Java2OP.exe, the Native Bridge File Generator for Android

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Java2OP.exe ("Java To Object Pascal") is a command-line tool that you can use to generate Delphi native bridge files from Java libraries (JAR or class files). You can use the generated files to provide your Delphi applications access to those Java libraries on Android. See Using a Custom Set of Java Libraries In Your RAD Studio Android Apps.

Java2OP.exe is installed by RAD Studio as part of the Android platform target support. If the Android platform target is installed, it can be found in the bin\converters\java2op folder within the RAD Studio installation. So, for example, in RAD Studio Alexandria 11.0, the full path is:

C:\Program Files (x86)\Embarcadero\Studio\22.0\bin\converters\java2op\Java2OP.exe


To use this tool, simply call the tool with any combination of options that you like:

Java2OP.exe [options]

You must specify at least one input option that indicates what content you want to include in the output Delphi native bridge file.

Your output native bridge file does not include members that are part of the built-in RAD Studio Java libraries for Android unless you explicitly specify those members using the -classes parameter. If any of the classes that you specified depends on members from the built-in RAD Studio Java libraries for Android, the resulting native bridge file does not redeclare those members; instead, it includes the RAD Studio units that already declare those members.

Input Options

Option Description


Space-separated list of names of classes or packages to export.

-classes lets you define a specific subset of the specified Java sources (-jar or -src options) or the Android API.


Space-separated list of input Java compiled libraries (.jar files). All API members of the specified files are parsed and declared on the resulting native bridge file.


Space-separated list of input folders containing Java source files (.java files). All API members of the files in the specified folders are parsed and declared on the resulting native bridge file.

Output Options

Option Description


File name of the output unit.

Default: Android.JNI.Interfaces


Exporting some classes and packages from the Android API:

Java2OP.exe -classes android.location.*

Exporting all classes from mylib.jar:

Java2OP.exe -jar mylib.jar

Exporting a single class from mylib.jar:

Java2OP.exe -jar mylib.jar -classes com.mypackage.ClassName

Exporting all the classes from a folder of Java sources specifying the file name of the output Delphi unit:

Java2OP.exe -src myproject/src -unit Android.JNI.UnitName


Missing JDK

“Missing JDK. Please install JDK 1.7+ or make sure that it is on your PATH”

To use Java2OP.exe, you must install Java and the JDK 1.7+.

If you have installed the JDK and you still get this error, the reason is that the JDK binary folder has not been found in any of the paths in your PATH environment variable. Add the bin folder of your JDK installation directory to your PATH.

For example, from the command line:

SET PATH=%PATH%;C:\Program Files\Java\jdk1.7.0_25\bin

EListError error

“EListError error raised, with message : Duplicates not allowed”

You specified a source or JAR file more than once.

Since Java2OP.exe includes the Android API as input by default, you also get this error if you include the Android API JAR file manually using the -jar option. For example, this does not work:

Java2OP.exe -jar android.jar

If you want to extract members from the Android API, simply specify a -classes option. For example:

Java2OP.exe -classes android.animation.*

See Also