Android 用正确的姿势在 Activity 里面嵌套 Fragment

package com.haocent.android.fragmentsample; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; /** * Activity * * Created by Tnno Wu on 2017/07/18. */ public class MainActivity extends AppCompatActivity { private MainFragment mMainFragment; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); if (savedInstanceState != null) { mMainFragment = (MainFragment) getSupportFragmentManager() .getFragment(savedInstanceState, "MainFragment"); } else { mMainFragment = MainFragment.newInstance(); } getSupportFragmentManager().beginTransaction() .replace(R.id.main, mMainFragment) .commit(); } /** * Store the state when the activity may be recycled. * * @param outState The state data. */ @Override protected void onSaveInstanceState(Bundle outState) { super.onSaveInstanceState(outState); // Store the fragment's states. getSupportFragmentManager().putFragment(outState, "MainFragment", mMainFragment); } }