1. Kotlin で Android アプリを作ってみた
bina1204
1

2. アジェンダ
• 自己紹介
• Kotlin で Android アプリを作ってみた
• Java と Kotlin の比較
• まとめ
2

3. 自己紹介
3

4. プロフィール
びな
@bina1204
http://gsbina.com
4

5. Kotlin 初心者です
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6. Kotlin で Android アプリを作ってみた
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7. Kotlin を覚える
Kotlin Advent Calendar 2012 (全部俺) : ATND
http://atnd.org/events/34627
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8. Kotlin の Android アプリ開発の準備
8.2 Androidアプリ開発 - プログラミング言語Kotlin
解説
https://sites.google.com/site/tarokotlin/chap8/sec82
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9. アプリを作ってみた
タップすると
スリープする
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10. アプリを作ってみた
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11. Java と Kotlin の比較
11

12. AdminReceiver.Java
package com.gsbina.android.sleepnow;
import android.app.admin.DeviceAdminReceiver;
public class AdminReceiver extends DeviceAdminReceiver {
}
12

13. AdminReceiver.kt
package com.gsbina.android.sleepnow
import android.app.admin.DeviceAdminReceiver
public class AdminReceiver: DeviceAdminReceiver() {
}
13

14. CreateShortcutActivity.Java
@Override
protected void onResume() {
super.onResume();
final Intent sleepIntent = new Intent(PhoneSleepActivity.ACTION_SLEEP);
final Intent shortcutIntent = new Intent("com.android.launcher.action.INSTALL_SHORTCUT");
shortcutIntent.putExtra(Intent.EXTRA_SHORTCUT_INTENT, sleepIntent);
shortcutIntent.putExtra(Intent.EXTRA_SHORTCUT_NAME, "Sleep Now");
shortcutIntent.putExtra(Intent.EXTRA_SHORTCUT_ICON_RESOURCE, R.drawable.ic_launcher);
sendBroadcast(shortcutIntent);
finish();
}
14

15. CreateShortcutActivity.Kt
protected override fun onResume() {
super<Activity>.onResume()
val sleepIntent = Intent(PhoneSleepActivity.ACTION_SLEEP)
val shortcutIntent = Intent("com.android.launcher.action.INSTALL_SHORTCUT")
shortcutIntent.putExtra(Intent.EXTRA_SHORTCUT_INTENT, sleepIntent)
shortcutIntent.putExtra(Intent.EXTRA_SHORTCUT_NAME, "Sleep Now");
shortcutIntent.putExtra(Intent.EXTRA_SHORTCUT_ICON_RESOURCE, R.drawable.ic_launcher)
sendBroadcast(shortcutIntent)
finish()
}
15

16. PhoneSleepActivity.java
@Override
protected void onResume() {
super.onResume();
final DevicePolicyManager dpm = (DevicePolicyManager)getSystemService(DEVICE_POLICY_SERVICE);
if (dpm.isAdminActive(new AdminReceiver().getWho(this))) {
// スリープする
dpm.lockNow();
} else {
Toast.makeText(this, "Cannot sleep", Toast.LENGTH_SHORT).show();
startActivity(new Intent(this, MainActivity.class));
}
finish();
}
public static final String ACTION_SLEEP = "com.gsbina.android.sleepnow.action.SLEEP";
16

