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+BWBˠ,PUMJOͷ
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DPNNJUͰLPUMJOԽͨ͠13
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LPUMJOԽલʹSFOBNFͷDPNNJUΛೖΕΔ
% mv DetailHeaderView.java DetailHeaderView.kt
% git add -A
% git commit -m 'rename DetailHeaderView.java to DetailHeaderView.kt'
…
% mv DetailHeaderView.kt DetailHeaderView.java
͜ͷޙʹ Convert Java File to Kotlin File ͢Δ
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LUʹSFOBNF͔ͯ͠ΒLPUMJOԽͨ͠13
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LUʹSFOBNF͔ͯ͠ΒLPUMJOԽͨ͠13
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LUʹSFOBNF͔ͯ͠ΒLPUMJOԽͨ͠13
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LUʹSFOBNF͔ͯ͠ΒLPUMJOԽͨ͠13
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$POWFSU+BWB'JMFUP,PUMJO
'JMFͷ͋ͱʹΔ͜ͱ
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Λͳ͘͢
public void addAll(List newItems) {
items.addAll(newItems);
}
Java
fun addAll(newItems: List?) {
items.addAll(newItems!!)
}
Kotlin (Auto Convert)
fun addAll(newItems: List) {
items.addAll(newItems)
}
Kotlin
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ෆཁͳ Λͳ͘͢
public static DetailFragment createInstance(String title) {
DetailFragment fragment = new DetailFragment();
Bundle args = new Bundle();
args.putString(DetailFragment.ARGS_TITLE, title);
fragment.setArguments(args);
return fragment;
}
Java
public void putString(@Nullable String key, @Nullable String value) {
unparcel();
mMap.put(key, value);
}
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Kotlin (Auto Convert)
ෆཁͳ Λͳ͘͢
fun createInstance(title: String?): DetailFragment {
val fragment = DetailFragment()
val args = Bundle()
args.putString(ARGS_TITLE, title)
fragment.arguments = args
return fragment
}
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ෆཁͳ Λͳ͘͢
fun createInstance(title: String): DetailFragment {
val fragment = DetailFragment()
val args = Bundle()
args.putString(ARGS_TITLE, title)
fragment.arguments = args
return fragment
}
Kotlin
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ෆཁͳ ͕ೖΓ͍͢ͱ͜Ζ
w Ҿͷܕ
w Γͷܕ
w ܕύϥϝʔλ
w ྫʣ-JTU4USJOH
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MBUFJOJUWBS
Kotlin (Auto Convert)
class ViewHolder {
private var titleView: TextView? = null
fun init(view: View) {
titleView = view.findViewById(R.id.title_view)
}
fun setTitle(title: String?) {
titleView!!.text = title
}
}
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MBUFJOJUWBS
class ViewHolder {
private lateinit var titleView: TextView
fun init(view: View) {
titleView = view.findViewById(R.id.title_view)
}
fun setTitle(title: String) {
titleView.text = title
}
}
Kotlin
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WBSΛͰ͖Δ͔͗ΓΊΔ
int sum = 0;
for (Item item : items) {
sum += item.getPrice();
}
Java
var sum = 0
for (item in items) {
sum += item.price
}
Kotlin (Auto Convert)
val sum = items.sumOf { it.price }
Kotlin
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LPUMJOTUEMJCΛ͏
w ͍ΖΜͳศར͕ؔ͋ΔͷͰࣗͰ࣮͢ΔલʹௐΑ͏
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fi
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fi
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w
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BU.BQ
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w HFU0S/VMM
w EJTUJODU
EJTUJODU#Z
w DPFSDF"U.PTU
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w BT4FRVFODF
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MFU
Λ͏
LogParams log;
if (title == null) {
log = null;
} else {
log = new LogParams(title);
}
Java
val log = if (title == null) {
null
} else {
LogParams(title)
}
Kotlin (Auto Convert)
val log = title?.let { LogParams(it) }
Kotlin
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BQQMZ
BMTP
TextView titleView = view.findViewById(R.id.title_view);
titleView.setTextSize(16);
titleView.setTextColor(getResources().getColor(R.color.title));
titleView.setText(title);
Java
val titleView = view.findViewById(R.id.title_view)
titleView.textSize = 16f
titleView.setTextColor(resources.getColor(R.color.title))
titleView.text = title
Kotlin (Auto Convert)
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BQQMZ
BMTP
val titleView = view.findViewById(R.id.title_view)
titleView.textSize = 16f
titleView.setTextColor(resources.getColor(R.color.title))
titleView.text = title
Kotlin (Auto Convert)
view.findViewById(R.id.title_view).apply {
textSize = 16f
setTextColor(resources.getColor(R.color.title))
text = title
}
Kotlin
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@Λ͏
okButton.setListener((v, log) -> onClickOk(log));
Java
Kotlin (Auto Convert)
okButton.setListener { v: View?, log: String -> onClickOk(log) }
okButton.setListener { _, log -> onClickOk(log) }
Kotlin
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֦ுؔΛ͏
fun convert(value: A): B {
…
}
Kotlin
ͷ߹
val b = a?.let { convert(it) }
fun A.toB(): B {
…
}
ͷ߹
val b = a?.toB()
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4NBSUDBTU
if (parentFragment instanceof Listener) {
((Listener) parentFragment).onUpdate(title);
}
Java
if (parentFragment is Listener) {
(parentFragment as Listener).onUpdate(title)
}
Kotlin (Auto Convert)
if (parentFragment is Listener) {
parentFragment.onUpdate(title)
}
Kotlin
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BT
if (parentFragment instanceof Listener) {
((Listener) parentFragment).onUpdate(title);
}
Java
if (parentFragment is Listener) {
(parentFragment as Listener).onUpdate(title)
}
Kotlin (Auto Convert)
(parentFragment as? Listener)?.onUpdate(title)
Kotlin
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XIFO
public static ImageUrl create(
String light,
String dark
) {
if (light == null) {
return null;
} else if (dark == null) {
return null;
} else {
return new ImageUrl(light, dark);
}
}
Java Kotlin (Auto Convert)
companion object {
fun create(
light: String?,
dark: String?
