class CatchThrow {private native void doit()throws IllegalArgumentException;private void callback() throws NullPointerException {throw new NullPointerException("CatchThrow.callback");}public static void main(String args[]) {CatchThrow c = new CatchThrow();try {c.doit();} catch (Exception e) {System.out.println("In Java:\n\t" + e);}}static {System.loadLibrary("CatchThrow");}
}

JNIEXPORT void JNICALL
Java_CatchThrow_doit(JNIEnv *env, jobject obj)
{jthrowable exc;jclass cls = (*env)->GetObjectClass(env, obj);jmethodID mid = (*env)->GetMethodID(env, cls, "callback", "()V");if (mid == NULL) {return;}(*env)->CallVoidMethod(env, obj, mid);exc = (*env)->ExceptionOccurred(env);if (exc) {/* We don't do much with the exception, except thatwe print a debug message for it, clear it, andthrow a new exception. */jclass newExcCls;(*env)->ExceptionDescribe(env);(*env)->ExceptionClear(env);newExcCls = (*env)->FindClass(env,"java/lang/IllegalArgumentException");if (newExcCls == NULL) {/* Unable to find the exception class, give up. */return;}(*env)->ThrowNew(env, newExcCls, "thrown from C code");}
}

java.lang.NullPointerException:at CatchThrow.callback(CatchThrow.java)at CatchThrow.doit(Native Method)at CatchThrow.main(CatchThrow.java)
In Java:java.lang.IllegalArgumentException: thrown from C code

/* a class in the Java programming language */
public class Window {long handle;int length;int width;static native void initIDs();static {initIDs();}
}/* C code that implements Window.initIDs */
jfieldID FID_Window_handle;
jfieldID FID_Window_length;
jfieldID FID_Window_width;
JNIEXPORT void JNICALL
Java_Window_initIDs(JNIEnv *env, jclass classWindow)
{FID_Window_handle =(*env)->GetFieldID(env, classWindow, "handle", "J");if (FID_Window_handle == NULL) {  /* important check. */return; /* error occurred. */}FID_Window_length =(*env)->GetFieldID(env, classWindow, "length", "I");if (FID_Window_length == NULL) {  /* important check. */return; /* error occurred. */}FID_Window_width =(*env)->GetFieldID(env, classWindow, "width", "I");/* no checks necessary; we are about to return anyway */
}

public class Fraction {// details such as constructors omittedint over, under;public int floor() {return Math.floor((double)over/under);}
}/* Native code that calls Fraction.floor. Assume method IDMID_Fraction_floor has been initialized elsewhere. */
void f(JNIEnv *env, jobject fraction)
{jint floor = (*env)->CallIntMethod(env, fraction,MID_Fraction_floor);/* important: check if an exception was raised */if ((*env)->ExceptionCheck(env)) {return;}... /* use floor */
}

JNIEXPORT void JNICALL
Java_pkg_Cls_f(JNIEnv *env, jclass cls, jstring jstr)
{const jchar *cstr = (*env)->GetStringChars(env, jstr);if (c_str == NULL) {return;}...if (...) { /* exception occurred */(*env)->ReleaseStringChars(env, jstr, cstr);return;}.../* normal return */(*env)->ReleaseStringChars(env, jstr, cstr);
}