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      1 /*
      2  * Copyright (C) 2011 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package com.example.android.supportv4.app;
     18 
     19 import android.os.Bundle;
     20 import android.view.LayoutInflater;
     21 import android.view.View;
     22 import android.view.View.OnClickListener;
     23 import android.view.ViewGroup;
     24 import android.widget.Button;
     25 import android.widget.TextView;
     26 
     27 import androidx.core.content.ContextCompat;
     28 import androidx.core.view.ViewCompat;
     29 import androidx.fragment.app.Fragment;
     30 import androidx.fragment.app.FragmentActivity;
     31 import androidx.fragment.app.FragmentManager;
     32 import androidx.fragment.app.FragmentTransaction;
     33 
     34 import com.example.android.supportv4.R;
     35 
     36 public class FragmentStackSupport extends FragmentActivity {
     37     int mStackLevel = 1;
     38 
     39     @Override
     40     protected void onCreate(Bundle savedInstanceState) {
     41         super.onCreate(savedInstanceState);
     42         setContentView(R.layout.fragment_stack);
     43 
     44         // Watch for button clicks.
     45         Button button = findViewById(R.id.new_fragment);
     46         button.setOnClickListener(new OnClickListener() {
     47             @Override
     48             public void onClick(View v) {
     49                 addFragmentToStack();
     50             }
     51         });
     52         button = findViewById(R.id.home);
     53         button.setOnClickListener(new OnClickListener() {
     54             @Override
     55             public void onClick(View v) {
     56                 // If there is a back stack, pop it all.
     57                 FragmentManager fm = getSupportFragmentManager();
     58                 if (fm.getBackStackEntryCount() > 0) {
     59                     fm.popBackStack(fm.getBackStackEntryAt(0).getId(),
     60                             FragmentManager.POP_BACK_STACK_INCLUSIVE);
     61                 }
     62             }
     63         });
     64 
     65         if (savedInstanceState == null) {
     66             // Do first time initialization -- add initial fragment.
     67             Fragment newFragment = CountingFragment.newInstance(mStackLevel);
     68             FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
     69             ft.add(R.id.simple_fragment, newFragment).commit();
     70         } else {
     71             mStackLevel = savedInstanceState.getInt("level");
     72         }
     73     }
     74 
     75     @Override
     76     public void onSaveInstanceState(Bundle outState) {
     77         super.onSaveInstanceState(outState);
     78         outState.putInt("level", mStackLevel);
     79     }
     80 
     81 //BEGIN_INCLUDE(add_stack)
     82     void addFragmentToStack() {
     83         mStackLevel++;
     84 
     85         // Instantiate a new fragment.
     86         Fragment newFragment = CountingFragment.newInstance(mStackLevel);
     87 
     88         // Add the fragment to the activity, pushing this transaction
     89         // on to the back stack.
     90         FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
     91         ft.replace(R.id.simple_fragment, newFragment);
     92         ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN);
     93         ft.addToBackStack(null);
     94         ft.commit();
     95     }
     96 //END_INCLUDE(add_stack)
     97 
     98 //BEGIN_INCLUDE(fragment)
     99     public static class CountingFragment extends Fragment {
    100         int mNum;
    101 
    102         /**
    103          * Create a new instance of CountingFragment, providing "num"
    104          * as an argument.
    105          */
    106         static CountingFragment newInstance(int num) {
    107             CountingFragment f = new CountingFragment();
    108 
    109             // Supply num input as an argument.
    110             Bundle args = new Bundle();
    111             args.putInt("num", num);
    112             f.setArguments(args);
    113 
    114             return f;
    115         }
    116 
    117         /**
    118          * When creating, retrieve this instance's number from its arguments.
    119          */
    120         @Override
    121         public void onCreate(Bundle savedInstanceState) {
    122             super.onCreate(savedInstanceState);
    123             mNum = getArguments() != null ? getArguments().getInt("num") : 1;
    124         }
    125 
    126         /**
    127          * The Fragment's UI is just a simple text view showing its
    128          * instance number.
    129          */
    130         @Override
    131         public View onCreateView(LayoutInflater inflater, ViewGroup container,
    132                 Bundle savedInstanceState) {
    133             View v = inflater.inflate(R.layout.hello_world, container, false);
    134             View tv = v.findViewById(R.id.text);
    135             ((TextView) tv).setText("Fragment #" + mNum);
    136             ViewCompat.setBackground(tv,
    137                     ContextCompat.getDrawable(getContext(), android.R.drawable.gallery_thumb));
    138             return v;
    139         }
    140     }
    141 //END_INCLUDE(fragment)
    142 }
    143