Add a function to construct std::string from native_jstring

ttnghia · Feb 11, 2022 · 00d7d8b · 00d7d8b
1 parent 1b4cd51
commit 00d7d8b
Showing 1 changed file with 9 additions and 3 deletions.
diff --git a/java/src/main/native/include/jni_utils.hpp b/java/src/main/native/include/jni_utils.hpp
@@ -17,6 +17,7 @@
 
 #include <algorithm>
 #include <memory>
+#include <string>
 #include <vector>
 
 #include <jni.h>
@@ -524,7 +525,7 @@ class native_jstring {
   void init_cstr() const {
     if (orig != NULL && cstr == NULL) {
       cstr_length = env->GetStringUTFLength(orig);
-      cstr = env->GetStringUTFChars(orig, 0);
+      cstr = env->GetStringUTFChars(orig, 0); // not guarantee to have null terminated.
       check_java_exception(env);
     }
   }
@@ -555,6 +556,7 @@ class native_jstring {
 
   bool is_null() const noexcept { return orig == NULL; }
 
+  // Note that the char* return by this function is not guaranteed to be null-terminated.
   const char *get() const {
     init_cstr();
     return cstr;
@@ -565,6 +567,12 @@ class native_jstring {
     return cstr_length;
   }
 
+  // Note that the char* return by `get()` is not guaranteed to be null-terminated.
+  // Thus, constructing an std::string should be performed with a string size supplied.
+  std::string get_cpp_str() const { return std::string(get(), size_bytes()); }
+
+  jstring get_jstring() const { return orig; }
+
   bool is_empty() const {
     if (cstr != NULL) {
       return cstr_length <= 0;
@@ -576,8 +584,6 @@ class native_jstring {
     return true;
   }
 
-  const jstring get_jstring() const { return orig; }
-
   ~native_jstring() {
     if (orig != NULL && cstr != NULL) {
       env->ReleaseStringUTFChars(orig, cstr);