Update fragment samples to show back stacks and layout.

Change-Id: I016f87dc3b7433d0600a9a9308f666a36c5a98ca

samples/ApiDemos/src/com/example/android/apis/app/FragmentLayout.java

@@ -0,0 +1,66 @@
+/*
+ * Copyright (C) 2010 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.example.android.apis.app;
+
+import com.example.android.apis.R;
+
+import android.app.Activity;
+import android.app.Fragment;
+import android.app.FragmentTransaction;
+import android.os.Bundle;
+import android.view.LayoutInflater;
+import android.view.View;
+import android.view.ViewGroup;
+import android.view.View.OnClickListener;
+import android.widget.Button;
+import android.widget.TextView;
+
+public class FragmentLayout extends Activity {
+    View mFirstFragmentView;
+    View mSecondFragmentView;
+    
+    @Override
+    protected void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.fragment_layout);
+        mFirstFragmentView = findViewById(R.id.fragment1);
+        mSecondFragmentView = findViewById(R.id.fragment2);
+    }
+    
+    static class FirstFragment extends Fragment {
+        // Explicit constructor needed for inflation.
+        public FirstFragment() {
+        }
+        
+        public View onCreateView(LayoutInflater inflater, ViewGroup container) {
+            return inflater.inflate(R.layout.hello_world, container, false);
+        }
+    }
+    
+    static class SecondFragment extends Fragment {
+        // Explicit constructor needed for inflation.
+        public SecondFragment() {
+        }
+        
+        public View onCreateView(LayoutInflater inflater, ViewGroup container) {
+            View v = inflater.inflate(R.layout.hello_world, container, false);
+            View tv = v.findViewById(R.id.text);
+            ((TextView)tv).setText("Second Hello World!");
+            return v;
+        }
+    }
+}

samples/ApiDemos/src/com/example/android/apis/app/FragmentStack.java

@@ -29,49 +29,49 @@ import android.view.View.OnClickListener;
 import android.widget.Button;
 import android.widget.TextView;
 
-public class SimpleFragment extends Activity {
-    int mWhichFragment;
-    Fragment mCurFragment;
+public class FragmentStack extends Activity {
+    int mStackLevel;
+    Fragment mLastFragment;
     
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
-        setContentView(R.layout.simple_fragment);
-        switchToFragment(0);
+        setContentView(R.layout.fragment_stack);
+        addFragmentToStack();
         
         // Watch for button clicks.
         Button button = (Button)findViewById(R.id.next);
         button.setOnClickListener(new OnClickListener() {
             public void onClick(View v) {
-                switchToFragment(mWhichFragment == 0 ? 1 : 0);
+                addFragmentToStack();
             }
         });
     }
     
-    void switchToFragment(int which) {
-        mWhichFragment = which;
-        Fragment newFragment = which == 0
-                ? new FirstFragment() : new SecondFragment();
+    void addFragmentToStack() {
+        mStackLevel++;
+        Fragment newFragment = new CountingFragment(mStackLevel);
         FragmentTransaction ft = openFragmentTransaction();
-        if (mCurFragment != null) {
-            ft.remove(mCurFragment);
+        if (mLastFragment != null) {
+            ft.remove(mLastFragment);
         }
         ft.add(newFragment, R.id.simple_fragment);
-        mCurFragment = newFragment;
+        mLastFragment = newFragment;
+        ft.addToBackStack();
         ft.commit();
     }
     
-    class FirstFragment extends Fragment {
-        public View onCreateView(LayoutInflater inflater, ViewGroup container) {
-            return inflater.inflate(R.layout.hello_world, container, false);
+    class CountingFragment extends Fragment {
+        final int mNum;
+        
+        public CountingFragment(int num) {
+            mNum = num;
         }
-    }
-    
-    class SecondFragment extends Fragment {
+        
         public View onCreateView(LayoutInflater inflater, ViewGroup container) {
             View v = inflater.inflate(R.layout.hello_world, container, false);
             View tv = v.findViewById(R.id.text);
-            ((TextView)tv).setText("Second Hello World!");
+            ((TextView)tv).setText("Fragment #" + mNum);
             return v;
         }
     }