任务目标
实现针对Tablets平板设备的大屏适配，一个屏幕下显示更多信息。实现方式为Fragments。
项目管理
项目需要创建以上文件，包括创建两个Activities，分别是创建工程时自动创建的MainActivity和手动创建的DetailActivity；以及一个Fragment需要手动创建，为WorkoutDetailFragment（Fragment的创建方式如下如）；以及两个Java Class文件，分别是Workout和WorkoutListFragment。另外，需要在res文件夹下手动创建layout-large文件夹，用来适配Tablet的Layout文件；在该文件夹下手动创建activity_main.xml即可。
界面编辑
<!-- activity_main.xml -->
<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.LinearLayoutCompat
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<fragment
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/list_fragment"
android:name="com.example.fragment.WorkoutListFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
</androidx.appcompat.widget.LinearLayoutCompat><!-- activity_detail.xml -->
<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.LinearLayoutCompat
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".DetailActivity">
<androidx.fragment.app.FragmentContainerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/fragment_workout"
android:name="com.example.fragment.WorkoutDetailFragment"
/>
</androidx.appcompat.widget.LinearLayoutCompat><!-- fragment_workout_detail.xml -->
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent">
<!-- TODO: Update blank fragment layout -->
<TextView
android:id="@+id/Title_View"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="42dp"
android:textSize="34dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/Description_View"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginTop="19dp"
android:text="26dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/Title_View" />
</androidx.constraintlayout.widget.ConstraintLayout><!-- layout-large/activity_main.xml -->
<?xml version="1.0" encoding="utf-8"?>
<androidx.appcompat.widget.LinearLayoutCompat
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="horizontal">
<fragment
xmlns:android="http://schemas.android.com/apk/res/android"
android:id="@+id/list_frag"
android:name="com.example.fragment.WorkoutListFragment"
android:layout_weight="2"
<!-- 这个fragment在屏幕上占的比例2:3 -->
android:layout_width="0dp"
android:layout_height="match_parent"
/>
<FrameLayout
android:id="@+id/fragment_container"
android:name="com.example.fragment.WorkoutDetailFragment"
android:layout_weight="3"
<!-- 这个fragment在屏幕上占的比例2:3 -->
android:layout_width="0dp"
android:layout_height="match_parent"
/>
</androidx.appcompat.widget.LinearLayoutCompat>Java 逻辑编辑
//MainActivity.java
public class MainActivity extends AppCompatActivity implements WorkoutListFragment.Listener{
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
@Override
public void itemClicked(long id) {
View fragmentContainer = findViewById(R.id.fragment_container);
if(fragmentContainer != null) {
//fragmentContainer是为了适配fragment的容器
WorkoutDetailFragment details = new WorkoutDetailFragment();
FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
details.setWorkoutId((int)id);//?
ft.replace(R.id.fragment_container, details);
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE);
ft.addToBackStack(null);
ft.commit();
}
else {
//如果是手机的话，正常情况下就只有这三句话
Intent intent = new Intent(this, DetailActivity.class);
intent.putExtra(DetailActivity.EXTRA_WORKOUT_ID, (int) id);
startActivity(intent);
}
}
}//DetailActivity.java
public class DetailActivity extends AppCompatActivity {
public static final String EXTRA_WORKOUT_ID = "id";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_detail);
WorkoutDetailFragment frag = (WorkoutDetailFragment) getSupportFragmentManager().findFragmentById(R.id.fragment_workout);
int workoutID = (int) getIntent().getExtras().get(EXTRA_WORKOUT_ID);
frag.setWorkoutId(workoutID);
}
}//Detail.java
public class Workout {
private String name;
private String description;
public static final Workout[] workouts = {
new Workout("Title 1", "Description 1"),
new Workout("Title 2", "Description 2"),
new Workout("Title 3", "Description 3"),
new Workout("Title 4", "Description 4")
};
private Workout(String name, String description){
this.name = name;
this.description = description;
}
public String getDescription(){
return description;
}
public String getName(){
return name;
}
public String toString()
{
return this.name;
}
}//WorkoutDetailFragment.java
public class WorkoutDetailFragment extends Fragment {
