android - 如何在 Binding Adapter 中将此 java 代码写入 kotlin
问题描述
我在 lang (java) 中用 onBindViewHolder 编写了几行代码。我正在尝试在 Binding Adapter 的 kotlin 中编写确切的代码，但我无法编写
EarthQuakeAdapter( JAVA) .. 我试过了，但我无法编写相同的代码来从 onBindViewHolder(JAVA lang) 方法中获取 MagarCircle 、 PrimaryLocation 和 LocationOffSet 到 kotlin 中的绑定适配器，我在下面发布了
public class EarthquakeAdapter extends RecyclerView.Adapter<EarthquakeAdapter.MyViewHolder> {
@Override
public void onBindViewHolder(@NonNull MyViewHolder holder, int i) {
Properties properties = this.mData.get(i).getProperties();
double earthquakeMagnitude = properties.getMag();
DecimalFormat decimalFormat = new DecimalFormat("0.0");
String formattedMagnitude = decimalFormat.format(earthquakeMagnitude);
holder.tvMagnitude.setText(formattedMagnitude);
// Set the proper background color on the magnitude circle.
// Fetch the background from the TextView, which is a GradientDrawable.
holder.magnitudeCircle = (GradientDrawable) holder.tvMagnitude.getBackground();
//Get the appropriate background color based on the current earthquake magnitude
int magnitudecolor = getMagnitudeColor(properties.getMag());
//Set the color on the magnitude circle
holder.magnitudeCircle.setColor(magnitudecolor);
//Get the original location string from the earthquake object ,
// which can be in the format of "5km N of Cairo, Egypt" or "Pacific-Antartic Ridge' .
//If the original location String (i.e, 5km of Cairo , Egypt ) contains
//a primary location (Cario, Egypt) and a location offset (5km of that city )
//then store the primary location separately from the location offset in 2 strings,
//so they can be displayed in two TextViews.
String originalLocation = properties.getPlace();
//Check whether the originalLocation string contain the "of" text
if (originalLocation.contains("of")) {
//Split the string into different parts (as an array of strings)
//based on the "of" text. We expect an array of two strings, where
// the first string will , be " 5km N" and the second string will be 'Cairo Egypt"
String[] parts = originalLocation.split("of");
//location offset should be "5km N" + " of " ---> "5km N of'
//Primary location should be "Cairo Egypt"
holder.tvLocationOffSet.setText(parts[0] + "of");
holder.tvPrimaryLocation.setText(parts[1]);
} else {
//otherwise , there is no " of " text in the originalLocation string .
//Hence, the default location offset to say " Near the"
holder.tvLocationOffSet.setText("Near The");
holder.tvPrimaryLocation.setText(originalLocation);
}
}
public static class MyViewHolder extends RecyclerView.ViewHolder {
TextView tvMagnitude, tvLocationOffSet, tvPrimaryLocation,
GradientDrawable magnitudeCircle;
public MyViewHolder(@NonNull View itemView) {
super(itemView);
tvMagnitude = itemView.findViewById(R.id.magnitude);
tvLocationOffSet = itemView.findViewById(R.id.location_offset);
tvPrimaryLocation = itemView.findViewById(R.id.primary_location);
}
}
private int getMagnitudeColor(double magnitude) {
int magnitudeColorResourceId;
int magnitudeFloor = (int) Math.floor(magnitude);
switch (magnitudeFloor) {
case 0:
case 1:
magnitudeColorResourceId = R.color.magnitude1;
break;
case 2:
magnitudeColorResourceId = R.color.magnitude2;
break;
case 3:
magnitudeColorResourceId = R.color.magnitude3;
break;
default:
magnitudeColorResourceId = R.color.magnitude10plus;
break;
}
return ContextCompat.getColor(mContext, magnitudeColorResourceId);
}
}
BindingAdapter.kt(KOTLIN)
@BindingAdapter("listData")
fun bindRecyclerView(recyclerView: RecyclerView, data: EarthquakeResponse?) {
val adapter = recyclerView.adapter as RecyclerviewAdapter
if (data != null) {
adapter.submitList(data.features?.toList())
}
}
@BindingAdapter("magnitude")
fun bindAuthor(textView: TextView, magName : Double) {
val decimalFormat = DecimalFormat("0.0")
val formattedMagnitude = decimalFormat.format(magName)
textView.setText(formattedMagnitude.toString())
}
@BindingAdapter("place")
fun bindTitle(textView: TextView, titlePlace : String) {
textView.setText(titlePlace)
// if (titlePlace.contains("of")) {
// @BindingAdapter("placeone")
// fun bindPlaceOne(textView: TextView, titlePlace: String) {
// var parts = titlePlace.split("of").toString()
// textView.setText(parts[0] + "of")
//
// @BindingAdapter("placetwo")
// fun bindPlaceTwo(textView: TextView, titlePlace: String) {
// textView.setText(parts[1].toString())
// }
// }
//
// } else {
// @BindingAdapter("placeone")
// fun bindPlaceOne(textView: TextView, titlePlace: String) {
//
// textView.setText( "NEAR THE") }
//
// @BindingAdapter("placetwo")
