Develop Reference

listView doesn't appear at all. android

listView doesn't appear at all (the activity is white with few things I added (buttons)) and I don't know if its important but this is not my main activity.
edit: I added xml for main activity and items
public class CarsMenu extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_cars_menu);
runListView();
clickFun();
}
private void clickFun() {
ListView list = (ListView) findViewById(R.id.MlistView);
list.setOnItemClickListener(new AdapterView.OnItemClickListener() {
#Override
public void onItemClick(AdapterView<?> parent, View viewClicked, int position, long id) {
TextView textView = (TextView) viewClicked;
Toast.makeText(getApplicationContext(), "clicked", Toast.LENGTH_SHORT).show();
}
});
}
private void runListView(){
String[] getCars = {"blue", "green", "purple", "red"};
ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, R.layout.items, getCars);
ListView list = (ListView) findViewById(R.id.MlistView);
list.setAdapter(adapter);
}
}
activity xml
activity 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="${packageName}.${activityClass}" >
<Button
android:id="#+id/button1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentLeft="true"
android:layout_alignParentTop="true"
android:onClick="btnCarClick"
android:text="Refresh" />
<ListView
android:id="#+id/MlistView"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_below="#+id/button1"
android:layout_centerHorizontal="true" >
</ListView>
</RelativeLayout>
items xml
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent" >
</TextView>
android manifest
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.http"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="19" />
<application
android:allowBackup="true"
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="com.example.http.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="com.example.http.Exception_Error"
android:configChanges="orientation|keyboardHidden|screenSize"
android:label="#string/title_activity_exception__error"
android:theme="#style/FullscreenTheme" >
</activity>
<activity
android:name="com.example.http.Menu_Activity"
android:label="#string/title_activity_menu_" >
</activity>
<activity
android:name="com.example.http.Dev"
android:label="#string/title_activity_dev" >
</activity>
<activity
android:name="com.example.http.AllCars"
android:label="#string/title_activity_all_cars" >
</activity>
<activity
android:name="com.example.http.Cars"
android:label="#string/title_activity_cars" >
</activity>
<activity
android:name="com.example.http.CarsMenu"
android:label="#string/title_activity_cars_menu" >
</activity>
</application>
<uses-permission android:name="android.permission.INTERNET" >
</uses-permission>
</manifest>

Your "items.xml" object has it's height equal to the parent - so only one item will be visible in your listview. Change it to:
<?xml version="1.0" encoding="utf-8"?>
<TextView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content" >
</TextView>

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.

intent not working in android

I am trying to start new activity using an intent but it never works.
two activities
MainActivity.java
Play.java
two layouts
activity_main.xml
layoutplay.xml
it shows THE APPLICATION HAS STOPPED UNEXPECTEDLY
where is the mistake?
MainActivity.java
package com.example.xxx;
import android.os.Bundle;
import android.app.Activity;
import android.content.Intent;
import android.graphics.Typeface;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.TextView;
public class MainActivity extends Activity implements OnClickListener{
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Typeface t= Typeface.createFromAsset(getAssets(), "font.ttf");
TextView tv1= (TextView) findViewById(R.id.textView1);
tv1.setTypeface(t);
tv1.setOnClickListener(this);
}
#Override
public void onClick(View v) {
if(v.getId()==R.id.textView1){
Intent i=new Intent(MainActivity.this,Play.class);
MainActivity.this.startActivity(i);
}
}
}
Play.java
package com.example.xxx;
import android.os.Bundle;
import android.app.Activity;
public class Play extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layoutplay);
}
}
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" >
<ImageView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_alignParentLeft="true"
android:src="#drawable/bouncemenuback"
android:contentDescription="#string/menuback" />
<LinearLayout
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_margin="10dp"
android:orientation="vertical" >
<TextView
android:id="#+id/textView1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
style="#style/my"
android:text="#string/Play"/>
</LinearLayout>
</RelativeLayout>
layoutplay.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=".Play" >
</RelativeLayout>
xxx.manifest
<?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="9" />
<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="com.example.xxx.Play"
android:label="#string/title_activity_play" >
/>
</activity>
</application>
</manifest>

try by removing unused /> inside <activity android:name="com.example.xxx.Play" ..... > /> </activity> in your AndroidManifest.xml
so your code should be :
<activity
android:name="com.example.xxx.Play"
android:label="#string/title_activity_play" >
</activity>

Try replacing your manifest code with this:
<?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="9" />
<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="com.example.xxx.Play"
android:label="#string/app_name" >
<intent-filter>
<action android:name="android.intent.action.PLAY" />
<category android:name="android.intent.category.DEFAULT" />
</intent-filter>
</activity>
</application>
</manifest>
Hope this helps :)

