Android 프로그래밍 2

1. 새프로젝트 생성

프로젝트명 : FragmentTest2

2. MainActivity와 레이아웃 수정

파일명 : 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"
    android:id="@+id/host">

</androidx.constraintlayout.widget.ConstraintLayout>

파일명 : MainActivity.kt

package kr.co.leelab.fragmenttest2

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.fragment.app.Fragment

class MainActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        // Initially display the first fragment in main activity
        // Here we do not pass any arguments
        replaceFragment(FirstFragment())
    }
}

// Extension function to replace fragment
fun AppCompatActivity.replaceFragment(fragment: Fragment){
    val fragmentManager = supportFragmentManager
    val transaction = fragmentManager.beginTransaction()
    transaction.replace(R.id.host,fragment)
    transaction.addToBackStack(null)
    transaction.commit()
}

3. 첫번째 래이아웃과 Fragment 클래스 추가

파일명 : fragment_first.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"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:text="First Fragment"
        android:textAppearance="@style/TextAppearance.AppCompat.Large"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:padding="25dp"
        />
    <Button
        android:id="@+id/btnNavigate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="Go To Second Fragment"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        />
</androidx.constraintlayout.widget.ConstraintLayout>

파일명 : FirstFragment.kt

package kr.co.leelab.fragmenttest2

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.fragment.app.Fragment

class FirstFragment : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        val v =  inflater.inflate(R.layout.fragment_first, container, false)

        // Get the activity and widget
        val context = activity as AppCompatActivity
        val btnNavigate: Button = v.findViewById(R.id.btnNavigate)
        val textView: TextView = v.findViewById(R.id.textView)


        // Get the arguments from the caller fragment/activity
        val name = arguments?.getString("name")
        val age = arguments?.getInt("age")

        name?.let {
            textView.append("\nName: $name")
        }

        age?.let {
            textView.append("\nAge: $it")
        }


        // Replace fragment
        btnNavigate.setOnClickListener {
            // Pass data to fragment
            val args = Bundle()
            // Send string data as key value format
            args.putString("color","#FFFF00")
            val fragment = SecondFragment()
            fragment.arguments = args

            context.replaceFragment(fragment)
        }

        return v
    }
}

4. 두번째 래이아웃과 Fragment 클래스 추가

파일명 : fragment_second.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"
    android:layout_width="match_parent"
    android:layout_height="match_parent">
    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:text="Second Fragment"
        android:textAppearance="@style/TextAppearance.AppCompat.Large"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        android:padding="25dp"
        />
    <Button
        android:id="@+id/btnNavigate"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="24dp"
        android:text="Go To First Fragment"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/textView"
        />
</androidx.constraintlayout.widget.ConstraintLayout>

파일명 : SecondFragment.kt

package kr.co.leelab.fragmenttest2

import android.graphics.Color
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.fragment.app.Fragment

class SecondFragment : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // Inflate the layout for this fragment
        val v =  inflater.inflate(R.layout.fragment_second, container, false)

        // Get the activity and widget
        val context = activity as AppCompatActivity
        val btnNavigate: Button = v.findViewById(R.id.btnNavigate)
        val textView: TextView = v.findViewById(R.id.textView)

        // Receive the data from caller fragment/activity
        val color = arguments?.getString("color")
        color?.let {
            textView.setBackgroundColor(Color.parseColor(it))
        }

        // Replace fragment
        btnNavigate.setOnClickListener {
            val name = "Junwon Lee"
            val age = 25
            val bundle = Bundle()
            bundle.putString("name",name)
            bundle.putInt("age",age)
            val fragment = FirstFragment()
            fragment.arguments = bundle

            // Call the extension function for fragment transaction
            context.replaceFragment(fragment)
        }

        return v
    }
}

5. 실행