When C# calls a Java package, it throws an error stating: “The type initializer for java.lang.StdIO”

To call a Java package in C#, you need to use Java interoperability features. Common methods include using Java Native Interface (JNI) or Java Native Access (JNA). Here is an example of using JNI:

using System;
using System.Runtime.InteropServices;

public class Program
{
    // 加载Java库
    [DllImport("jvm.dll")]
    private static extern int JNI_CreateJavaVM(out IntPtr jvm, out IntPtr env, IntPtr vmArgs);

    static void Main(string[] args)
    {
        // 创建Java虚拟机
        IntPtr jvm;
        IntPtr env;
        int result = JNI_CreateJavaVM(out jvm, out env, IntPtr.Zero);
        if (result < 0)
        {
            Console.WriteLine("无法创建Java虚拟机");
            return;
        }

        try
        {
            // 调用Java代码
            JNIEnv jniEnv = new JNIEnv(env);
            JClass stdioClass = jniEnv.FindClass("java/lang/StdIO");
            if (stdioClass == null)
            {
                Console.WriteLine("无法找到java.lang.StdIO类");
                return;
            }

            // 调用StdIO的方法
            JMethodID printMethod = jniEnv.GetStaticMethodID(stdioClass, "print", "(Ljava/lang/String;)V");
            if (printMethod == null)
            {
                Console.WriteLine("无法找到print方法");
                return;
            }

            jstring message = jniEnv.NewStringUTF("Hello from C#!");
            jniEnv.CallStaticVoidMethod(stdioClass, printMethod, message);
        }
        finally
        {
            // 销毁Java虚拟机
            jniEnv.DestroyJavaVM();
        }
    }
}

// 辅助类来处理JNI调用
public class JNIEnv
{
    private IntPtr env;

    public JNIEnv(IntPtr env)
    {
        this.env = env;
    }

    public JClass FindClass(string className)
    {
        IntPtr classRef = CallObjectMethod("FindClass", new JString(className).Handle);
        return new JClass(classRef, this);
    }

    public JMethodID GetStaticMethodID(JClass classRef, string methodName, string signature)
    {
        return new JMethodID(CallObjectMethod("GetStaticMethodID", classRef.Handle, new JString(methodName).Handle, new JString(signature).Handle), this);
    }

    public void CallStaticVoidMethod(JClass classRef, JMethodID methodId, jvalue[] args)
    {
        CallVoidMethod("CallStaticVoidMethod", classRef.Handle, methodId.Handle, args);
    }

    public void DestroyJavaVM()
    {
        CallVoidMethod("DestroyJavaVM");
    }

    private IntPtr CallObjectMethod(string methodName, params IntPtr[] args)
    {
        IntPtr methodId = GetMethodID(methodName, args);
        return CallObjectMethod(methodId, args);
    }

    private IntPtr CallObjectMethod(IntPtr methodId, params IntPtr[] args)
    {
        return JNI.CallObjectMethod(env, methodId, args);
    }

    private void CallVoidMethod(string methodName, params IntPtr[] args)
    {
        IntPtr methodId = GetMethodID(methodName, args);
        CallVoidMethod(methodId, args);
    }

    private void CallVoidMethod(IntPtr methodId, params IntPtr[] args)
    {
        JNI.CallVoidMethod(env, methodId, args);
    }

    private IntPtr GetMethodID(string methodName, IntPtr[] args)
    {
        return CallObjectMethod("GetMethodID", args[0], new JString(methodName).Handle, args[1]);
    }
}

// Java字符串类的封装
public class JString
{
    public IntPtr Handle { get; private set; }

    public JString(string value)
    {
        Handle = JNI.NewStringUTF(value);
    }

    ~JString()
    {
        JNI.DeleteLocalRef(Handle);
    }
}

// Java类的封装
public class JClass
{
    public IntPtr Handle { get; private set; }
    private JNIEnv env;

    public JClass(IntPtr handle, JNIEnv env)
    {
        Handle = handle;
        this.env = env;
    }

    public JMethodID GetStaticMethodID(string methodName, string signature)
    {
        return env.GetStaticMethodID(this, methodName, signature);
    }
}

// Java方法的封装
public class JMethodID
{
    public IntPtr Handle { get; private set; }
    private JNIEnv env;

    public JMethodID(IntPtr handle, JNIEnv env)
    {
        Handle = handle;
        this.env = env;
    }

    public void CallStaticVoidMethod(params jvalue[] args)
    {
        env.CallStaticVoidMethod(this, args);
    }
}

//