I am working in android, i want to make a scrollview.
this is my code for that :
package com.pericent;
import android.app.Activity;
import android.app.TabActivity;
import android.content.Intent;
import android.content.res.Resources;
import android.os.Bundle;
import android.util.Log;
import android.view.ViewGroup.LayoutParams;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;
import android.widget.TabHost;
import android.widget.TextView;
public class HelloTabWidget extends Activity {
private String TAG="HelloTabWidget";
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
Log.v(TAG,"i am just before everything");
HorizontalScrollView hr=new HorizontalScrollView(this);
hr.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.FILL_PARENT));
LinearLayout layout=new LinearLayout(this);
LinearLayout mainlayout=new LinearLayout(this);
mainlayout=(LinearLayout)findViewById(R.id.upper1);
layout.setLayoutParams(new LayoutParams(LayoutParams.FILL_PARENT,LayoutParams.WRAP_CONTENT));
Log.v(TAG,"i am just after the declarations");
for(int i=0;i<100;i++){
TextView txt=new TextView(this);
txt.setText("Text " + i );
layout.addView(txt);
}
Log.v(TAG,"i am after the for loop");
hr.addView(layout);
mainlayout.addView(hr);//<<---this is creating NullPointerException
setContentView(R.layout.cecking);
Log.v(TAG,"i am after the everything");
}
}
and this my cecking.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="#+id/upper1">
</LinearLayout>
whenever i run the program, this error is occurred:-
Unable to start activity ComponentInfo{com.pericent/com.pericent.HelloTabWidget}: java.lang.NullPointerException
and in this line the error is occurred:- mainlayout.addView(hr);
please help me to find out the reason of error.
Thank you in advance.
You are not setting any layout for the Activity
as well as you are not Inflating checking.xml for that Activity.
That's why mainlayout cannot be found and cause NullPointerException
Try this way:
checking.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="fill_parent">
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent" android:layout_height="fill_parent" android:id="#+id/upper1">
</LinearLayout>
</LinearLayout>
and then set your layout inside onCreate() of the Activity
like this:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
this.setContenView(R.layout.checking);
mainlayout=(LinearLayout)findViewById(R.id.upper1);
}
This might be because you haven't set
.setLayoutParams(new Layout...
for mainlayout, the error statement line object.
Related
I'm trying to get a ListView to show the contents of a simple array but my program crashes at the setAdapeter line. As I understand this is supposed to be because the final value comes out as null but I don't see why that would be the case or how to fix it. I have already tried using ArrayAdapeter instead as well as catching the null exception with a try block. The former changes nothing and the latter simply shows a blank activity with no list to speak of. Please help.
Here's Main Activity
package ballton.fowdeckbuilder;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.ListAdapter;
import android.widget.ArrayAdapter;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Button btnDecks = (Button) (findViewById(R.id.btnDecks));
Button btnCards = (Button) (findViewById(R.id.btnCards));
btnDecks.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, DeckCatalogue.class));
}
});
btnCards.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
startActivity(new Intent(MainActivity.this, CardCatalogue.class));
}
});
}
}
Here's the activity with the Problem
package ballton.fowdeckbuilder;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.support.v7.widget.Toolbar;
import android.util.Log;
import android.widget.ArrayAdapter;
import android.widget.ListAdapter;
import android.widget.ListView;
public class DeckCatalogue extends AppCompatActivity {
ListView Ldecks;
String TAG = "TAG";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_deck_catalogue);
Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
setSupportActionBar(toolbar);
Ldecks = (ListView) (findViewById(R.id.DeckList));
String Decks[] = new String[] {"Faria","Melgis"};
ListAdapter feed = (new ArrayAdapter<String>(this, R.layout.show_deck, Decks));
Ldecks.setAdapter(feed);
}
}
Here's the Layout for that activity
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_behavior="#string/appbar_scrolling_view_behavior"
tools:context="ballton.fowdeckbuilder.DeckCatalogue"
tools:showIn="#layout/activity_deck_catalogue">
<ListView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:id="#+id/DeckList"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
And Here's the layout XML I use for the list times
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical" android:layout_width="match_parent"
android:layout_height="match_parent">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="?android:attr/textAppearanceSmall"
android:text="Small Text"
android:id="#+id/Deck" />
</LinearLayout>
Use this code instead of yours:
ListAdapter feed = (new ArrayAdapter<String>(this, R.layout.show_deck, R.id.Deck, Decks));
This happened because you must supply the resource ID (as your xml: R.id.Deck) for the TextView you used for ListView.
