Add android-example.

Cargo.toml

@@ -1,6 +1,7 @@
 [workspace]
 members = [
     "android-build-tools",
+    "android-examples",
     "android-glue",
     "android-ndk-sys",
     "android-ndk",

android-examples/Cargo.toml

@@ -0,0 +1,12 @@
+[package]
+name = "android-examples"
+version = "0.1.0"
+authors = ["David Craven <[email protected]>"]
+edition = "2018"
+
+[target.'cfg(target_os = "android")'.dependencies]
+android-glue = { path = "../android-glue" }
+
+[[example]]
+name = "hello_world"
+crate-type = ["cdylib"]

android-examples/examples/hello_world.rs

@@ -0,0 +1,19 @@
+#[cfg(target_os = "android")]
+#[no_mangle]
+pub unsafe extern "C" fn ANativeActivity_onCreate(
+    activity: *mut std::os::raw::c_void,
+    saved_state: *mut std::os::raw::c_void,
+    saved_state_size: usize,
+) {
+    std::env::set_var("RUST_BACKTRACE", "1");
+    android_glue::init(
+        activity as _,
+        saved_state as _,
+        saved_state_size as _,
+        app_main,
+    );
+}
+
+pub fn app_main() {
+    println!("hello world");
+}

android-examples/src/lib.rs

@@ -0,0 +1 @@
+