17. PhoneSleepActivity.Kt
protected override fun onResume() {
super<Activity>.onResume()
val dpm = getSystemService(Context.DEVICE_POLICY_SERVICE) as DevicePolicyManager
if (dpm.isAdminActive(AdminReceiver().getWho(this))) {
// スリープする
dpm.lockNow();
} else {
Toast.makeText(this, "Cannot sleep", Toast.LENGTH_SHORT)?.show()
startActivity(Intent(this, javaClass<MainActivity>()))
}
finish()
}
class object {
val ACTION_SLEEP = "com.gsbina.android.sleepnow.action.SLEEP"
}
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18. MainActivity.java
private final MainActivity mSelf = this;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
setUpView();
}
private DevicePolicyManager mDevicePolicyManager;
private void setUpView() {
findViewById(R.id.device_admin).setOnClickListener(new OnClickDeviceAdmin());
findViewById(R.id.btn_create_shortcut).setOnClickListener(new OnClickCreateShortcut());
findViewById(R.id.btn_display_notification).setOnClickListener(new OnClickDisplayNotification());
findViewById(R.id.btn_hide_notification).setOnClickListener(new OnClickHideNotification());
findViewById(R.id.btn_sleep).setOnClickListener(new OnClickSleep());
findViewById(R.id.btn_uninstall).setOnClickListener(new OnClickUninstall());
}
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19. MainActivity.kt
val mSelf = this
protected override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.main)
setUpView()
}
var mDevicePolicyManager: DevicePolicyManager? = null
private fun setUpView() {
findViewById(R.id.device_admin)?.setOnClickListener(OnClickDeviceAdmin())
findViewById(R.id.btn_create_shortcut)?.setOnClickListener(OnClickCreateShortcut())
findViewById(R.id.btn_display_notification)?.setOnClickListener(OnClickDisplayNotification())
findViewById(R.id.btn_hide_notification)?.setOnClickListener(OnClickHideNotification())
findViewById(R.id.btn_sleep)?.setOnClickListener(OnClickSleep())
findViewById(R.id.btn_uninstall)?.setOnClickListener(OnClickUninstall())
}
19

20. MainActivity.java
private class OnClickDeviceAdmin implements OnClickListener {
@Override
public void onClick(View v) {
final Switch s = (Switch) v;
if (s.isChecked()) {
activateDeviceAdmin();
} else {
mDevicePolicyManager.removeActiveAdmin(new AdminReceiver().getWho(mSelf));
new Handler().postDelayed(new Runnable() {
@Override
public void run() {
updateView();
}
}, 250);
}
}
private void activateDeviceAdmin() {
final Intent intent = new Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN);
final ComponentName name = new AdminReceiver().getWho(mSelf);
intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, name);
startActivity(intent);
}
}
20

21. MainActivity.kt
inner class OnClickDeviceAdmin(): OnClickListener {
public override fun onClick(v: View?) {
val s = v as Switch
if (s.isChecked()) {
activateDeviceAdmin()
} else {
mDevicePolicyManager?.removeActiveAdmin(AdminReceiver().getWho(mSelf))
Handler().postDelayed(Runnable {
updateView()
}, 250)
}
}
private fun activateDeviceAdmin() {
val intent = Intent(DevicePolicyManager.ACTION_ADD_DEVICE_ADMIN)
val name = AdminReceiver().getWho(mSelf)
intent.putExtra(DevicePolicyManager.EXTRA_DEVICE_ADMIN, name)
startActivity(intent)
}
}
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22. APK ファイルの比較
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23. サイズ
Java
約 229KB
Kotlin
約 467KB
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24. classes.dex
Java
android
com
Kotlin
android
com
jet
kotlin
org
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25. AdminReceiver.class(Java)
package com.gsbina.android.sleepnow;
import android.app.admin.DeviceAdminReceiver;
public class AdminReceiver extends DeviceAdminReceiver
{
public AdminReceiver()
{
}
}
25

26. AdminReceiver.class(Kotlin)
package com.gsbina.android.sleepnow;
import android.app.admin.DeviceAdminReceiver;
import jet.JetObject;
public final class AdminReceiver extends DeviceAdminReceiver
implements JetObject
{
public AdminReceiver()
{
}
}
26

27. CreateShortcutActivity.class(Java)
protected void onResume()
{
super.onResume();
Intent intent = new Intent("com.gsbina.android.sleepnow.action.SLEEP");
Intent intent1 = new Intent("com.android.launcher.action.INSTALL_SHORTCUT");
Intent intent2 = intent1.putExtra("android.intent.extra.shortcut.INTENT", intent);
Intent intent3 = intent1.putExtra("android.intent.extra.shortcut.NAME", "Sleep Now");
Intent intent4 = intent1.putExtra("android.intent.extra.shortcut.ICON_RESOURCE", 0x7f020000);
sendBroadcast(intent1);
finish();
}
27

