I have created my view how I want it to look. It has 1 images, an input box, and a button. I will want to load another activity when the button is clicked. I am confused why there are fragments and activities. I am new to the Android world (coming from iOS).
My understanding is that Activities are similar to ViewControllers, but I am not sure I understand what a fragment is.
Where do I put the event handling?
package com.phppointofsale.phppointofsale;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
public class StoreUrlActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_store_url);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new StoreUrlFragement()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.store_url, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class StoreUrlFragement extends Fragment {
public StoreUrlFragement() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_store_url,
container, false);
return rootView;
}
}
}
Firstly I would recommend reading this Fragments . Pay particular attention to the created fragment section, which includes the fragment life-cycle diagram. Second download and compile this Sample App,the effective navigation app will help you understand how different fragments work in tandem, and even implements a action bar.
To answer your question more or less a fragment can be thought of as a separate class. Once you call upon that particular fragment you can call functions from within that class.
Fragment Case-Switch
This is some sample code to show you what I mean.
public Fragment getItem(int i){
switch (i) {
case 0:
// The first section of the app is the most interesting -- it offers
// a launchpad into the other demonstrations in this example application.
return new LaunchpadSectionFragment();
case 1:
return new BluetoothClass();
default:
// The GPS section of the app .
Fragment fragment = new DummySectionFragment();
Bundle args = new Bundle();
args.putInt(DummySectionFragment.ARG_SECTION_NUMBER, i + 1);
fragment.setArguments(args);
return fragment;
}
}
In this case each fragment for me represented a class, which was implemented in a separate tab and each tab had a separate functionality. One of the key advantages of fragments is you can run separate activities without first letting one activity complete.
Furthermore each fragment is an extension of the java.lang.Object library. So it has all those functions + additional ones. I would read this as well. Lastly it would be a good idea to have separate xml files for each fragment then you can display that separately when a fragment is invoked.
Some more code
Each fragment will/could have this
public void onActivityCreated(Bundle savedInstanceState){
super.onActivityCreated(savedInstanceState);
// Do stuff on creation. This is usually where you add the bulk of your code. Like clickListners
View rootview = inflater.inflate(R.layout.xml_the_fragment_uses container,false);
rootview.findViewById(R.id.your_id).setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
//Do something
}
});
}
public void onStart(){
super.onStart();
Toast.makeText(getActivity(), "Fragment started",Toast.LENGTH_SHORT).show();
}
public void onResume(){
super.onStart();
Toast.makeText(getActivity(), "Fragment Resumed",Toast.LENGTH_SHORT).show();
}
public void onStop(){
super.onStart();
Toast.makeText(getActivity(), "Fragment Stoped",Toast.LENGTH_SHORT).show();
disableBT();
}
Remember these functions are from the fragment life-cycle I mentioned earlier.
Hopefully that gave you some idea on fragments. Also remember to read this as a lot of functionality uses the v7 app compat library. Including the fragment manager.
Related
I am working on a simple android application that has MainActivity with FragmentStatePagerAdapter and some number of fragments side by side. I want to be able to go to the first fragment by pressing home button.
I know my code is pretty bad. Still I hope just a few lines will solve my problem.
Here is my MainActivity
package com.freestylers.druskischool;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.app.FragmentStatePagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.Menu;
import android.view.MenuItem;
public class MainActivity extends FragmentActivity {
ViewPager pager;
FragmentStatePagerAdapter adapter;
* Each page of our pager will display one fragment from this array
* Swiping, to the right will take you to the next page
*/
String[] fragments={
"start",
"mes",
"whatever",
"next",
"name",
"of",
"a",
"fragment",
"more fragments",
"and",
"more",
"fragments"
};
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
pager=(ViewPager)findViewById(R.id.my_pager);
adapter=new FragmentStatePagerAdapter(
//maybe should use normal getFragmentManager()
getSupportFragmentManager()
){
#Override
public int getCount() {
// This makes sure getItem doesn't use a position
// that is out of bounds of our array of fragments
return fragments.length;
}
#Override
public Fragment getItem(int position) {
// Here is where all the magic of the adapter happens
// As you can see, this is really simple.
