How to call Qt windows in Java?

To use Qt forms in Java, you need to use JNI (Java Native Interface). You first need to create a dynamic link library (.dll file) for the Qt form, and then call the functions in that library using JNI in the Java code.

Here is a simple example to demonstrate how to call Qt forms in Java.

1. Firstly, create a Qt project and write a window class, for example MyWindow:

#include <QMainWindow>

class MyWindow : public QMainWindow {
    Q_OBJECT

public:
    MyWindow(QWidget *parent = nullptr);
    ~MyWindow();
};

1. Generate dynamic link library (.dll file) in Qt project.

Add the following code to the .pro file:

TARGET = mywindow
TEMPLATE = lib

HEADERS += mywindow.h
SOURCES += mywindow.cpp

1. Generate a dynamic link library in a Qt project and copy the resulting .dll file to the directory of the Java project.
2. Using JNI to call Qt forms in a Java project.

public class QtWindowTest {
    static {
        System.loadLibrary("MyWindow"); // 加载Qt窗体的动态链接库
    }

    private native void showQtWindow();

    public static void main(String[] args) {
        QtWindowTest test = new QtWindowTest();
        test.showQtWindow();
    }
}

1. Compile the Java project and place the dynamic link library (.dll file) of the Qt form in the directory of the Java project.
2. Running the Java project will allow you to see the effect of calling the Qt window.

Please note that the above examples are for reference only, and adjustments may be needed based on specific circumstances in actual projects. Also, when using JNI to call Qt forms, it is important to consider issues such as thread safety and memory management.