28. CreateShortcutActivity.class(Kotlin)
protected void onResume()
{
super.onResume();
String s = PhoneSleepActivity.object$.getACTION_SLEEP();
Intent intent = new Intent(s);
Intent intent1 = new Intent("com.android.launcher.action.INSTALL_SHORTCUT");
String s1 = Intent.EXTRA_SHORTCUT_INTENT;
Intrinsics.checkFieldIsNotNull(s1, "Intent", "EXTRA_SHORTCUT_INTENT");
Parcelable parcelable = (Parcelable)intent;
Intent intent2 = intent1.putExtra(s1, parcelable);
String s2 = Intent.EXTRA_SHORTCUT_NAME;
Intrinsics.checkFieldIsNotNull(s2, "Intent", "EXTRA_SHORTCUT_NAME");
Intent intent3 = intent1.putExtra(s2, "Sleep Now");
String s3 = Intent.EXTRA_SHORTCUT_ICON_RESOURCE;
Intrinsics.checkFieldIsNotNull(s3, "Intent", "EXTRA_SHORTCUT_ICON_RESOURCE");
int i = R.drawable.ic_launcher;
Intent intent4 = intent1.putExtra(s3, i);
sendBroadcast(intent1);
finish();
}
28

29. PhoneSleepActivity.class(Java)
protected void onResume()
{
super.onResume();
DevicePolicyManager devicepolicymanager = (DevicePolicyManager)getSystemService("device_policy");
android.content.ComponentName componentname = (new AdminReceiver()).getWho(this);
if(devicepolicymanager.isAdminActive(componentname)
{
devicepolicymanager.lockNow();
} else
{
Toast.makeText(this, "Cannot sleep", 0).show();
Intent intent = new Intent(this, com/gsbina/android/sleepnow/MainActivity);
startActivity(intent);
}
finish();
}
public static final String ACTION_SLEEP = "com.gsbina.android.sleepnow.action.SLEEP";
29

30. PhoneSleepActivity.class(Kotlin)
protected void onResume()
{
super.onResume();
String s = Context.DEVICE_POLICY_SERVICE;
Intrinsics.checkFieldIsNotNull(s, "Context", "DEVICE_POLICY_SERVICE");
Object obj = getSystemService(s);
if(obj == null)
throw new TypeCastException("jet.Any? cannot be cast to android.app.admin.DevicePolicyManager");
DevicePolicyManager devicepolicymanager = (DevicePolicyManager)obj;
android.content.ComponentName componentname = (new AdminReceiver()).getWho(this);
if(devicepolicymanager.isAdminActive(componentname))
{
devicepolicymanager.lockNow();
} else
{
Context context = getApplicationContext();
CharSequence charsequence = (CharSequence)"Cannot sleep";
int i = Toast.LENGTH_SHORT;
Toast toast = Toast.makeText(context, charsequence, i);
if(toast != null)
toast.show();
Intent intent = new Intent(this, com/gsbina/android/sleepnow/MainActivity);
startActivity(intent);
}
finish();
}
30

31. PhoneSleepActivity.class(Kotlin)
public static final class object
implements JetObject
{
public final String getACTION_SLEEP()
{
return ACTION_SLEEP;
}
private final String ACTION_SLEEP = "com.gsbina.android.sleepnow.action.SLEEP";
object()
{
}
}
public static final object object$ = new object();
31

32. まとめ
32

33. まとめ
33
final Intent intent = new Intent(this, MainActivity.class);
val intent = Intent(this, javaClass<MainActivity>());

34. まとめ
34
new Runnable() {
@Override
public void run() {
// 処理
}
}
Runnable {
// 処理
}

35. まとめ(定数)
35
public static final String ACTION_SLEEP =
"com.gsbina.android.sleepnow.action.SLEEP";
class object {
val ACTION_SLEEP = "com.gsbina.android.sleepnow.action.SLEEP"
}

36. まとめ
コーディングの量が減る
36
Java Kotlin
MainActivity 3773 3395
AdminReceiver 131 125
CreateShortcutActivity 594 566
PhoneSleepActivity 631 635
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