I'm new in android programming and I'm making a very simple app.
I only have one text view and one button, and when I click the button I want to show in the text view a value that represents how long the activity was open.
this is my xml file:
<Button
android:id = "#+id/button"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="Button" />
<TextView
android:id="#+id/textView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_above="#+id/button"
android:layout_centerHorizontal="true"
android:text=" " />
</RelativeLayout>
and this is my java file:
package com.diogoc.teste;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class MainActivity extends Activity {
TextView textView;
Button button;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
textView = (TextView) findViewById(R.id.textView);
button = (Button) findViewById(R.id.button);
button.setOnClickListener(Listener);
}
#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;
}
private OnClickListener Listener = new OnClickListener() {
public void onClick(View v) {
//It's here
textView.setText("You take");
}
};
}
Thank you.
Add this member variable to the class:
long startTime;
Add this to your onCreate()-method:
startTime = System.currentTimeMillis();
Add this to your onClick()-method:
long timeElapsedMS = System.currentTimeMillis()-startTime; //gets the time difference in milliseconds
long timeElapsedSeconds = timeElapsedMS/1000;
textView.setText("You took "+timeElapsedSeconds+" seconds");
Something like this in your onCreate will work:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
/* Other stuff omitted */
final long start= System.currentTimeMillis();
final Handler handler = new Handler();
handler.postDelayed(new Runnable(){
#Override
public void run(){
textView.setText(System.currentTimeMillis() - start);
handler.postDelayed(this, 100);
}
}, 100);
}
The code in the run() method will run indefinately every 100 ms, updating the text in your textview with the milliseconds passed since the call to onCreate().
Related
I have just gone through the android "first app" tutorial located Here, and I want to start experimenting on my own with the stuff that tutorial taught me.
What I want to do is take the message the user writes in the first activity, and display it in a TextView element, which i have defined in the XML file for the second activity. How do I edit the properties of a text view using the java code? I have no idea how to edit any of the properties of the element, even though I know its android:id . Can anyone give me any insight into this?
TextView textView = (TextView) findViewById(R.id.id_of_the_textview);
textView.setText(yourNewText);
What I want to do is take the message the user writes in the first activity
I assume you'll use an EditText in your FirstActivity, so you have to get the text from this widget and pass it as an extra in your intent used to switch to the second activity.
In your FirstActivity onCreate method it will look like :
EditText myEditText = (EditText) findViewById(R.id.yourEditTextId);
Intent i = new Intent(this, ToClass.class);
i.putExtra("myText", myEditText.getText().toString());
startActivity(i);
And in your SecondActivity onCreate methode :
Intent intent = getIntent();
String text = intent.getExtras().getString("myText");
TextView myTextView = (TextView) findViewById(R.id.yourTextViewId);
myTextView.setText(text);
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.EditText;
public class MainActivity extends Activity {
Button button1;
String text;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addListenerOnButton();
}
public void addListenerOnButton() {
button1 = (Button) findViewById(R.id.buttoncalculate);
button1.setOnClickListener(new View.OnClickListener() {
public void onClick(View view) {
EditText editText = (EditText)findViewById(R.id.editText1);
String text = editText.getText().toString();
Intent myIntent = new Intent(view.getContext(),Calculated.class);
myIntent.putExtra("mytext",text);
startActivity(myIntent);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.activity_main, menu);
return true;
}
}
Calculated.java
public class Calculated extends Activity {
TextView mTextview;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.calculated);
mTextview = (TextView)findViewById(R.id.textView1);
mTextview.setText(getIntent().getStringExtra("mytext"));
}
calculated.xml
<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"
tools:context=".MainActivity" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_marginTop="42dp"
android:textAppearance="?android:attr/textAppearanceLarge" />
</RelativeLayout>
I have an existing application that I am trying to modify and could really use some help.
It is a chat application. The original flow of the application was as follows:
Launch-> Splash Screen Activity-> MainActivity (extending Actionbar Sherlock)
Once in the main activity the default fragment is the ChatRoomFragment. From there you can select different tabs and interact with the application.