//(fragments[position]);
if(position==0){
return StartFragment.newInstance();
}
else if(position==1){
return MesFragment.newInstance();
}
else if(position==2){
returnNextFragment.newInstance();
}
//this goes on until position==11
else{return StartFragment.newInstance();}
}
};
//Let the pager know which adapter it is supposed to use
pager.setAdapter(adapter);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
And this is one of my fragments, MesFragment. On the line 19 (commented out by double slash)I just don`t know which command to use to get to my first fragment:
package com.freestylers.druskischool;
import android.annotation.SuppressLint;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
public class MesFragment extends Fragment {
#Override
public boolean onOptionsItemSelected(MenuItem item){
switch(item.getItemId()){
case android.R.id.home:
//(getActivity()).getSupportFragmentManager().??? I don`t know how
to go back to first fragment
return true;
default:
return super.onOptionsItemSelected(item);
}
}
#Override
public View onCreateView(LayoutInflater inflater,
ViewGroup container, Bundle savedInstanceState) {
(getActivity()).getActionBar().setDisplayHomeAsUpEnabled(true);
View view=inflater.inflate(
R.layout.fragment_mes,
container,
false);
return view;
}
// This is the method the pager adapter will use
// to create a new fragment
public static Fragment newInstance(){
MesFragment f=new MesFragment();
return f;
}
}
Thanks
You can set the currently selected item using ViewPager, which is in your activity:
public void switchToMesFragment() {
pager.setCurrentItem(1);
}
To switch from within a fragment, you need to get a reference to your activity and call the switching function, like so:
((MainActivity)getActivity()).switchToMesFragment();
You cannot completely control the Home button key since it is a key that is broadcasted to all active apps on the device. If you want to process the Home button for your app, you may overrride the Activity.onPause() method. Documentation # Pausing an Activity. But still you cannot prevent the user from seeing the Home screen, that's not fair to other apps perhaps. Try this out first...
i'm trying to create a wizard Like Android application, i want to Create an activity and Two dynamic Fragments, the first one will be added when the Activity is created, and the second when the user clicks on a button in the First fragment, right now i can't even add the Fragment to the activity :
Activity onCreate method:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Fragment fr = new FragmentNumber();
getSupportFragmentManager().beginTransaction().add(fr, "number_fragment").commit();
}
this is my activity code, when i run this, the screen is blank.
the R.layout.activity_main refer to an empty Linear Layout, i don't want to add the fragments there because i need them to be dynamic.
Thanks in advance.
EDIT : pasting more files
activity_main.XML
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/fragment_container"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="hello from main"
/>
</FrameLayout>
MaicActivity.java
package com.example.fragmenttraining;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.Toast;
public class MainActivity extends ActionBarActivity{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if(findViewById(android.R.id.content) != null)
{
Log.d("main activity", "content found");
}
FragmentNumber fr = new FragmentNumber();
//getSupportFragmentManager().beginTransaction().add(android.R.id.content, fr, "number_fragment").commit();
getSupportFragmentManager().beginTransaction().replace(android.R.id.content, fr).commit();
}
FragmentNumber numberFragment;
FragmentFacebook facebookFragment;
public void facebookClicked(View view)
{
numberFragment = new FragmentNumber();
numberFragment.facebookClicked(view);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
Now it's working, but the fragment is not replaced, it displays the content of the activity_main + the content of the FragmentNumber fragment even id i replace it ...
Follow these steps:
Create your main (activity layout) file. In it, add a frame layout which will act as a container for your fragments.
Now create your two fragments. This involves creating two xml files that will be inflated inside your fragment's onCreateView method.
One of your fragments (the first one) should have a button that the user will be able to click. That means you must attach an onClick listener to it inside the onCreateView method after finding it by id.
Now create an interface inside your first fragment and add a method in it that your activity should override after implementing the interface.
When the user clicks that button, inside onClick method, you should call the interface method to notify the activity of the click event.
Inside the activity, when the method is called, create a new instance of the second fragment and add it to view by replacing the first one - or it depends on whether you are using two-pane layout in your activity - in that case, you just add the fragment.
Remember to check if your fragment exists first before simply adding one to view.
I hope these steps help you.
Sample Code
public class WizardActivity extends Activity implements SecondFragment.OnButtonClickedListener
{
private FirstFragment firstFragment;
public void onCreate(Bundle saveInstanceState)
{
super.onCreate(saveInstanceState);
setContentView(R.layout.main);
firstFragment = new FirstFragment();
setFragment(firstFragment, "firstFragment");
}
#Override
public void loadSecondFragment()
{
SecondFragment secondFragment = new SecondFragment();
setFragment(secondFragment, "secondFragment");
}
public void setFragment(Fragment frag, String tag)
{
FragmentManager fm = getFragmentManager();
FragmentTransaction ft = fm.beginTransaction();
Fragment fragment = getFragmentManager().findFragmentById(R.id.fragmentContainer);
if(fragment == null)
{
ft.add(R.id.fragmentContainer, frag, tag);
} else {
ft.replace(R.id.fragmentContainer, frag, tag);
}
ft.addToBackStack(null);
ft.commit()
}
}
Now the xml file for main layout.
<LinearLayout ........>
<!--add whatever you need here-->
<FrameLayout
android:id="#+id/fragmentContainer"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
Now let us create one of your fragments - the first one:
FirstFragment.java
public class FirstFragment extends Fragment implements View.OnClickListener
{
private Activity mActivity;
#Override
public void onAttach(Activity act)
{
super.onAttach(act);
this.mActivity = act;
/*Initialize whatever you need here*/
}
#Override
public View onCreateView(LayoutInflator inflator, ViewGroup container, Bundle saveInstanceState)
{
View v = inflator.inflate(R.layout.first_fragment, container, false);
Button button = (Button)v.findViewById(R.id.button);
button.setOnClickListener(this);
}
#Override
public void onClick(View v)
{
((OnButtonClickListener), mActivity).loadSecondFragment();
}
public interface OnButtonClickListener
{
void loadSecondFragment();
}
}
You should be able to just create the second fragment and have it loaded in the activity when a button is clicked.
