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KotlinでArrayList

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ArrayListのテスト

データを入力、削除をするアプリケーション

まずはコードから


Main.kt

import android.support.v7.app.AppCompatActivity

import android.os.Bundle
import android.widget.ArrayAdapter
import android.widget.Button
import android.widget.ListAdapter
import android.widget.ListView
import android.widget.EditText

class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val input = findViewById(R.id.input1) as Button
val delete = findViewById(R.id.saku) as Button
val simpleListView: ListView = findViewById(R.id.simpleListView) as ListView
val adapter = ArrayAdapter<String>(this, android.R.layout.simple_list_item_1)
simpleListView.adapter = adapter as ListAdapter
input.setOnClickListener {
val edit = findViewById(R.id.editex) as EditText
adapter.add(edit.text.toString())
}
delete.setOnClickListener {
val edit = findViewById(R.id.editex) as EditText
adapter.remove(edit.text.toString())
}
}
}


次にXML


activity_main.xml

<?xml version="1.0" encoding="utf-8"?>

<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.nimani.listas.MainActivity">

<ListView
android:id="@+id/simpleListView"
android:layout_width="wrap_content"
android:layout_height="370dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.517"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0" />

<Button
android:id="@+id/input1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="16dp"
android:layout_marginLeft="16dp"
android:text="入力"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
tools:text="入力" />

<EditText
android:id="@+id/editex"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:ems="10"
android:inputType="textPersonName"
android:text="Name"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.502"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.831" />

<Button
android:id="@+id/saku"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginBottom="16dp"
android:layout_marginRight="16dp"
android:text="削除"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintRight_toRightOf="parent" />

</android.support.constraint.ConstraintLayout>


スクリーンショット (161).png

ListViewを使うためにはadapterが必要でadapterを使うことでListViewに追加や削除をすることができる