): ImageUrl? {
return if (light == null) {
null
} else if (dark == null) {
null
} else {
ImageUrl(light, dark)
}
}
}
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Kotlin (Auto Convert)
XIFO
companion object {
fun create(
light: String?,
dark: String?
): ImageUrl? {
return if (light == null) {
null
} else if (dark == null) {
null
} else {
ImageUrl(light, dark)
}
}
}
companion object {
fun create(
light: String?,
dark: String?
): ImageUrl? {
return when {
light == null -> null
dark == null -> null
else -> ImageUrl(light, dark)
}
}
}
Kotlin
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ؔࢀর
cancelButton.setListener(() -> {
onClickCancel();
return Unit.INSTANCE;
});
Java
cancelButton.setListener {
onClickCancel()
Unit
}
Kotlin (Auto Convert)
cancelButton.setListener(::onClickCancel)
Kotlin
fun setListener(listener: () -> Unit) {
this.listener = listener
}
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$PMMFDUJPOܥ
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Ͱ͖Δ͚ͩ*NNVUBCMF$PMMFDUJPOʹ͢Δ
List log = new ArrayList<>();
for(int i = 0; i < items.size(); i++){
Item item = items.get(i);
log.add(i + ": " +item.getTitle());
}
Java
val log: MutableList = ArrayList()
for (i in items.indices) {
val item = items[i]
log.add(i.toString() + ": " + item.title)
}
Kotlin (Auto Convert)
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Ͱ͖Δ͚ͩ*NNVUBCMF$PMMFDUJPOʹ͢Δ
val log: MutableList = ArrayList()
for (i in items.indices) {
val item = items[i]
log.add(i.toString() + ": " + item.title)
}
Kotlin (Auto Convert)
val log = items.mapIndexed { i, item ->
"$i: ${item.title}"
}
Kotlin
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.VUBCMF$PMMFDUJPOΛެ։͠ͳ͍
public class DataHolder {
public final List items = new ArrayList<>();
public void addAll(List newItems) {
items.addAll(newItems);
}
Java
class DataHolder {
val items: MutableList = ArrayList()
fun addAll(newItems: List?) {
items.addAll(newItems!!)
