Kotlinで簡単に理解！フラグメントの12選

import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment

class SampleFragment : Fragment() {
    // フラグメントのビューを生成する
    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        // フラグメントのレイアウトを関連付ける
        return inflater.inflate(R.layout.fragment_sample, container, false)
    }
}

class SenderFragment : Fragment() {

    fun sendDataToReceiver() {
        val receiverFragment = ReceiverFragment.newInstance("Hello from SenderFragment")
        parentFragmentManager.beginTransaction()
            .replace(R.id.fragment_container, receiverFragment)
            .commit()
    }
}

class ReceiverFragment : Fragment() {
    companion object {
        private const val ARG_MESSAGE = "message"

        fun newInstance(message: String): ReceiverFragment {
            val args = Bundle()
            args.putString(ARG_MESSAGE, message)
            val fragment = ReceiverFragment()
            fragment.arguments = args
            return fragment
        }
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        val message = arguments?.getString(ARG_MESSAGE)
        // ここでmessageを使って何かの処理を行う
    }
}

// MainActivity.kt
class MainActivity : AppCompatActivity() {

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

        val message = "Hello from MainActivity"
        val sampleFragment = SampleFragment.newInstance(message)

        supportFragmentManager.beginTransaction()
            .replace(R.id.fragment_container, sampleFragment)
            .commit()
    }
}

// SampleFragment.kt
class SampleFragment : Fragment() {

    companion object {
        private const val ARG_MESSAGE = "message"

        fun newInstance(message: String): SampleFragment {
            val fragment = SampleFragment()
            val bundle = Bundle()
            bundle.putString(ARG_MESSAGE, message)
            fragment.arguments = bundle
            return fragment
        }
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view = inflater.inflate(R.layout.fragment_sample, container, false)
        val message = arguments?.getString(ARG_MESSAGE)
        view.textView.text = message
        return view
    }
}

class LifecycleFragment : Fragment() {

    override fun onAttach(context: Context) {
        super.onAttach(context)
        Log.d("LifecycleFragment", "onAttach")
    }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        Log.d("LifecycleFragment", "onCreate")
    }

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        Log.d("LifecycleFragment", "onCreateView")
        return inflater.inflate(R.layout.fragment_lifecycle, container, false)
    }

    override fun onStart() {
        super.onStart()
        Log.d("LifecycleFragment", "onStart")
    }

    // 他のライフサイクルメソッドも同様にログを出力
}

class TabActivity : AppCompatActivity() {

    private val viewPager: ViewPager by lazy { findViewById<ViewPager>(R.id.viewPager) }
    private val tabLayout: TabLayout by lazy { findViewById<TabLayout>(R.id.tabLayout) }

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_tab)

        setupViewPager(viewPager)
        tabLayout.setupWithViewPager(viewPager)
    }

    private fun setupViewPager(viewPager: ViewPager) {
        val adapter = ViewPagerAdapter(supportFragmentManager)
        adapter.addFragment(TabFragment1(), "Tab1")
        adapter.addFragment(TabFragment2(), "Tab2")
        viewPager.adapter = adapter
    }
}

class DynamicActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_dynamic)

        val addButton: Button = findViewById(R.id.addButton)
        addButton.setOnClickListener {
            val fragment = DynamicFragment()
            supportFragmentManager.beginTransaction()
                .add(R.id.fragment_container, fragment)
                .commit()
        }
    }
}

class MultipleFragmentsActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_multiple_fragments)

        if (savedInstanceState == null) {
            supportFragmentManager.beginTransaction()
                .add(R.id.fragmentContainer1, FirstFragment())
                .add(R.id.fragmentContainer2, SecondFragment())
                .commit()
        }
    }
}

class SwipeFragmentsActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_swipe_fragments)

        val fragments = listOf(FirstFragment(), SecondFragment(), ThirdFragment())
        val adapter = SwipeFragmentsAdapter(supportFragmentManager, fragments)
        val viewPager: ViewPager = findViewById(R.id.viewPager)
        viewPager.adapter = adapter
    }
}

class StateFragment : Fragment() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        retainInstance = true
    }

    override fun onSaveInstanceState(outState: Bundle) {
        super.onSaveInstanceState(outState)
        outState.putString("key", "value")
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        if (savedInstanceState != null) {
            val value = savedInstanceState.getString("key")
        }
    }
}

class MainActivity : AppCompatActivity() {

    fun addFragment() {
        val transaction = supportFragmentManager.beginTransaction()
        val existingFragment = supportFragmentManager.findFragmentByTag(MyFragment::class.java.simpleName)

        if (existingFragment == null) {
            transaction.add(R.id.container, MyFragment(), MyFragment::class.java.simpleName)
        }

        transaction.commit()
    }
}

class CustomStyleFragment : Fragment() {

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val contextThemeWrapper = ContextThemeWrapper(activity, R.style.CustomFragmentStyle)
        val localInflater = inflater.cloneInContext(contextThemeWrapper)
        return localInflater.inflate(R.layout.fragment_custom_style, container, false)
    }
}

class AnimatedFragment : Fragment() {

    override fun onCreateAnimator(transit: Int, enter: Boolean, nextAnim: Int): Animator {
        return when (nextAnim) {
            R.animator.slide_in_right -> ObjectAnimator.ofFloat(view, "translationX", 500f, 0f)
            R.animator.slide_out_left -> ObjectAnimator.ofFloat(view, "translationX", 0f, -500f)
            else -> super.onCreateAnimator(transit, enter, nextAnim)
        }
    }
}

class TransitionFragment : Fragment() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        sharedElementEnterTransition = TransitionInflater.from(context).inflateTransition(R.transition.move)
        sharedElementReturnTransition = TransitionInflater.from(context).inflateTransition(R.transition.move)
    }
}