Develop Reference

Problems with creating a new/next Android activity

I just wanted to click on a button in the MainActivity. After I clicked on this button a new activity appears. In this activity is also a button and when I click on this button a text appears. My Problem now is, that the text doesn't appear, when I click on the button. My code for clicking on a button so that a text appears is actually working. But not if I use it in a new Activity/Layout/ page. So there must be s.th. wrong with the Connection between the first and the second activity?!
MainActivity.java:
package com.example.xxx;
import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
#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 page2 (View view){
setContentView(R.layout.pagetwo);
}}
activity_main.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"
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=".MainActivity" >
<Button
android:id="#+id/BtnKlick"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerInParent="true"
android:layout_marginTop="178dp"
android:text="Button"
android:onClick="page2"/>
</RelativeLayout>
Pagetwo.java:
package com.example.xxx;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class Pagetwo extends Activity implements OnClickListener {
public Button btn1;
public TextView tw1;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.pagetwo);
btn1 = (Button) findViewById(R.id.BtnKlick);
tw1 = (TextView) findViewById(R.id.Text);
btn1.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
tw1.setText("Hallo");
}}
pagetwo.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
<Button
android:id="#+id/BtnKlick"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="Klick" />
<TextView
android:id="#+id/Text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="87dp" />
</RelativeLayout>
AndroidManifest.xml:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.xxx"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.xxx.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>

Update
All you seem to be doing is swapping your layouts within PageOne activity.
Change
public void page2 (View view){
setContentView(R.layout.pagetwo);
}
to
public void page2 (View view){
Intent i = new Intent(this, Pagetwo.class);
startActivity(i);
}
This will actually launch your pagetwo activity rather than just swapping layouts within pageone activity
Make that change and all should be good. You will most likely have to add some imports, at least for the intent class
Also Activities must be registered in the manifest. To add the activity to your manifest check the code below
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.xxx.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="Pagetwo"
android:label="#string/app_name" >
</activity>
</application>
Change the label to something more appropriate than app name once you have it working
End update
Try renaming your xml view id's to meet coding standards by using all lower case letters and separating words with underscores. The Android platform may well be getting confused as Text is a reserved word.
so
<TextView
android:id="#+id/Text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="71dp"
android:textSize="70sp" />
becomes
<TextView
android:id="#+id/tv_hallo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_marginTop="71dp"
android:textSize="70sp" />
and your code becomes
...
public TextView tw;
#Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.eclipse);
btn = (Button) findViewById(R.id.BtnKlick);
tw = (TextView) findViewById(R.id.tv_hallo);
btn.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
tw.setText("Hallo");
}
...
Not sure if this is going to have much of an effect but it is just possible android is getting the word Text confused
Also check your logcat output to see if there are any errors.

unfortunately API demo has stopped while running

I have developed an app for page navigation . when a button is clicked the page should navigate to the second page. when i run the project and opened my app its showing unfortunately API demo has stopped. I have posted the entire code of my app . PLS HELP ME OUT...
//MAIN ACTIVITY
<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=".MainActivity" >
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_below="#+id/textView1"
android:layout_marginLeft="73dp"
android:layout_marginTop="14dp"
android:text="Click" />
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignLeft="#+id/button1"
android:layout_alignParentTop="true"
android:layout_marginLeft="14dp"
android:layout_marginTop="34dp"
android:text="Main Activity" />
</RelativeLayout>
//SECONDSCREEN ACTIVITY
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Sceond Screen Activity"
tools:context=".SecondScreenActivity"/>
</LinearLayout>
//JAVA CODE FOR MAIN ACTIVITY
package com.example.navigate;
import android.os.Bundle;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
public class MainActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
addButtonOnClickEventListener();
}
public void addButtonOnClickEventListener()
{
Button button = (Button)findViewById(R.id.button1);
final Context context = this;
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
Intent intent = new Intent(context,SecondScreenActivity.class);
startActivity(intent);
}
});
}
#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;
}
}
// JAVA CODE FOR SECOND SCREEN ACTIVITY
package com.example.navigate;
import android.app.Activity;
public class SecondScreenActivity extends Activity {
}
// MANIFEST FILE
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.navigate"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.navigate.SecondScreenActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name = "android.intent.action.MAIN"/>
<category android:name = "android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
</application>
</manifest>