Good luck.
I am new to programming Android. When I start a new Android Application Project in Eclipse it automatically opens 2 files for me:
MainActivity.java and fragment_main.xml
package com.example.testprogram;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
and
<RelativeLayout 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"
android:paddingBottom="#dimen/activity_vertical_margin"
android:paddingLeft="#dimen/activity_horizontal_margin"
android:paddingRight="#dimen/activity_horizontal_margin"
android:paddingTop="#dimen/activity_vertical_margin"
tools:context="com.example.testprogram.MainActivity$PlaceholderFragment" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/hello_world" />
</RelativeLayout>
I wonder what all this stuff is. The Tutorials I watch always have a different code when they start a new project. For example the .xml file that Eclipse opens for them is named activity_main.xml (unlike mine which is named fragment_main.xml). Also their MainActivity.java has less methods integrated then mine.
Can Someone tell me wether that makes a huge difference and how i can maybe change that.
You are using latest one so it get like this. Don't worry about it.
public class MainActivity extends ActionBarActivity
instead of
public class MainActivity extends Activity
Remove all code in your MainActivity except OnCreate(). Then you follow your tutorial.
You onCreate should be
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
Those are probably old tutorials (on Android platform even after couple of months an tutorial can become old), Android ADT is constantly changing. It now automatically adds an Activity and a Fragment to your project. Instead of just an Activity. You can still use knowledge from those tutorials and fit it into Fragments. Or delete Fragments and use only Activities. But Android is promoting the use of Fragments with Activities, not just mere Activities so you should learn how to use them.
Create New Project Like This:
Start `File->New->Android Application Project->Next->Next->Next->Select-> Empty Activity->Next->Finish
I'm trying to create a small game on Android and have some questions on a specific section of my game. I'm fairly new to android so please excuse if I don't have a full understanding of certain things.
When clicking "play" I'd like to view slide-able menu that makes it able for the user to swipe left and right to choose a level. Overtime I will be adding few more levels but have 2-3 of them now.
What would be the best way to do this? Is it best to implement a fragment for each "level page" or create entirely new activities?
My project is compatible for Android ver. 2.3.3 and above, so it's automatically included the "appcompat_v7" project. (I don't know if that makes a difference).
I've pasted my code below if needed:
package com.example.snake;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
public class SnakeLevelSelectActivity extends FragmentActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_snake_level_select);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.snake_level_select, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_snake_level_select, container, false);
return rootView;
}
}
}
What I intended to do was create several fragment classes and animate between the fragments when the user swipes. I also have issues understanding on how to use several fragments with the "PlaceHolderFragment" class, since the solutions I've found on SO have been different. This is an entirely question, but would be appreciated if it was answered as well.
What would be the best way to do this? Is it best to implement a fragment for each "level page" or create entirely new activities?
This is exactly what a Fragment is for. What you are looking for is already there and named ViewPager. Using ADT and Eclipse you can even create an Activity with this already implemented. Use the "Navigation type" combobox for that purpose:
You can also choose "Action Bar Tabs (with ViewPager)", which will enable Tabs in the ActionBar and make sure that you can switch to different Fragments using both the swipe gesture as well as the tabs.
Android now has this built-in in the SDK.
They call it the Navigation Drawer.
Look up the documentation it contains sample project, it is very easy to implement.
this code is about the default code of MainActivity.java
having problem to understand and also there is a another thing that is the fragmentaion_main.xml file which is likely another buden instead of activity_main.xml why it so ?
package com.example.onehello;
import android.support.v7.app.ActionBarActivity;
import android.support.v7.app.ActionBar;
import android.support.v4.app.Fragment;
import android.os.Bundle;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.os.Build;
public class MainActivity extends ActionBarActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new PlaceholderFragment()).commit();
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
/**
* A placeholder fragment containing a simple view.
*/
public static class PlaceholderFragment extends Fragment {
public PlaceholderFragment() {
}
#Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_main, container,
false);
return rootView;
}
}
}
What is appcompat_v7?
It is the support library added for backwards compatibility. Android has many versions and each new version brings many changes to the API. So, for the older versions of Android to be compatible with the code written for the newer versions, the appcompat_v7 library is helpful.
Why is it being added every time I create a new project?
I assume that you are using Eclipse IDE for the development. Ideally, it would suffice to create one appcompat_v7 folder and make all the projects link to that folder for support library. But, there seems to be some bug in Eclipse. It creates a new appcompat_v7 folder each time a new project is created.
'fragment_main.xml' is like another burden?
Fragment class was introduced in Android API 11. It is useful in creating different layouts for tablets and phones. It is more of a good support to take advantage of the bigger screens on tablets. If you want to develop your application for a smart phone only, you need not even worry about it. So, it's more of an advantage than a burden.
For more reading on fragments, go to http://developer.android.com/reference/android/app/Fragment.html
This appears after installation "Android Support Library":
https://developer.android.com/tools/support-library/features.html