Android application crases when switching activity

I have a problem with an Android aplication. When I try to swich from main activity (PretvornikValut) to another one (Pretvornik) via buttun I get the "Unfortunately aplication stopped working" error. Can anyone help?
PretvornikValut.java
package pretvornik.valut;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
public class PretvornikValut extends Activity implements OnClickListener
{
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
View gumbPretvori = findViewById(R.id.gumb_pretvornik);
gumbPretvori.setOnClickListener(this);
View gumbTecaji = findViewById(R.id.gumb_tecaji);
gumbTecaji.setOnClickListener(this);
}
public void sendMessage(View view) {
Intent intent = new Intent(this, Pretvornik.class);
startActivity(intent);
}
public void onClick(View v) {
switch (v.getId()) {
case R.id.gumb_pretvornik:
Intent i = new Intent(this, Pretvornik.class);
//i.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(i);
break;
case R.id.gumb_tecaji:
Intent tecaj = new Intent(this, Tecaji.class);
tecaj.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(tecaj);
break;
}
}
}
Pretvornik java
package pretvornik.valut;
import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
/**
*
* #author FAKS
*/
public class Pretvornik extends Activity {
/**
* Called when the activity is first created.
*/
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.pretvornik);
}
}
main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#99CCCC"
>
<Button
android:id="#+id/gumb_pretvornik"
android:layout_width="100dp"
android:layout_height="50dp"
android:layout_alignParentLeft="true"
android:layout_alignParentBottom="true"
android:text="Pretvornik"
/>
<Button
android:id="#+id/gumb_tecaji"
android:layout_width="100dp"
android:layout_height="50dp"
android:layout_toRightOf="#+id/OK"
android:layout_alignParentBottom="true"
android:text="Izpis tecajev"
/>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="Izberi zeljeno opcijo"
/>
</LinearLayout>
pretvornik.xml
<?xml version="1.0" encoding="UTF-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:background="#99CCCC"
>
<TextView
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="glavni program"
/>
</LinearLayout>
AndroidManifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="pretvornik.valut"
android:versionCode="1"
android:versionName="1.0">
<application android:label="#string/app_name" android:icon="#drawable/ic_launcher">
<activity android:name="PretvornikValut"
android:label="#string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
<activity
android:name="Pretvornik"
android:label="#string/Pretvornik_valut" >
<meta-data
android:name="PretvornikValut"
/>
</activity>
<activity
android:name="Tecaji"
android:label="#string/Izpis_tecajev" >
<meta-data
android:name="PretvornikValut"
/>
</activity>
</activity>
</application>
</manifest>

Change your manifest xml,
add action for your activities
action android:name="android.intent.action.ACTIVITY"
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="pretvornik.valut"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name="PretvornikValut"
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="Pretvornik"
android:label="#string/hello_world" >
<action android:name="android.intent.action.ACTIVITY" />
</activity>
<activity
android:name="Tecaji"
android:label="#string/hello_world" >
<action android:name="android.intent.action.ACTIVITY" />
</activity>
</application>
</manifest>

Nothing is displayed in screen after running android program

I have written an android application to display a list. Code has taken from an example. There is no error in compiling, but nothing is displayed on after running the application. Expecting you help to solve this problem thanks. Please find below code i used...
Main Activity
public class MainActivity extends ListActivity {
ArrayList<String> listItems=new ArrayList<String>();
ArrayAdapter<String> adapter;
int clickCounter=0;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
listItems.add("Hello");
adapter=new ArrayAdapter<String>(this, android.R.layout.simple_list_item_1, listItems);
setListAdapter(adapter);
}
public void addItems(View v) {
listItems.add("Clicked : "+clickCounter++);
adapter.notifyDataSetChanged();
}
}
mainactivity.xml
<LinearLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<Button
android:id="#+id/addBtn"
android:text="Add New Item"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:onClick="addItems"/>
<ListView
android:id="#android:id/list"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:drawSelectorOnTop="false"
/>
AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.testlistview"
android:versionCode="1"
android:versionName="1.0" >
<uses-sdk
android:minSdkVersion="8"
android:targetSdkVersion="15" />
<application
android:icon="#drawable/ic_launcher"
android:label="#string/app_name"
android:theme="#style/AppTheme" >
<activity
android:name=".MainActivity"
android:label="#string/title_activity_main" >
<meta-data
android:name="android.support.PARENT_ACTIVITY"
android:value="android.app.ListActivity" />
</activity>
</application>
</manifest>

Please add the following intentfilter to the manifest:
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
Android needs this intent filter to know which activity to start.

You may have set the wrong content view in MainActivity.
Try to replace the setContentView statement with the following one:
setContentView(R.layout.mainactivity.xml);