Add VAD demo for Java API (#928)

sherpa-onnx/jni/wave-writer.cc

@@ -0,0 +1,23 @@
+// sherpa-onnx/jni/wave-writer.cc
+//
+// Copyright (c)  2024  Xiaomi Corporation
+#include "sherpa-onnx/csrc/wave-writer.h"
+
+#include "sherpa-onnx/jni/common.h"
+
+SHERPA_ONNX_EXTERN_C
+JNIEXPORT bool JNICALL Java_com_k2fsa_sherpa_onnx_WaveWriter_writeWaveToFile(
+    JNIEnv *env, jclass /*obj*/, jstring filename, jfloatArray samples,
+    jint sample_rate) {
+  jfloat *p = env->GetFloatArrayElements(samples, nullptr);
+  jsize n = env->GetArrayLength(samples);
+
+  const char *p_filename = env->GetStringUTFChars(filename, nullptr);
+
+  bool ok = sherpa_onnx::WriteWave(p_filename, sample_rate, p, n);
+
+  env->ReleaseFloatArrayElements(samples, p, JNI_ABORT);
+  env->ReleaseStringUTFChars(filename, p_filename);
+
+  return ok;
+}