What I would like to change about the flow to is the following:
Launch->Splash Screen Activity-> Terms of Service/Sign -> MainMenu->MainActivity
I have created the mainmenu layout to contain 4 buttons. Join, Search, Profile, Settings
Here is the problem. My Join button works fine, onClick simply triggers the intent to start MainActivity and and the chat room loads. From this screen you can access the different tabs and fragments within the application.
However, I now would like to have the "search" button set to open a dialog. With a editText field and a search button. Upon clicking search it should pass the search string to the PlacesSearchFragment and populate results.
I copied the code from within my application where this search is normally completed (inside the ChatRoomsFragment but it will not work from within my mainMenu Activity.
How do I start the new fragment from the menu activity??
Code Below:
menuActivity.java
package com.peekatucorp.peekatu;
//import android.support.v7.app.ActionBarActivity;
import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.Intent;
import android.content.SharedPreferences;
import android.os.Bundle;
import android.support.v4.app.FragmentTransaction;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import android.widget.Toast;
import com.actionbarsherlock.app.ActionBar;
import com.loopj.android.http.AsyncHttpClient;
import com.loopj.android.http.AsyncHttpResponseHandler;
import com.loopj.android.http.RequestParams;
import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.NodeList;
public class menuActivity extends Activity implements ActionBar.TabListener {
Button b1;
Button b2;
Button b3;
EditText txtsearch;
final private static int DIALOG_LOGIN = 1;
final private static int DIALOG_FORGET = 2;
final private static int DIALOG_SEARCH = 3;
private android.app.FragmentTransaction ft;
#Override
public void onCreate(Bundle savedInstanceState) {
SharedPreferences preferences = this.getSharedPreferences("MyPreferences", MODE_PRIVATE);
SharedPreferences.Editor editor = preferences.edit();
super.onCreate(savedInstanceState);
setContentView(R.layout.mainmenu);
if(preferences.getString("Username", "").length()<=0 || preferences.getString("loggedin_user", "").length()<=0){
showDialog(DIALOG_LOGIN);
}
b1= (Button) this.findViewById(R.id.joinbutton);
b1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
Intent intent = new Intent(menuActivity.this, MainActivity.class);
menuActivity.this.startActivity(intent);
SharedPreferences preferences = getSharedPreferences("MyPreferences", MODE_PRIVATE);
SharedPreferences.Editor editor = preferences.edit();
editor.putString("loadMain", "1");
editor.commit();
}
});
b2= (Button) this.findViewById(R.id.searchbutton);
b2.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
showDialog(DIALOG_SEARCH);
}
}
);
}
#Override
protected Dialog onCreateDialog(int id) {
AlertDialog dialogDetails = null;
switch (id) {
case DIALOG_LOGIN:
if(true){
....some code}
break;
case DIALOG_FORGET:
if(true){
...some code
}
break;
case DIALOG_SEARCH:
if(true){
LayoutInflater inflater = LayoutInflater.from(this);
View dialogview = inflater.inflate(R.layout.menusearch_layout, null);
AlertDialog.Builder dialogbuilder = new AlertDialog.Builder(this);
dialogbuilder.setTitle("Where ya headed?");
dialogbuilder.setView(dialogview);
dialogDetails = dialogbuilder.create();
}
}
return dialogDetails;
}
#Override
protected void onPrepareDialog(int id, Dialog dialog) {
switch (id) {
case DIALOG_LOGIN:
...some code
break;
case DIALOG_SEARCH:
final AlertDialog alertDialog3 = (AlertDialog) dialog;
final Button btnLocalsearch = (Button) alertDialog3
.findViewById(R.id.local_search);
final Button btnSearch = (Button) alertDialog3
.findViewById(R.id.btn_search);
final EditText txtsearch = (EditText) alertDialog3
.findViewById(R.id.txtsearch);
btnSearch.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(final View v) {
//showDialog(DIALOG_FORGET);
//alertDialog3.dismiss();
// TODO Auto-generated method stub
menuActivity m = com.peekatucorp.peekatu.menuActivity.this;