private int workoutId;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_workout_detail, container, false);
}
@Override
public void onStart() {
super.onStart();
View view = getView();
if(view!=null)
{
TextView title = view.findViewById(R.id.Title_View);
Workout workout = Workout.workouts[workoutId];
title.setText(workout.getName());
TextView description= view.findViewById(R.id.Description_View);
description.setText(workout.getDescription());
}
}
public void setWorkoutId(int i) {
this.workoutId = i;
}
}//WorkoutListFragment.java
public class WorkoutListFragment extends ListFragment {
static interface Listener {
void itemClicked(long id);
}
private Listener listener;
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
String[] names = new String[Workout.workouts.length];
for(int i = 0; i < names.length; i++) {
names[i] = Workout.workouts[i].getName();
}
ArrayAdapter<String> adapter = new ArrayAdapter<>(inflater.getContext(), android.R.layout.simple_list_item_1, names);
setListAdapter(adapter);
return super.onCreateView(inflater, container, savedInstanceState);
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
this.listener = (Listener) context;
}
@Override
public void onListItemClick(ListView listView, View itemView, int position, long id) {
if(listener != null) {
listener.itemClicked(id);
}
}
}Kotlin 逻辑编辑
//MainActivity.kt
class MainActivity : AppCompatActivity(), WorkoutListFragment.Listener {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
}
override fun itemClicked(id: Long) {
val fragmentContainer = findViewById<View>(R.id.fragment_container)
if (fragmentContainer != null) {
val details = WorkoutDetailFragment()
val ft = supportFragmentManager.beginTransaction()
details.setWorkoutId(id.toInt()) //?
ft.replace(R.id.fragment_container, details)
ft.setTransition(FragmentTransaction.TRANSIT_FRAGMENT_FADE)
ft.addToBackStack(null)
ft.commit()
} else {
val intent = Intent(this, DetailActivity::class.java)
intent.putExtra(DetailActivity.EXTRA_WORKOUT_ID, id.toInt())
startActivity(intent)
}
}
}//DetailActivity.kt
class DetailActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_detail)
val frag: WorkoutDetailFragment? =
supportFragmentManager.findFragmentById(R.id.fragment_workout) as WorkoutDetailFragment?
val workoutID = intent.extras!![EXTRA_WORKOUT_ID] as Int
frag?.setWorkoutId(workoutID)
}
companion object {
const val EXTRA_WORKOUT_ID = "id"
}
}//Workout.kt
class Workout private constructor(private val name: String, private val description: String) {
override fun toString(): String {
return name
}
@JvmName("GetDescription")
fun getDescription(): String {
return description
}
@JvmName("GetName")
fun getName(): String {
return name
}
companion object {
val workouts = arrayOf(
Workout("Title 1", "Description 1"),
Workout("Title 2", "Description 2"),
Workout("Title 3", "Description 3"),
Workout("Title 4", "Description 4")
)
}
}//WorkoutDetailFragment.kt
class WorkoutDetailFragment : Fragment() {
private var workoutId = 0
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_workout_detail, container, false)
}
override fun onStart() {
super.onStart()
val view = view
if (view != null) {
val title = view.findViewById<TextView>(R.id.Title_View)
val workout: Workout = Workout.workouts[workoutId]
title.text = workout.getName()
val description = view.findViewById<TextView>(R.id.Description_View)
description.text = workout.getDescription()
}
}
fun setWorkoutId(i: Int) {
workoutId = i
}
}//WorkoutListFragment.kt
class WorkoutListFragment : ListFragment() {
internal interface Listener {
fun itemClicked(id: Long)
}
private var listener: Listener? = null
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val names = arrayOfNulls<String>(Workout.workouts.size)
for (i in names.indices) {
names[i] = Workout.workouts[i].getName()
}
val adapter = ArrayAdapter(inflater.context, R.layout.simple_list_item_1, names)
listAdapter = adapter
return super.onCreateView(inflater, container, savedInstanceState)
}
override fun onAttach(context: Context) {
super.onAttach(context)
listener = context as Listener
}
override fun onListItemClick(listView: ListView, itemView: View, position: Int, id: Long) {
if (listener != null) {
listener!!.itemClicked(id)
}
}
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