First problem MainActivity is your launcher page here but you define the secondactivity as luncher in manifest.change it first.
Add an oncreate() to secondactivity otherwise there is nothing to show when the button click.
Third change your MainActivity Context to activity which is MainActivity.this not local
Other things are fine , and hope you understand your small problems..
Change your manifest to something like this:
// MANIFEST FILE
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="18" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.navigate.MainActivity"
android:label="#string/app_name" >
<intent-filter>
<action android:name = "android.intent.action.MAIN"/>
<category android:name = "android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<activity android:name = ".SecondScreenActivity" />
</application>
And in your SecondScreenActivity add an oncreate method with the contet view like:
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.secondactivity_layout);
}
And also in your mainactivity change the context to MainActivity.this . Here you define the context inside onclicklistener which links to your local method not the class.

Implementing a custom indicator with ViewPageIndicator - How can I do it to a gallery?

I'm working on a project and I managed to get to the point where I can show my images in a gallery sort of style using PagerAdapter. Now what I want to do is add an indicator to which image is on the screen and I figure that VPI could help me out - the problem is that I'm really new to code and don't know how to implement it, could someone help?
Here's a gif of what I want to achieve - the green line indicator: http://imgur.com/GgYgY8I
I made a simpler version of my project to fit in this post, here it is:
ImageAdapter.java
package com.exp.viewpagersstest1;
import android.content.Context;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;
public class ImageAdapter extends PagerAdapter {
Context ssContext;
private int[] ssImages = new int[] { R.drawable.splash1,R.drawable.splash2, R.drawable.splash3 };
ImageAdapter(Context ssContext) {
this.ssContext = ssContext;
}
#Override
public int getCount() {
return ssImages.length;
}
#Override
public boolean isViewFromObject(View ssView, Object ssObject) {
return ssView == ((ImageView) ssObject);
}
#Override
public Object instantiateItem(ViewGroup ssContainer, int ssPosition) {
ImageView ssImageView = new ImageView(ssContext);
ssImageView.setScaleType(ImageView.ScaleType.FIT_XY);
ssImageView.setImageResource(ssImages[ssPosition]);
((ViewPager) ssContainer).addView(ssImageView, 0);
return ssImageView;
}
#Override
public void destroyItem(ViewGroup ssContainer, int ssPosition,
Object ssObject) {
((ViewPager) ssContainer).removeView((ImageView) ssObject);
}
}
SSTest.java
package com.exp.viewpagersstest1;
import android.app.Activity;
import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.view.Menu;
public class SSTest extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_sstest);
ViewPager ssViewPager = (ViewPager) findViewById(R.id.ss_view_pager);
ImageAdapter ssAdapter = new ImageAdapter(this);
ssViewPager.setAdapter(ssAdapter);
}
#Override
public boolean onCreateOptionsMenu(Menu menu){
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.sstest, menu);
return true;
}
activity_sstest.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=".SSTest" >
<android.support.v4.view.ViewPager
android:id="#+id/ss_view_pager"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:adjustViewBounds="true" />
</RelativeLayout>
ViewPagerSSTest1 Manifest:
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.exp.viewpagersstest1"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.exp.viewpagersstest1.SSTest"
android:label="#string/app_name"
android:theme="#style/Theme.Sherlock.NoActionBar"
>
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
Thanks in advance to anyone who replies.

Was much more simple than I expected, just needed to add the following to my xml:
<com.viewpagerindicator.UnderlinePageIndicator
android:id="#+id/pageIndic"
android:layout_height="3dp"
android:layout_width="fill_parent"
android:layout_alignParentBottom="true"
app:selectedColor="#ef4154"/>
And the following to the oncreate under the java file:
UnderlinePageIndicator pageIndicator = (UnderlinePageIndicator) findViewById(R.id.pageIndic);
pageIndicator.setViewPager(ssViewPager);