final TabInfo tab = com.peekatucorp.peekatu.menuActivity.this.getCurrentTabInfo();
final PlacesSearchFragment fragment = new PlacesSearchFragment().setNAV(m).setSearch(txtsearch.getText().toString(),"1");
// fragment.setText(characters[position]);
// second, you push the fragment. It becomes visible and the up button is
// shown
m.pushFragment(tab, fragment);
}
});
}
mainmenu.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android">
<ImageView
android:layout_width="wrap_content"
android:layout_height="65dp"
android:layout_marginLeft="10dip"
android:src="#drawable/registration_banner3"
android:id="#+id/imageView" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Join Chat"
android:id="#+id/joinbutton"
android:layout_below="#+id/imageView"
android:layout_alignLeft="#+id/imageView"
android:layout_alignStart="#+id/imageView"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Search"
android:id="#+id/searchbutton"
android:layout_below="#+id/joinbutton"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true"
android:layout_marginTop="55dp"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Profile"
android:id="#+id/prfbutton"
android:layout_below="#+id/searchbutton"
android:layout_marginTop="72dp"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_alignLeft="#+id/searchbutton"
android:layout_alignStart="#+id/searchbutton" />
<Button
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Settings"
android:id="#+id/settingsbutton"
android:layout_below="#+id/prfbutton"
android:layout_marginTop="51dp"
android:layout_alignParentRight="true"
android:layout_alignParentEnd="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<LinearLayout android:id="#+id/footer"
android:orientation="horizontal"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:background="#layout/footer_repeat"
android:layout_alignParentBottom="true">
</LinearLayout>
</RelativeLayout>
ChatRoomsFragment.java (WORKING FRAGMENT)
public class ChatRoomsFragment extends SherlockFragment implements OnItemSelectedListener{
String[] items;
List<String> list;
Spinner my_spin;
RadioButton mainRoom;
RadioButton customRoom;
RadioButton GPSRoom;
EditText privateRoom;
EditText GPSsearch;
TextView GPSaddress;
String selected_public;
Context contexxt;
ImageLoader imageLoader;
public AbstractTabStackNavigationActivity navact;
#Override
public View onCreateView(final LayoutInflater inflater, final ViewGroup container, final Bundle savedInstanceState) {
setRetainInstance(true);
final View v = inflater.inflate(R.layout.chatrooms_layout, container, false);
contexxt = v.getContext();
// setRetainInstance(true);
SharedPreferences preferences = v.getContext().getSharedPreferences("MyPreferences", this.getActivity().MODE_PRIVATE);
my_spin=(Spinner)v.findViewById(R.id.spinner1);
my_spin.setOnItemSelectedListener(this);
selected_public = preferences.getString("selected_room", "Adult Lobby");
AsyncHttpClient client = new AsyncHttpClient();
RequestParams params = new RequestParams();
GPSsearch = (EditText)v.findViewById(R.id.cr_gps_search);
GPSaddress = (TextView)v.findViewById(R.id.cr_gps_address);
GPSaddress.setText(preferences.getString("user_location", ""));
Button search_go = (Button)v.findViewById(R.id.cr_go_search);
Button address_go = (Button)v.findViewById(R.id.cr_go_address);
Button changeroom = (Button)v.findViewById(R.id.cr_changeroom);
//Button changeroom2 = (Button)v.findViewById(R.id.cr_changeRoom2);
search_go.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
MainActivity m = (MainActivity)getActivity();
final TabInfo tab = m.getCurrentTabInfo();
final PlacesSearchFragment fragment = new PlacesSearchFragment().setNAV(m).setSearch(GPSsearch.getText().toString(),"1");
// fragment.setText(characters[position]);
// second, you push the fragment. It becomes visible and the up button is
// shown
m.pushFragment(tab, fragment);
}
});
Can someone please explain to me how to get it to load the fragment. Thank you. Let me know if I am leaving out any relevant code. Im getting a null pointer exception as my error.
