Fragment 基礎

package com.advanced_android.fragmenttransactionsample;

import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.View;

public class MainActivity extends AppCompatActivity {

    private static final String FRAGMENT_TAG = "FRAGMENT_TAG";
    private static final String KEY_NUMBER = "KEY_NUMBER";
    private int mNumber = 0;
    private FragmentManager.OnBackStackChangedListener mListener = new FragmentManager.OnBackStackChangedListener() {
        @Override
        public void onBackStackChanged() {
            FragmentManager fragmentManager = getSupportFragmentManager();
            int count = 0;
            for (Fragment f : fragmentManager.getFragments()) {
                if (f != null) {
                    count++;
                }
            }
            mNumber = count;
            Log.d("MainActivity", "onBackStackChanged mNumber=" + mNumber);
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        findViewById(R.id.add_button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                FragmentManager fragmentManager = getSupportFragmentManager();
                fragmentManager.beginTransaction()
                    .add(R.id.fragment_container, MyFragment.getInstance(mNumber))
                    .addToBackStack(null)
                    .commit();
            }
        });
        findViewById(R.id.remove_button).setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (mNumber == 0) {
                    return;
                }
                FragmentManager fragmentManager = getSupportFragmentManager();
                fragmentManager.popBackStack();
            }
        });

        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.addOnBackStackChangedListener(mListener);
        Fragment fragment = fragmentManager.findFragmentByTag(FRAGMENT_TAG);
        Log.d("MainActivity", "onCreate fragment=" + fragment + ", mNumber=" + mNumber);
        if (savedInstanceState == null) {
            fragmentManager.beginTransaction()
                .add(R.id.fragment_container, MyFragment.getInstance(mNumber), FRAGMENT_TAG)
                .addToBackStack(null)
                .commit();
        }
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        FragmentManager fragmentManager = getSupportFragmentManager();
        fragmentManager.removeOnBackStackChangedListener(mListener);
    }

    @Override
    public void onSaveInstanceState(Bundle outState) {
        super.onSaveInstanceState(outState);
        outState.putInt(KEY_NUMBER, mNumber);
    }

    @Override
    protected void onRestoreInstanceState(Bundle savedInstanceState) {
        super.onRestoreInstanceState(savedInstanceState);
        mNumber = savedInstanceState.getInt(KEY_NUMBER);
    }
}

package com.advanced_android.fragmenttransactionsample;


import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.TextView;


public class MyFragment extends Fragment {

    private static final String ARG_NO = "ARG_NO";

    public MyFragment() {
    }

    public static MyFragment getInstance(int no) {
        MyFragment fragment = new MyFragment();
        Bundle args = new Bundle();
        args.putInt(ARG_NO, no);
        fragment.setArguments(args);
        return fragment;
    }
    
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        return inflater.inflate(R.layout.fragment_my, container, false);
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        int no = getArguments().getInt(ARG_NO, 0);
        String text = "" + no + "番目のFragment";
        Log.d("MyFragment", "onCreate " + text);
    }

    @Override
    public void onViewCreated(View view, Bundle savedInstanceState) {
        super.onViewCreated(view, savedInstanceState);
        TextView textView = (TextView) view.findViewById(R.id.text);
        int no = getArguments().getInt(ARG_NO, 0);
        String text = "" + no + "番目のFragment";
        Log.d("MyFragment", "onViewCreated " + text);
        textView.setText(text);
    }
}