Android - Popup dialog on home/native screens

edit: The problem was trying to display the dialog and finish() the activity the next line, so there was no view for the dialog to show! Would be easier if I could just set home-screen as the context for the dialog.
Newbie here. I know this question has been asked for many times, but there's no full picture on the solution so far. I first started to run some code without GUI, which is successful by simply setting the theme. Now, I want to add dialog to display error from the code, but I cannot get it to show!
<activity android:name="PopupActivity"
android:launchMode="singleInstance" android:excludeFromRecents="true"
android:taskAffinity="" android:theme="#android:style/Theme.Dialog" />
So I created an empty view with wrap_content as width and height, but I'm not sure what view element I should use for the AlertDialog object in the activity. I have tested all my code in another activity with a view, everything works fine, AlertDialog shows without problem.
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:gravity="center_horizontal">
</LinearLayout>
Is there a simple solution? Or I have to treat the Theme.Dialog view as a normal view and add textview and button to emulate a dialog?
I use AlertDialog.Builder for the dialog creation:
AlertDialog.Builder alertDialogB = new AlertDialog.Builder(cont);
alertDialogB.setTitle(title);
alertDialogB.setMessage(msg);
...
...
IDE: IntelliJ
SDK: 4.1.2

You can create simple dialog with different solutions but I used this for starts with.
Here I am adding list of files with code to clarify your doubts:
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.demo"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="14"
android:targetSdkVersion="17" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.demo.LoginActivity"
android:label="#string/app_name"
android:launchMode="singleInstance">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<activity
android:name="com.demo.HomeActivity"
android:label="#string/title_activity_home"
android:theme="#android:style/Theme.Dialog">
</activity>
</application>
</manifest>
LoginActivity.java
package com.demo;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.util.Log;
import android.view.Menu;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.app.Activity;
public class LoginActivity extends Activity {
Button login_btn;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_login);
login_btn=(Button) findViewById(R.id.btnlogin);
login_btn.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
Intent i=new Intent(getApplicationContext(),HomeActivity.class);
startActivity(i);
}
});
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_login, menu);
return true;
}
}
activity_login.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="#+id/LinearLayout1"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
tools:context=".LoginActivity"
android:layout_gravity="center">
<Button
android:id="#+id/btnlogin"
style="?android:attr/buttonStyleSmall"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Login"/>
</LinearLayout>
And one activity which comes as a alert dialog for Login Activity
HomeActivity.java
package com.demo;
import android.os.Bundle;
import android.app.Activity;
import android.util.Log;
import android.view.Menu;
public class HomeActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_home);
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
getMenuInflater().inflate(R.menu.activity_home, menu);
return true;
}
}
activity_home.xml
<LinearLayout 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=".HomeActivity"
android:orientation="vertical">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="#string/hello_world" />
<EditText
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</LinearLayout>

Not sure I got your question right, but you use an activity for the AlertDialog.Builder(getActivity);
And then just Dialog dialog = builder.create();
dialog.show();

I can't get android jsoup to work

Hi i need help with a tutorial i tried from ( http://xjaphx.wordpress.com/2012/02/04/android-xml-adventure-parsing-html-using-jsoup/ ). It's about jsoup but i can't get it to work i only get a lott of errors and stuff.
Here is my code:
package com.sigustgebran.appsl;
import android.os.Bundle;
import org.jsoup.Jsoup;
import org.jsoup.nodes.Document;
import org.jsoup.select.Elements;
import android.app.Activity;
import android.view.Menu;
import android.widget.TextView;
public class MainAct extends Activity {
//blog url
static final String BLOG_URL = "http://xjaphx.wordpress.com/";
#Override
protected void onCreate(Bundle savedInstanceState) {
//set layout view
super.onCreate(savedInstanceState);
setContentView(R.layout.act_main);
//process
try {
((TextView)findViewById(R.id.tvDisplay)).setText(getBlogStats());
} catch (Exception ex) {
((TextView)findViewById(R.id.tvDisplay)).setText("Error");
}
}
protected String getBlogStats() throws Exception {
String result = "";
//get html document structure
Document document = Jsoup.connect(BLOG_URL).get();
//select path
Elements nodeBlogStats = document.select("div#blog-stats ul li");
//check results
if(nodeBlogStats.size() > 0) {
//get value
result = nodeBlogStats.get(0).text();
}
//return
return result;
}
#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;
}
}
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:orientation="vertical"
>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textSize="30sp"
android:layout_gravity="center"
android:id="#+id/tvDisplay"
/>
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.sigustgebran.appsl"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="17" />
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.sigustgebran.appsl.MainAct"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
</application>
</manifest>
I would be really glad if anyone could help me. Thanks

I got it to work now. I had added the jsoup library in "External jars" as he said in the tutorial, but when I deleted it and just copied it in the "libs" map instead it worked.

you have to implement AsyncTask. I think this will help you