Android Kotlin 액티비티 전환 - intent, putExtra

 

 

 

 

 

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1. 결 과

 

결과 화면

 

 

 

 

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2. activity_main.xml

 

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Layout 1"
        android:textSize="30sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:onClick="next"
        android:text="Next Page"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/text" />

</androidx.constraintlayout.widget.ConstraintLayout>

초기 화면

 

 

 

 

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3. activity_main2.xml

 

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity2">

    <TextView
        android:id="@+id/text2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Layout 2"
        android:textAlignment="center"
        android:textSize="30sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

결과 화면

 

 

 

 

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4. MainActiviy.kt

 

package com.example.myapplication

import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
    }

    fun next(v: View) {
        val send = Intent(this, MainActivity2::class.java).apply {
            putExtra("msg", "Hi~")
        }
        send.putExtra("msg2", "Bye")
        startActivity(send)
    }
}

 

- next 함수를 생성하여 버튼 click 시 호출되도록 한다.

 

 

- Intent 선언 시 MainActivity2을 주어 이동할 곳을 지정하며 putExtra를 사용하여 값을 넘길 수 있다.

 

 

- startActivity 를 사용하여 지정한 Activity를 시작함으로써 액티비티가 전환된다.

 

 

 

 

 

 

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5. MainActivity2.kt

 

package com.example.myapplication

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.TextView

class MainActivity2 : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main2)

        val textView = findViewById<TextView>(R.id.text2)
        textView.text = "${textView.text.toString()}\n${intent.getStringExtra("msg")}"
    }
}

 

- MainActivity에서 putExtra로 보내었던 값을

 

intent.getStringExtra( key )

 

로 읽을 수 있다.

 

 

 

 

 

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6. 참 조

 

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