Recyclerview 卡片项目 Onclick Kotlin [英] Recyclerview Card Item Onclick Kotlin

问题描述

我想在用户分别点击 cardview 时创建一个新的意图/活动，我想知道如何在 kotlin 中做到这一点.我注意到大多数教程都是用 Java 编写的，而我是一个没有学过 Java 的学生.

包 com.example.ttshfypj.adapters导入 androidx.fragment.app.Fragment导入 android.view.View导入 android.view.LayoutInflater导入 android.view.ViewGroup导入 androidx.recyclerview.widget.RecyclerView导入 com.example.ttshfypj.data_class.medications导入 android.widget.ImageView导入 android.widget.TextView导入 com.example.ttshfypj.R导入 com.squareup.picasso.Picasso导入 kotlinx.android.synthetic.main.list_medication.view.*类药物适配器(瓦尔药物列表:ArrayList<药物>):RecyclerView.Adapter(){覆盖乐趣 onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {val v = LayoutInflater.from(parent.context).inflate(R.layout.list_medication, parent, false)返回 ViewHolder(v)}覆盖乐趣 getItemCount(): Int {返回药物清单.大小}覆盖乐趣 onBindViewHolder(holder: ViewHolder, position: Int) {val 药物组:药物 = 药物列表[位置]持有人?.medicationnamevar?.text = druggroup.medicineN持有人?.medicationschedulevar?.text = druggroup.MedicineTimeval imagemedicine = holder?.itemView?.medicationimageviewPicasso.get().load(medicationgroup.MedicineImage).into(imagemedicine)}类 ViewHolder(itemView: View) :RecyclerView.ViewHolder(itemView) {val drugnamevar = itemView.findViewById(R.id.medicationname) as TextViewval drugchedulevar = itemView.findViewById(R.id.medicationschedule) 作为 TextView}}

解决方案

如果您正在使用 kotlin，您还可以使用方法引用，您可以直接在适配器内部传递要调用的方法，并且可以直接在那里调用它.

Activity.kt

<预><代码>适配器(this::itemClickHandler)；私人乐趣 itemClickHandler(int position){//你的逻辑在这里}

Adapter.kt

class Adapter(val itemClickHandler:(Int)->Unit):RecyclerView.Adapter(){覆盖乐趣 onBindViewHolder(){//你可以像这样在这里调用它itemClickHandler.invoke(adapterPosition);}}

请参考此完整代码

MainActivity.kt

包 com.example.myapplication导入 androidx.appcompat.app.AppCompatActivity导入 android.os.Bundle导入 android.util.Log导入 androidx.recyclerview.widget.LinearLayoutManager导入 kotlinx.android.synthetic.main.activity_main.*类 MainActivity : AppCompatActivity() {覆盖 fun onCreate(savedInstanceState: Bundle?) {super.onCreate(savedInstanceState)setContentView(R.layout.activity_main)val list = mutableListOf()for(i 在 1..25){list.add(Items(CHILD,"Child"))}与(rvList){layoutManager = LinearLayoutManager(this@MainActivity)适配器 = 适配器(列表，这个@MainActivity::onItemClickHandler)}}私人乐趣 onItemClickHandler(position:Int){Log.d("***","${position}");//在这里你可以开始一个新的意图来点击项目打开一个新的活动}}

适配器代码如下

包 com.example.myapplication导入 android.view.LayoutInflater导入 android.view.View导入 android.view.ViewGroup导入 androidx.recyclerview.widget.RecyclerView导入 kotlinx.android.synthetic.main.layout_child.view.*导入 kotlinx.android.synthetic.main.layout_header.view.*const val 头 = 1;const val 儿童 = 2;数据类项目(val 类型:Int，val 文本:String)类适配器(私有 val 列表:List, val itemClickHandler: (Int) -> Unit):RecyclerView.Adapter() {覆盖乐趣 onCreateViewHolder(parent: ViewGroup, viewType: Int): HeaderViewHolder {val headerView =LayoutInflater.from(parent.context).inflate(R.layout.layout_header, parent, false)val headerViewHolder = HeaderViewHolder(headerView)headerView.setOnClickListener {itemClickHandler.invoke(headerViewHolder.adapterPosition)}返回 headerViewHolder}覆盖乐趣 getItemCount(): Int = list.size覆盖乐趣 onBindViewHolder(holder: HeaderViewHolder, position: Int) {持有人.onBind(列表[位置].文本)}内部类 HeaderViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {有趣的 onBind(文本:字符串){itemView.tvHeader.text = 文本}}}