Well, first of all, here is the code I was talking about in my comment:
btnSearch.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(final View v) {
menuActivity m = dialog.getOwningActivity();
final TabInfo tab = m.getCurrentTabInfo();
final PlacesSearchFragment fragment = new PlacesSearchFragment().setNAV(m).setSearch(txtsearch.getText().toString(),"1");
m.pushFragment(tab, fragment);
...
However, now that I type this up, it doesn't make sense that the NPE was on the call to pushFragment like you said. If the activity outer-class reference was really the null pointer, then it should have crashed a few lines earlier, calling getCurrentTabInfo. Thus I don't think this code change will help. Please take a second look at the stack you are seeing, and tell me what line the NPE is happening on.
I'm trying to build an text view that goes to onClick but its not working they told me to add this code I did it but I'm having a lot of errors in it.
this is my MainActivity.java
package imamalsajadsayings.android.com;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void runNextTask(){
final View addView = getLayoutInflater().inflate(R.layout.addnewtracker, null);
final TrackerInfo newInfo = new TrackerInfo();
//set up for model selection
TextView modelTextview = (TextView)addView.findViewById(R.id.state1);
modelTextview.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
}
});
}
#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;
}
}
and is my textview
<TextView
android:id="#+id/state1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/Tracker_model"
android:clickable="true"
note : I don't have addnewtracker created
errors :
Description Resource Path Location Type
TrackerInfo cannot be resolved to a type MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 20 Java Problem
addnewtracker cannot be resolved or is not a field MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 19 Java Problem
The method setOnClickListener(View.OnClickListener) in the type View is not applicable for the arguments (new OnClickListener(){}) MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 23 Java Problem
TrackerInfo cannot be resolved to a type MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 20 Java Problem
The method onClick(View) of type new OnClickListener(){} must override or implement a supertype method MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 25 Java Problem
OnClickListener cannot be resolved to a type MainActivity.java /ImamAlsajadsayings/src/imamalsajadsayings/android/com line 23 Java Problem
add to activity:
public void modelTextViewClick(View v) {
//do something on click
}
and to layout:
<TextView android:id="#+id/state1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/Tracker_model"
android:clickable="true"
android:onClick="modelTextViewClick"/>
and remove your on click listener.
Change below code to your XML file
<TextView android:id="#+id/state1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/Tracker_model"
android:clickable="true"
android:onClick="runNextTask"/>
and just modify your java file as follow.
public void runNextTask(View v){
final View addView = getLayoutInflater().inflate(R.layout.addnewtracker, null);
final TrackerInfo newInfo = new TrackerInfo();
//set up for model selection
TextView modelTextview = (TextView)addView.findViewById(R.id.state1);
modelTextview.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
}
});
you need to import this package to avoid this error
missing this -> import android.view.View.OnClickListener;
Use below piece of code.
package imamalsajadsayings.android.com;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends Activity {
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void runNextTask(){
final View addView = getLayoutInflater().inflate(R.layout.addnewtracker, null);
final TrackerInfo newInfo = new TrackerInfo();
//set up for model selection
TextView modelTextview = (TextView)addView.findViewById(R.id.state1);
}
#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;
}
public void modelTextViewClick(View view)
{
// here view reference is your text view reference.
// put your on click handler code.
}
}
difference between this code and your code is onclick handler. In xml you have already defined a on click handler which you have to use in activity code. Other way set onclick listener handler foe your widget. Your doing both but either one of them is allowed not both for any widget in android.
