ScriptEngineManager()).getEngineByName("javascript");

/* create global */
engine.eval("var global = (function(){ return this; }).call(null);");
```

_Load SheetJS Scripts_

The main library can be loaded by reading the script from the file system and
evaluating in the Nashorn context:

```java
engine.eval(new Scanner(
  SheetJS.class.getResourceAsStream("/xlsx.full.min.js")
).useDelimiter("\\Z").next());
```

To confirm the library is loaded, `XLSX.version` can be printed using the
Nashorn `print` built-in:

```java
engine.eval("print('SheetJS Version ' + XLSX.version);");
```

### Reading Files

Nashorn does not properly project `byte[]` into a JS array or `Int8Array`. The
recommended workaround is to copy the data in the JS context using the JS code:

```js
function b2a(b) {
  var out = typeof Uint8Array == 'function' ? new Uint8Array(b.length) : new Array(b.length);
  /* `b` is similar to Int8Array (values in the range -128 .. 127 ) */
  for(var i = 0; i < out.length; i++) out[i] = (b[i] + 256) & 0xFF;
  return out;
}
```

This function should be embedded in the Java code:

```java
/* read spreadsheet bytes */
engine.put("bytes", Files.readAllBytes(Paths.get(args[0])));

/* convert signed byte array to JS Uint8Array or unsigned byte array */
engine.eval(
  "function b2a(b) {" +
    "var out = typeof Uint8Array == 'function' ? new Uint8Array(b.length) : new Array(b.length);" +
    "for(var i = 0; i < out.length; i++) out[i] = (b[i] + 256) & 0xFF;" +
    "return out;" +
  "}" +
  "var u8a = b2a(bytes)"
);

/* parse workbook */
engine.eval("var wb = XLSX.read(u8a, {type: 'array'})");
```

## Complete Example

:::note

This demo was last tested on 2023 March 27 using:

- OpenJDK 19.0.1  + Nashorn 15.4 standalone
- OpenJDK 11.0.18 + Official Nashorn

:::

<Tabs groupId="java">
  <TabItem value="stdlib" label="Java 8 - 14">

Nashorn is available without additional dependencies

  </TabItem>
  <TabItem value="standalone" label="Java 15+">

0) Download Nashorn and its dependencies:

```bash
curl -LO "https://search.maven.org/remotecontent?filepath=org/openjdk/nashorn/nashorn-core/15.4/nashorn-core-15.4.jar"
curl -LO "https://search.maven.org/remotecontent?filepath=org/ow2/asm/asm/9.5/asm-9.5.jar"
curl -LO "https://search.maven.org/remotecontent?filepath=org/ow2/asm/asm-tree/9.5/asm-tree-9.5.jar"
curl -LO "https://search.maven.org/remotecontent?filepath=org/ow2/asm/asm-commons/9.5/asm-commons-9.5.jar"
curl -LO "https://search.maven.org/remotecontent?filepath=org/ow2/asm/asm-analysis/9.5/asm-analysis-9.5.jar"
curl -LO "https://search.maven.org/remotecontent?filepath=org/ow2/asm/asm-util/9.5/asm-util-9.5.jar"
```

  </TabItem>
</Tabs>

1) Download the standalone script, shim script, and the test file:

<ul>
<li><a href={`https://cdn.sheetjs.com/xlsx-latest/package/dist/xlsx.full.min.js`}>xlsx.full.min.js</a></li>
<li><a href={`https://cdn.sheetjs.com/xlsx-latest/package/dist/shim.min.js`}>shim.min.js</a></li>
<li><a href="https://sheetjs.com/pres.xlsx">pres.xlsx</a></li>
</ul>

```bash
curl -LO https://cdn.sheetjs.com/xlsx-latest/package/dist/xlsx.full.min.js
curl -LO https://cdn.sheetjs.com/xlsx-latest/package/dist/shim.min.js
curl -LO https://sheetjs.com/pres.xlsx
```

2) Download [`SheetJSNashorn.java`](pathname:///nashorn/SheetJSNashorn.java):

```bash
curl -LO https://docs.sheetjs.com/nashorn/SheetJSNashorn.java
```

3) Build the sample class:

```bash
javac SheetJSNashorn.java
```

This program tries to parse the file specified by the first argument

4) Run the command directly:

<Tabs groupId="java">
  <TabItem value="stdlib" label="Java 8 - 14">

```bash
java SheetJSNashorn pres.xlsx
```

  </TabItem>
  <TabItem value="standalone" label="Java 15+">

```bash
java -cp .:asm-9.5.jar:asm-tree-9.5.jar:asm-commons-9.5.jar:asm-analysis-9.5.jar:asm-util-9.5.jar:nashorn-core-15.4.jar SheetJSNashorn pres.xlsx
```

  </TabItem>
</Tabs>


5) Assemble a Java Archive:

```bash
jar -cf SheetJSNashorn.jar SheetJSNashorn.class xlsx.full.min.js shim.min.js
```

6) Verify the Java Archive.

Create new directory and copy the archives and test file:

```bash
mkdir -p sheethorn
cp *.jar pres.xlsx sheethorn
cd sheethorn
```

Invoke the command in the archive:

<Tabs groupId="java">
  <TabItem value="stdlib" label="Java 8 - 14">

```bash
java -cp .:SheetJSNashorn.jar SheetJSNashorn pres.xlsx
```

  </TabItem>
  <TabItem value="standalone" label="Java 15+">

```bash
java -cp .:asm-9.5.jar:asm-tree-9.5.jar:asm-commons-9.5.jar:asm-analysis-9.5.jar:asm-util-9.5.jar:nashorn-core-15.4.jar:SheetJSNashorn.jar SheetJSNashorn pres.xlsx
```

  </TabItem>
</Tabs>