Update sample project

Author: koji-1009

sdk-example-kt/src/main/java/jp/studyplus/android/sdk_example_kt/MainActivity.kt

@@ -38,6 +38,13 @@ class MainActivity : AppCompatActivity() {
             }
         }
 
+        findViewById<View>(R.id.cancel_auth)?.apply {
+            setOnClickListener {
+                Studyplus.instance.cancelAuth(this@MainActivity)
+                updateAuthText()
+            }
+        }
+
         findViewById<View>(R.id.post_study_record)?.apply {
             setOnClickListener {
                 val record = StudyRecord(
@@ -64,7 +71,10 @@ class MainActivity : AppCompatActivity() {
 
     override fun onResume() {
         super.onResume()
+        updateAuthText()
+    }
 
+    private fun updateAuthText() {
         val authStatusText = findViewById<TextView>(R.id.auth_status)
         authStatusText.text = when (Studyplus.instance.isAuthenticated(this)) {
             true -> getString(R.string.status_authenticated)

sdk-example-kt/src/main/res/layout/activity_main.xml

@@ -35,6 +35,17 @@
             android:layout_width="match_parent"
             android:layout_height="24dp" />
 
+        <Button
+            android:id="@+id/cancel_auth"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            android:padding="8dp"
+            android:text="@string/cancel_auth_button" />
+
+        <Space
+            android:layout_width="match_parent"
+            android:layout_height="24dp" />
+
         <Button
             android:id="@+id/post_study_record"
             android:layout_width="match_parent"

sdk-example-kt/src/main/res/values/strings.xml

@@ -5,6 +5,7 @@
     <string name="status_authenticated">認証済</string>
 
     <string name="start_auth_button">認証画面を開く</string>
+    <string name="cancel_auth_button">認証を解除する</string>
     <string name="post_study_record_button">投稿！</string>
 
     <string name="consumer_key"></string>