change HorizontalAdapter to kotlin

app/src/main/java/com/frank/ffmpeg/adapter/HorizontalAdapter.java

@@ -1,79 +0,0 @@
-package com.frank.ffmpeg.adapter;
-
-import android.graphics.Color;
-
-import androidx.annotation.NonNull;
-import androidx.recyclerview.widget.RecyclerView;
-
-import android.util.Log;
-import android.view.LayoutInflater;
-import android.view.View;
-import android.view.ViewGroup;
-import android.widget.Button;
-
-import com.frank.ffmpeg.R;
-import com.frank.ffmpeg.listener.OnItemClickListener;
-
-import java.util.List;
-
-/**
- * the horizontal adapter of RecyclerView
- * Created by frank on 2018/6/6.
- */
-
-public class HorizontalAdapter extends RecyclerView.Adapter {
-
-    private List<String> itemList;
-    private OnItemClickListener onItemClickListener;
-    private int lastClickPosition;
-
-    public HorizontalAdapter(List<String> itemList) {
-        this.itemList = itemList;
-    }
-
-    public void setOnItemClickListener(OnItemClickListener onItemClickListener) {
-        this.onItemClickListener = onItemClickListener;
-    }
-
-    @NonNull
-    @Override
-    public RecyclerView.ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
-        return new OkViewHolder(LayoutInflater.from(parent.getContext()).
-                inflate(R.layout.item_select, parent, false));
-    }
-
-    @Override
-    public void onBindViewHolder(RecyclerView.ViewHolder holder, int position) {
-        final OkViewHolder okViewHolder = (OkViewHolder) holder;
-        okViewHolder.btn_select.setText(itemList.get(position));
-        okViewHolder.btn_select.setTextColor(Color.DKGRAY);
-        if (onItemClickListener != null) {
-            okViewHolder.btn_select.setOnClickListener(new View.OnClickListener() {
-                @Override
-                public void onClick(View v) {
-                    notifyItemChanged(lastClickPosition);
-                    Log.i("onBindViewHolder", "lastClickPosition=" + lastClickPosition);
-                    //设置当前选中颜色
-                    okViewHolder.btn_select.setTextColor(Color.BLUE);
-                    onItemClickListener.onItemClick(okViewHolder.getAdapterPosition());
-                    lastClickPosition = okViewHolder.getAdapterPosition();
-                }
-            });
-        }
-    }
-
-    @Override
-    public int getItemCount() {
-        return itemList != null ? itemList.size() : 0;
-    }
-
-    private class OkViewHolder extends RecyclerView.ViewHolder {
-        Button btn_select;
-
-        OkViewHolder(View itemView) {
-            super(itemView);
-            btn_select = itemView.findViewById(R.id.btn_select);
-        }
-    }
-
-}

app/src/main/java/com/frank/ffmpeg/adapter/HorizontalAdapter.kt

@@ -0,0 +1,57 @@
+package com.frank.ffmpeg.adapter
+
+import android.graphics.Color
+import androidx.recyclerview.widget.RecyclerView
+
+import android.util.Log
+import android.view.LayoutInflater
+import android.view.View
+import android.view.ViewGroup
+import android.widget.Button
+
+import com.frank.ffmpeg.R
+import com.frank.ffmpeg.listener.OnItemClickListener
+
+/**
+ * the horizontal adapter of RecyclerView
+ * Created by frank on 2018/6/6.
+ */
+
+class HorizontalAdapter(private val itemList: List<String>?) : RecyclerView.Adapter<RecyclerView.ViewHolder>() {
+    private var onItemClickListener: OnItemClickListener? = null
+    private var lastClickPosition: Int = 0
+
+    fun setOnItemClickListener(onItemClickListener: OnItemClickListener) {
+        this.onItemClickListener = onItemClickListener
+    }
+
+    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
+        return OkViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.item_select, parent, false))
+    }
+
+    override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
+        val okViewHolder = holder as OkViewHolder
+        okViewHolder.btnSelect.text = itemList!![position]
+        okViewHolder.btnSelect.setTextColor(Color.DKGRAY)
+        if (onItemClickListener != null) {
+            okViewHolder.btnSelect.setOnClickListener {
+                notifyItemChanged(lastClickPosition)
+                Log.i("onBindViewHolder", "lastClickPosition=$lastClickPosition")
+                //select the current color
+                okViewHolder.btnSelect.setTextColor(Color.BLUE)
+                onItemClickListener!!.onItemClick(okViewHolder.adapterPosition)
+                lastClickPosition = okViewHolder.adapterPosition
+            }
+        }
+    }
+
+    override fun getItemCount(): Int {
+        return itemList?.size ?: 0
+    }
+
+    private inner class OkViewHolder internal constructor(itemView: View) : RecyclerView.ViewHolder(itemView) {
+        internal var btnSelect: Button = itemView.findViewById(R.id.btn_select)
+
+    }
+
+}