First Steps With QtJambi

Add qtjambi.jar to the classpath of your Java project containing the most essential Qt Core, Gui and Widgets modules. If you use Maven to build your application simply add following dependency to your project:

<dependency>
  <groupId>io.qtjambi</groupId>
  <artifactId>qtjambi</artifactId>
  <version>$VERSION</version>
</dependency>

(exchange $VERSION either by 6.8.3, 6.9.0 or any other published version).

Otherwise, download QtJambi JAR file from Maven Central Repository. Find the list of all available QtJambi modules.

Example Program

Create a file Test.java containing the following code

import io.qt.widgets.*;
public class Test {
    public static void main(String[] args) {
        QApplication.initialize(args);
        QMessageBox.information(null, "QtJambi", "Hello World!");
        QApplication.shutdown();
    }
}

Compile the file:

javac -cp qtjambi-6.8.3.jar Test.java

Executing Example

For execution you need the platform dependent binaries of QtJambi. For instance, if you are working on Windows download the windows-x64 binaries (qtjambi-native-windows-x64-VERSION.jar) from Maven Central Repository and add it to java class path.

Additionally, you need Qt. Use the Qt installer to install Qt on your system. Make sure you are using the same Qt version and QtJambi version (the first and second version digit needs to be the same, e.g. 6.8 or 6.9).

On Windows install Qt for MSVC (msvc2022_64), as the Maven-published QtJambi binaries are not compatible with Qt builds based on Mingw pr LLVM-Mingw.

On Linux, you can alternatively use Qt system libraries (correct version provided). The required DLLs are to be found in the bin folder on Windows and lib folder on Linux and macOS, respectively.

When running a QtJambi application you have to make the locations of Qt and QtJambi libraries known to Java. Therefore, use the PATH environment (LD_LIBRARY_PATH on Linux, DYLD_FRAMEWORK_PATH on macOS) or the Java runtime property java.library.path.

The example program can be executed this way on Windows:

java -cp qtjambi-6.8.3.jar;qtjambi-native-windows-x64-6.8.3.jar;. -Djava.library.path=C:\Qt\6.8.3\msvc2022_64\bin Test

On Linux it looks this way:

java -cp qtjambi-6.8.3.jar:qtjambi-native-linux-x64-6.8.3.jar:. -Djava.library.path=<path to>/Qt/6.8.3/gcc_64/lib Test

On macOS you additionally need to use the start parameter -XstartOnFirstThread:

java -cp qtjambi-6.8.3.jar:qtjambi-native-macos-6.8.3.jar:. -Djava.library.path=<path to>/Qt/6.8.3/macos/lib -XstartOnFirstThread Test

On Linux, if your distribution provides Qt (of correct version) as system library you don't need to specify library path at all. However, since Maven-published binaries for Linux have been built with Qt from installer they might be incompatible to your system-specific Qt. In this case it is recommended to build QtJambi on your Linux system by using the installed qmake or install Qt by using Qt installer.

If the example fails with a UnsatisfiedLinkError QtJambi libraries and Qt libraries seem to be incompatible. Read here about library requirements and compatibility.

Native Components

QtJambi automatically detects the required native component jars if they are located next to their Java counterparts or in a subfolder native. You can simply skip adding qtjambi-native-OS-VERSION.jar to your classpath (-cp).

If you intend to use automatic module loading (java -p <dir>) you strictly need to place native components in native subfolder next to qtjambi-6.8.3.jar.

Native bundles are extracted every time at program startup. By default, this is a process specific temporal directory purged after program shutdown. Alternatively, you can use Java system property io.qt.deploymentdir to let libraries to be exctacted and persist in user application data path or common directory (see Library Management).

First Steps With QtJambi

Example Program

Executing Example

Native Components

Further Reading