// fun bindPlaceTwo(textView: TextView, titlePlace: String) {
// textView.setText(titlePlace)
// }
// }
}
@BindingAdapter("time")
fun bindTime(textView: TextView, titleTime :Long) {
// SimpleDateFormat timeFormat = new SimpleDateFormat("h:mm a");
val timeFormat = SimpleDateFormat("h:mm a")
val formattedTime = timeFormat.format(titleTime)
textView.setText(formattedTime.toString())
}
@BindingAdapter("date")
fun bindDate(textView: TextView, titleTime :Long) {
val timeFormat = SimpleDateFormat("LLL dd, yyyy")
val formattedDate = timeFormat.format(titleTime)
textView.setText(formattedDate.toString())
}
RecyclerviewAdapter.kt
class RecyclerviewAdapter() : ListAdapter<Feature, RecyclerviewAdapter.EarthquakePropertyViewHolder>(DiffCallback()) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): EarthquakePropertyViewHolder {
return EarthquakePropertyViewHolder.from(parent)
}
override fun onBindViewHolder(holder: EarthquakePropertyViewHolder, position: Int) {
val item = getItem(position)
holder.bind(item)
}
class EarthquakePropertyViewHolder private constructor(val binding: EarthquakeRawBinding) : RecyclerView.ViewHolder(binding.root) {
fun bind(books: Feature) {
binding.property = books
binding.executePendingBindings()
}
companion object {
fun from(parent: ViewGroup): EarthquakePropertyViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
val view = EarthquakeRawBinding.inflate(layoutInflater, parent, false)
return EarthquakePropertyViewHolder(view)
}
}
}
}
class DiffCallback : DiffUtil.ItemCallback<Feature>() {
override fun areItemsTheSame(oldItem: Feature, newItem: Feature): Boolean {
return oldItem === newItem
}
override fun areContentsTheSame(oldItem: Feature, newItem: Feature): Boolean {
return oldItem == newItem
}
}
Earthquake_raw.xml
<layout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
xmlns:app="http://schemas.android.com/apk/res-auto" >
<data>
<variable
name="property"
type="com.example.kotlinearthquake.network.Feature" />
</data>
<LinearLayout
android:id="@+id/container"
android:layout_width="match_parent"
android:layout_height="150dp"
android:orientation="horizontal"
android:paddingStart="16dp"
android:paddingLeft="16dp"
android:paddingEnd="16dp"
android:paddingRight="16dp">
<TextView
android:id="@+id/magnitude"
android:layout_width="36dp"
android:layout_height="36dp"
android:layout_gravity="center_vertical"
android:background="@drawable/magnitude_circle"
android:fontFamily="sans-serif-medium"
android:gravity="center"
android:textColor="@android:color/black"
android:textSize="16sp"
app:magnitude="@{property.properties.mag}"
tools:text="8.9" />
<LinearLayout
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:layout_weight="1"
android:orientation="vertical">
<TextView
android:id="@+id/location_offset"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ellipsize="end"
android:fontFamily="sans-serif-medium"
android:maxLines="1"
android:textAllCaps="true"
android:textColor="@android:color/black"
android:textSize="12sp"
tools:text="30km S of" />
<TextView
android:id="@+id/primary_location"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ellipsize="end"
android:maxLines="2"
android:textColor="@android:color/black"
android:textSize="12sp"
app:place="@{property.properties.place}"
tools:text="Long placeholder that should wrap to more than 2 line of text" />
</LinearLayout>
<LinearLayout
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:layout_marginStart="16dp"
android:layout_marginLeft="16dp"
android:orientation="vertical">
<TextView
android:id="@+id/date"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="end"
android:textColor="@color/textColorEarthquakeDetails"
android:textSize="12sp"
app:date="@{property.properties.time}"
tools:text="Mar 6, 2010" />
<TextView
android:id="@+id/time"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="end"
android:textColor="@color/textColorEarthquakeDetails"
android:textSize="12sp"
app:time="@{property.properties.time}"
tools:text="3:00 PM" />
</LinearLayout>
</LinearLayout>
</layout>
请帮助我，我还是 Kotlin 编程的新手。
解决方案
基本上规则是反转语法。如果你有String originalLocation = properties.getPlace();kotlin 那将是var/val originalLocation: String = properties.getPlace(). Var 代表变化的变量，val 代表不变的值。您可以绕过定义对象的类型，因为 kotlin 足够聪明，可以知道不同类型的初始化属性。void是fun并且您不需要指定它是否是公共的，因为它是默认的，除非您另有说明。class两者都是相同的，并且函数中的变量是反向声明的， (@NonNull MyViewHolder holder, int i)所以(holder: MyViewHolder, i: Int).
当然，Android Studio 有这个很棒的选项，当你将 java 代码复制到 kotlin 文件时，它会询问你是否要将其更改为 kotlin。
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