Manipulating arrays in JNI

JNI exposes strings, classes, instance objects, and arrays as reference types. This recipe will discuss arrays in JNI.

Getting ready

You should make sure you've read the following recipes before going through this recipe:

• Managing references in JNI

• Manipulating classes in JNI

How to do it…

In this section, we will create a sample Android project that demonstrates how to manipulate arrays in JNI.

1. Create a project named ArrayManipulation. Set the package name as cookbook.chapter2. Create an activity named ArrayManipulationActivity. Under the project, create a folder named jni. Refer to the Loading native libraries and registering native methods recipe of this chapter for more detailed instructions.

2. Create a file named arraytest.c under the jni folder, then implement the GetArrayLengthDemo, NewObjectArrayDemo, NewIntArrayDemo, GetSetObjectArrayDemo, GetReleaseIntArrayDemo, GetSetIntArrayRegionDemo, and GetReleasePrimitiveArrayCriticalDemo native methods.

3. Modify ArrayManipulationActivity...