}
Kotlin (Auto Convert)
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.VUBCMF$PMMFDUJPOΛެ։͠ͳ͍
class DataHolder {
private val _items: MutableList = ArrayList()
val items: List
get() = _items
fun addAll(newItems: List) {
_items.addAll(newItems)
}
}
Kotlin
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"SSBZ-JTU
ˠNVUBCMF-JTU0G
public class DetailFragment extends Fragment {
private List items = new ArrayList<>();
void addItem(String item) {
items.add(item);
}
Java
class DetailFragment : Fragment() {
private val items: MutableList = ArrayList()
fun addItem(item: String) {
items.add(item)
}
Kotlin (Auto Convert)
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"SSBZ-JTU
ˠNVUBCMF-JTU0G
class DetailFragment : Fragment() {
private val items: MutableList = ArrayList()
fun addItem(item: String) {
items.add(item)
}
Kotlin (Auto Convert)
class DetailFragment : Fragment() {
private val items = mutableListOf()
fun addItem(item: String) {
items.add(item)
}
Kotlin
HashMap,
LinkedHashMap → mutableMapOf()
HashSet,
LinkedHashSet → mutableSetOf()
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CVJME-JTU\^
CVJME.BQ\^
ArrayList params = new ArrayList<>();
if (!hasParamA) {
params.add(PARAM_A);
} else {
if (hasParamB) {
params.add(PARAM_B);
} else {
params.add(PARAM_C);
}
}
Java
val params = ArrayList()
if (!hasParamA) {
params.add(PARAM_A)
} else {
if (hasParamB) {
params.add(PARAM_B)
} else {
params.add(PARAM_C)
}
}
Kotlin (Auto Convert)
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CVJME-JTU\^
CVJME.BQ\^
val params = ArrayList()
if (!hasParamA) {
params.add(PARAM_A)
} else {
if (hasParamB) {
params.add(PARAM_B)
} else {
params.add(PARAM_C)
}
}
Kotlin (Auto Convert)
val params = buildList {
if (!hasParamA) {
add(PARAM_A)
} else {
if (hasParamB) {
add(PARAM_B)
} else {
add(PARAM_C)
}
}
}
Kotlin
Immutable
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"OESPJEؔ࿈
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CVOEMF0G
Bundle args = new Bundle();
args.putString(DetailFragment.ARGS_TITLE, title);
fragment.setArguments(args);
Java
val args = Bundle()
args.putString(ARGS_TITLE, title)
fragment.arguments = args
Kotlin (Auto Convert)
fragment.arguments = bundleOf(
ARGS_TITLE to title
)
Kotlin
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5FYU6UJMTJT&NQUZ
ˠJT/VMM0S&NQUZ
val title = args.getString(ARGS_TITLE)
if (!TextUtils.isEmpty(title)) {
…
}
Kotlin (Auto Convert)
val title = args.getString(ARGS_TITLE)
if (!title.isNullOrEmpty()) {
…
}
Kotlin
String title = args.getString(ARGS_TITLE);
if (!TextUtils.isEmpty(title)) {
…
}
Java
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5FYU6UJMTFRVBMT
ˠ
val title = args.getString(ARGS_TITLE)
if (TextUtils.equals(title, current)) {
…
}
Kotlin (Auto Convert)
val title = args.getString(ARGS_TITLE)
if (title == current) {
…
}
Kotlin
String title = args.getString(ARGS_TITLE);
if (TextUtils.equals(title, current)) {
…
}
Java
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CZWJFX.PEFMT
private DetailViewModel viewModel;
@Override
public void onCreate(@Nullable Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
viewModel = new ViewModelProvider(this).get(DetailViewModel.class);
Java
private var viewModel: DetailViewModel? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
viewModel = ViewModelProvider(this).get(DetailViewModel::class.java)
Kotlin (Auto Convert)
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CZWJFX.PEFMT
private var viewModel: DetailViewModel? = null
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
viewModel = ViewModelProvider(this).get(DetailViewModel::class.java)
Kotlin (Auto Convert)
private val viewModel: DetailViewModel by viewModels()
Kotlin
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MBUFJOJUWBSGPSˏ*OKFDU
@AndroidEntryPoint
public class DetailFragment extends Fragment {
@Inject
DetailLogger logger;
Java
@AndroidEntryPoint
class DetailFragment : Fragment() {
@Inject
var logger: DetailLogger? = null
Kotlin (Auto Convert)
@AndroidEntryPoint
class DetailFragment : Fragment() {
@Inject
lateinit var logger: DetailLogger
Kotlin
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νΣοΫϦετ
w ͍ͬͯͳ͍͔
w ෆཁͳ ͍ͬͯͳ͍͔
w MBUFJOJUWBSʹͰ͖Δͱ͜Ζͳ͍͔
w WBMʹͰ͖ΔWBS͍ͬͯͳ͍͔
w ͑ΔTUEMJCͳ͍͔
w MFU
Ͱ؆ܿʹͰ͖Δͱ͜Ζͳ͍͔
w BQQMZ
BMTPͰ·ͱΊΒΕΔॳظԽॲཧͳ͍͔
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νΣοΫϦετ
w @ʹϦωʔϜͰ͖Δͱ͜Ζͳ͍͔
w 4NBSUDBTUʹΑͬͯDBTU͕ෆཁʹͳ͍ͬͯΔͱ͜Ζͳ͍͔
w XIFOΛͬͨ΄͏͕؆ܿʹͳΔͱ͜Ζͳ͍͔
w ؔࢀর͕͔ͭ͑Δͱ͜Ζͳ͍͔
w *NNVUBCMFʹͰ͖Δ.VUBCMFDPMMFDUJPO͕ͬͯͳ͍͔
w .VUBCMFDPMMFDUJPOΛެ։͍ͯ͠ͳ͍͔
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νΣοΫϦετGPS"OESPJE
w CVOEMF0G͕͑Δͱ͜Ζͳ͍͔
w 5FYU6UJMTJT&NQUZ
͕ͬͯͳ͍͔
w 5FYU6UJMTFRVBMT
͕ͬͯͳ͍͔
w CZWJFX.PEFMT
Λ͍ͬͯΔ͔
w !*OKFDU͕͍ͭͨ
fi
FMEMBUFJOJUWBSʹͳ͍ͬͯΔ͔ɹ