You haven't call runNextTask from ur onCreate()
u r inflating a layout but didn't add that layout in any layout of ur activity_main layout using addView method
thats why it didn't work
it should be
package imamalsajadsayings.android.com;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.View;
import android.widget.TextView;
import android.view.View.OnClickListener;
public class MainActivity extends Activity {
private LayoutInflater inflater;
private LinearLayout someLayout;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
someLayout = (LinearLayout) findViewById(R.id.some_layout); //layout present in activity_main
inflater = (LayoutInflater)getSystemService(LAYOUT_INFLATER_SERVICE);
runNextTask();
}
public void runNextTask(){
LinearLayout mInflatedLayout = (LinearLayout) inflater.inflate(R.layout.addnewtracker, null);
final TrackerInfo newInfo = new TrackerInfo();
//set up for model selection
TextView modelTextview = (TextView)mInflatedLayout.findViewById(R.id.state1);
someLayout.addView(mInflatedLayout);
modelTextview.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
}
});
}
#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;
}
}
Assuming u r using LinearLayout in ur activity_main layout
i have checked everything in this but still i am getting a null pointer exception . whenever i am trying to change the properties of button in java file, app stop working and logcat showing null pointer exception. plzz help me out
here is my code
package com.example.rapid_finger;
import java.util.Random;
import android.annotation.SuppressLint;
import android.annotation.TargetApi;
import android.app.Activity;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.app.NavUtils;
import android.view.Menu;
import android.view.MenuItem;
import android.widget.Button;
public class PlayScreen extends Activity {
#SuppressLint("NewApi")
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Random rand = new Random();
int data = rand.nextInt(99);
String str = Integer.toString(data);
Button b = (Button) findViewById(R.id.b1);
b.setText(str);
setContentView(R.layout.activity_play_screen);
// Show the Up button in the action bar.
setupActionBar();
}
/**
* Set up the {#link android.app.ActionBar}, if the API is available.
*/
#TargetApi(Build.VERSION_CODES.HONEYCOMB)
private void setupActionBar() {
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
getActionBar().setDisplayHomeAsUpEnabled(true);
}
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.play_screen, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
switch (item.getItemId()) {
case android.R.id.home:
// This ID represents the Home or Up button. In the case of this
// activity, the Up button is shown. Use NavUtils to allow users
// to navigate up one level in the application structure. For
// more details, see the Navigation pattern on Android Design:
//
// http://developer.android.com/design/patterns/navigation.html#up- vs-back
//
NavUtils.navigateUpFromSameTask(this);
return true;
}
return super.onOptionsItemSelected(item);
}
}
and here is my xml file
<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=".PlayScreen" >
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="#string/scores" />
<Button
android:id="#+id/b1"
android:background="#drawable/back"
android:layout_width="wrap_content"
android:layout_height="wrap_content"/>
</RelativeLayout>
You did findViewById before you setContentView.
setContentView should come first
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_play_screen);
Random rand = new Random();
int data = rand.nextInt(99);
String str = Integer.toString(data);
Button b = (Button) findViewById(R.id.b1);
b.setText(str);
// Show the Up button in the action bar.
setupActionBar();
}
put setContentView(R.layout.activity_play_screen); after super.onCreate(savedInstanceState);
// replace this code
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_play_screen);
Random rand = new Random();
int data = rand.nextInt(99);
String str = Integer.toString(data);
Button b = (Button) findViewById(R.id.b1);
b.setText(str);
// Show the Up button in the action bar.
setupActionBar();
}
I have a basic android app set up with a scroll view and text added to it dynamically.
I want it to scroll to the bottom when text is added (which already happens) but I only want it to scroll to the bottom if you are already at the bottom, so if you're reading something it doesn't just scroll.
Here's what I have so far.
private void AddText(final String msg){
this.runOnUiThread(new Runnable() {
public void run() {
TextView log = (TextView) findViewById(R.id.chatlog);
if(log.getText().equals("Loading...")){
log.setText(msg);
}else{
ScrollView scroller = (ScrollView) findViewById(R.id.scroll_container);
//set current scroll position
int scroll_pos = scroller.getScrollY();
//scroll to bottom
scroller.fullScroll(ScrollView.FOCUS_DOWN);
//set bottom position
int scroll_bot = scroller.getScrollY();
//add the text
log.append("\r\n" + msg);
//if you weren't at the bottom
//scroll back to where you were.
