| <!DOCTYPE html><html><head><title>R: Call Java Methods</title> |
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| <table style="width: 100%;"><tr><td>sparkR.callJMethod {SparkR}</td><td style="text-align: right;">R Documentation</td></tr></table> |
| |
| <h2>Call Java Methods</h2> |
| |
| <h3>Description</h3> |
| |
| <p>Call a Java method in the JVM running the Spark driver. The return |
| values are automatically converted to R objects for simple objects. Other |
| values are returned as "jobj" which are references to objects on JVM. |
| </p> |
| |
| |
| <h3>Usage</h3> |
| |
| <pre><code class='language-R'>sparkR.callJMethod(x, methodName, ...) |
| </code></pre> |
| |
| |
| <h3>Arguments</h3> |
| |
| <table> |
| <tr style="vertical-align: top;"><td><code>x</code></td> |
| <td> |
| <p>object to invoke the method on. Should be a "jobj" created by newJObject.</p> |
| </td></tr> |
| <tr style="vertical-align: top;"><td><code>methodName</code></td> |
| <td> |
| <p>method name to call.</p> |
| </td></tr> |
| <tr style="vertical-align: top;"><td><code>...</code></td> |
| <td> |
| <p>parameters to pass to the Java method.</p> |
| </td></tr> |
| </table> |
| |
| |
| <h3>Details</h3> |
| |
| <p>This is a low level function to access the JVM directly and should only be used |
| for advanced use cases. The arguments and return values that are primitive R |
| types (like integer, numeric, character, lists) are automatically translated to/from |
| Java types (like Integer, Double, String, Array). A full list can be found in |
| serialize.R and deserialize.R in the Apache Spark code base. |
| </p> |
| |
| |
| <h3>Value</h3> |
| |
| <p>the return value of the Java method. Either returned as a R object |
| if it can be deserialized or returned as a "jobj". See details section for more. |
| </p> |
| |
| |
| <h3>Note</h3> |
| |
| <p>sparkR.callJMethod since 2.0.1 |
| </p> |
| |
| |
| <h3>See Also</h3> |
| |
| <p><a href="../../SparkR/help/sparkR.callJStatic.html">sparkR.callJStatic</a>, <a href="../../SparkR/help/sparkR.newJObject.html">sparkR.newJObject</a> |
| </p> |
| |
| |
| <h3>Examples</h3> |
| |
| <pre><code class="r">## Not run: |
| ##D sparkR.session() # Need to have a Spark JVM running before calling newJObject |
| ##D # Create a Java ArrayList and populate it |
| ##D jarray <- sparkR.newJObject("java.util.ArrayList") |
| ##D sparkR.callJMethod(jarray, "add", 42L) |
| ##D sparkR.callJMethod(jarray, "get", 0L) # Will print 42 |
| ## End(Not run) |
| </code></pre> |
| |
| |
| <hr /><div style="text-align: center;">[Package <em>SparkR</em> version 3.2.2 <a href="00Index.html">Index</a>]</div> |
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