希望这对你有帮助，你可以关注

I want to create a new intent/activity when the user clicks on a cardview respectively and i was wondering how does one do it in kotlin. i noticed most tutorials are in java and i'm a student who did not learn java.

package com.example.ttshfypj.adapters

import androidx.fragment.app.Fragment
import android.view.View
import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import com.example.ttshfypj.data_class.medications
import android.widget.ImageView
import android.widget.TextView
import com.example.ttshfypj.R

import com.squareup.picasso.Picasso
import kotlinx.android.synthetic.main.list_medication.view.*

class medicationAdapter (val medicationlist: ArrayList<medications>) : RecyclerView.Adapter<medicationAdapter.ViewHolder>() {

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
        val v = LayoutInflater.from(parent.context).inflate(R.layout.list_medication, parent, false)
        return ViewHolder(v)
    }

    override fun getItemCount(): Int {
        return medicationlist.size
    }

    override fun onBindViewHolder(holder: ViewHolder, position: Int) {
        val medicationgroup: medications = medicationlist[position]
        holder?.medicationnamevar?.text = medicationgroup.medicineN
        holder?.medicationschedulevar?.text = medicationgroup.MedicineTime
        val imagemedicine = holder?.itemView?.medicationimageview
        Picasso.get().load(medicationgroup.MedicineImage).into(imagemedicine)

    }
    class ViewHolder(itemView: View) :RecyclerView.ViewHolder(itemView) {
        val medicationnamevar = itemView.findViewById(R.id.medicationname) as TextView
        val medicationschedulevar = itemView.findViewById(R.id.medicationschedule) as TextView
    }




}

解决方案

If you are using kotlin you can also use method reference where you directly pass a method to be called inside the adapter and you can directly invoke it there.

Activity.kt

Adapter(this::itemClickHandler);

private fun itemClickHandler(int position){
// your logic here
}

Adapter.kt

class Adapater(val itemClickHandler:(Int)->Unit):RecyclerView.Adapter(){

   override fun onBindViewHolder(){
      //you can invoke it here like this
     itemClickHandler.invoke(adapterPosition);
    } 

}

please refer this full code

MainActivity.kt

package com.example.myapplication

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import androidx.recyclerview.widget.LinearLayoutManager
import kotlinx.android.synthetic.main.activity_main.*

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        val list = mutableListOf<Items>()
        for(i in 1..25){
            list.add(Items(CHILD,"Child"))
        }
        with(rvList) {
            layoutManager = LinearLayoutManager(this@MainActivity)
            adapter = Adapter(list, this@MainActivity::onItemClickHandler)
        }

    }

     private fun onItemClickHandler(position:Int){
         Log.d("***","${position}");
        //here you can start a new intent to open a new activity on click of item

    }
}

The adapter code is as following

package com.example.myapplication

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.layout_child.view.*
import kotlinx.android.synthetic.main.layout_header.view.*

const val HEADER = 1;
const val CHILD = 2;

data class Items(val type: Int, val text: String)

class Adapter(private val list: List<Items>, val itemClickHandler: (Int) -> Unit) :
    RecyclerView.Adapter<Adapter.HeaderViewHolder>() {


    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): HeaderViewHolder {
        val headerView =
            LayoutInflater.from(parent.context).inflate(R.layout.layout_header, parent, false)
        val headerViewHolder = HeaderViewHolder(headerView)
        headerView.setOnClickListener {
            itemClickHandler.invoke(headerViewHolder.adapterPosition)
        }
        return headerViewHolder
    }

    override fun getItemCount(): Int = list.size

    override fun onBindViewHolder(holder: HeaderViewHolder, position: Int) {
        holder.onBind(list[position].text)

    }

    inner class HeaderViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {

        fun onBind(text: String) {
            itemView.tvHeader.text = text
        }
    }


}

Hope this helps and you are able to follow

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