//This isn't working, scroll bot is the same
//as scroll pos.
if(scroll_pos != scroll_bot){
scroller.scrollTo(0, scroll_pos);
}
//System.out.println("Pos: " + scroll_pos);
//System.out.println("Bot: " + scroll_bot);
}
}
});
}
The best solution I found so far is to use scrollView.post() method with a runnable that will be invoked after text change:
final ScrollView scrollView = (ScrollView) findViewById(R.id.consoleTab);
TextView textView = (TextView) findViewById(R.id.consoleView);
boolean autoScroll = (textView.getBottom() - (scrollView.getHeight() + scrollView.getScrollY())) <= 0;
textView.setText(state.getConsole().getText());
if (autoScroll) {
scrollView.post(new Runnable() {
public void run() {
scrollView.fullScroll(ScrollView.FOCUS_DOWN);
}
});
}
Here is a working example I got running in the emulator and on my galaxy s.
Basically there are two buttons to add text to the bottom text view, depending on your devices size only the second of these should be usable to see the autoscrolling. The textview being edited uses the ontextchangedlistener to check the scroll position before its text is changed and then to call a delayed (so the screen can update with the additional text) autoscroll where appropriate, after the text has changed.
The layout xml is as follows:
<ScrollView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/scrollmain">
<RelativeLayout
android:id="#+id/mainRelative"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<TextView
android:id="#+id/titleText"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Welcome to the scrolling test application!" />
<Button
android:id="#+id/firstTextAddButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/titleText"
android:text="Click me to add text to the textview below without scrolling"/>
<Button
android:id="#+id/secondTextAddButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="#+id/firstTextAddButton"
android:layout_marginTop="380dp"
android:text="Click me to add text to the textview below and scroll (if you are currently scrolled all the way to the bottom)"/>
<TextView
android:id="#+id/textToEdit"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/secondTextAddButton"
android:textSize="18sp"
android:text="Some text to get us started."/>
/>
</RelativeLayout>
</ScrollView>
And the code for the activity is as follows:
package code.example.scrollingontextchange;
import android.os.Bundle;
import android.os.Handler;
import android.app.Activity;
import android.text.Editable;
import android.text.TextWatcher;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RelativeLayout;
import android.widget.ScrollView;
import android.widget.TextView;
public class MainActivity extends Activity {
private int scroll_pos;
private int maxScrollPosition;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
TextView tv = (TextView)findViewById(R.id.textToEdit);
tv.addTextChangedListener(new TextWatcher(){
#Override
public void afterTextChanged(Editable s) {
if(scroll_pos == maxScrollPosition)
{
Handler h = new android.os.Handler()
{
#Override
public void handleMessage(android.os.Message msg)
{
switch(msg.what)
{
case 0 :
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
ScrollView scrll = (ScrollView)findViewById(R.id.scrollmain);
scrll.fullScroll(ScrollView.FOCUS_DOWN);
break;
default :
break;
}
}
};
h.sendEmptyMessage(0);
}
}
#Override
public void beforeTextChanged(CharSequence s, int start, int count,
int after) {
ScrollView scrll = (ScrollView)findViewById(R.id.scrollmain);
RelativeLayout rl = (RelativeLayout)findViewById(R.id.mainRelative);
scroll_pos = scrll.getScrollY();
maxScrollPosition = rl.getHeight() - scrll.getHeight();
}
#Override
public void onTextChanged(CharSequence s, int start, int before,
int count) {
// TODO Auto-generated method stub
}
});
OnClickListener addTextOnClick = new OnClickListener() {
#Override
public void onClick(View v) {
TextView tv = (TextView)findViewById(R.id.textToEdit);
tv.setText(tv.getText() + "\nA long time ago, in a galaxy s far far away............");
}
};
Button b = (Button)findViewById(R.id.firstTextAddButton);
b.setOnClickListener(addTextOnClick);
Button b2 = (Button)findViewById(R.id.secondTextAddButton);
b2.setOnClickListener(addTextOnClick);
}
#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;
}
}
Hope this helps.
Don't ask me why, but setting your TextView's gravity to bottom it does exactly what you want.