I'm relatively new to android development and I'm trying to find a way to inflate a view repeatedly each time when a button is pressed, in a different location, so every inflated view has its own position:
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.RelativeLayout;
import android.widget.TextView;
public class teamCreateScreen extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.team_locate_layout);
}
public void createTeam(View view) {
final RelativeLayout rlTeam = (RelativeLayout) findViewById(R.id.rlTeam);
View teamBox = View.inflate(this, R.layout.team_box, rlTeam);
final TextView teamBoxView = (TextView) findViewById(R.id.team_task_box);
teamBoxView.setX(0);
teamBoxView.setY(230);
}
}
The XML code of the layout:
<?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"
android:id="#+id/rlTeam">
<Button
android:layout_width="60dp"
android:layout_height="60dp"
android:id="#+id/teamAddBtn"
android:text="+"
android:textSize="30sp"
android:onClick="createTeam"/>
</RelativeLayout>
XML code of the view that's being inflated:
<?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">
<TextView
android:layout_width="192dp"
android:layout_height="120dp"
android:id="#+id/team_task_box"
android:text="New Team" />
</RelativeLayout>
I want to use the same view to inflate multiple boxes with different coordinates in the layout. Every time I press the button to inflate the view again it inflates the box in the same coordinates so they overlap. I need to make the second box to appear to the first one's right, the third below 1st and so on, much like a grid of boxes.
Try this code and tell me whether it works. Remove the inflating of layout
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.widget.RelativeLayout;
import android.widget.TextView;
public class teamCreateScreen extends Activity {
int i=0;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.team_locate_layout);
}
public void createTeam(View view) {
final RelativeLayout rlTeam = (RelativeLayout) findViewById(R.id.rlTeam);
RelativeLayout.LayoutParams relativeParams = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
TextView tv=new TextView(getApplicationContext());
if(tv.getId()>0) {
relativeParams.addRule(RelativeLayout.BELOW, tv.getId());
}
tv.setId(i);
r1Team.addView(tv, relativeParams);
i++;
}
}
Declare int i=0; as a global variable and increment it in the createTeam() method.
I have to create a edit text one by one below inside custom dialog while clicking the button.
So far I have tried and created one edit text on clicking the button in custom dialog.
MainActivity.java:
Below I am shown the code what I had tried so far:
Edited:
import android.support.v7.app.ActionBarActivity;
import android.app.Dialog;
import android.os.Bundle;
import android.view.Gravity;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.ViewGroup;
import android.view.ViewGroup.LayoutParams;
import android.widget.Button;
import android.widget.EditText;
import android.widget.FrameLayout;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
public class MainActivity extends ActionBarActivity {
private Button button;
private LinearLayout ll;
EditText et;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
button = (Button) findViewById(R.id.addBtn);
button.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
final Dialog dialog = new Dialog(MainActivity.this);
//setting custom layout to dialog
dialog.setContentView(R.layout.custom_dialog_layout);
dialog.setTitle("Add List");
//adding button click event
Button createEditText = (Button) dialog.findViewById(R.id.button);
createEditText.setOnClickListener(new OnClickListener() {
#Override
public void onClick(View v) {
// dialog.dismiss();
et= new EditText(MainActivity.this);
FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
params.gravity = Gravity.CENTER;
dialog.addContentView(et,params);
((LinearLayout) dialog.findViewById(R.id.container)).addView(et);
}
});
dialog.show();
}
});
}
}
custom_dialog_layout.xml:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="fill_parent"
android:layout_height="fill_parent" >
<LinearLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
>
<Button
android:id="#+id/button"
android:layout_width="100dp"
android:layout_height="wrap_content"
android:layout_below="#+id/image"
android:layout_centerHorizontal="true"
android:layout_marginTop="100dp"
android:text="Next" />
</LinearLayout>
</RelativeLayout>
I don't know how to create infinite number of edittext one by one below.Anyone can help me with this.Thank you.
The way I've done it before is to have some containing layout (linearlayout, usually) and add my views to that container. Rough code:
LinearLayout container = (LinearLayout) findViewById(R.id.container);
and in your onclick listener
EditText edit = new EditText(MainActivity.this);
container.addView(edit);
Edit
Okay, after managing to absolutely miss the point of your question in my initial post, I went and checked out what was going on. What's happening (I think) is that it IS actually adding more edittexts, but they're all on top of each other so it looks like that it's not. So here's what you have to do, which plays into what I wrote above:
In your custom dialog view, add a linearlayout container
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/container"></LinearLayout>
and in your onclick, you add your edit texts to the linearlayout, NOT the dialog view
et= new EditText(TestActivity.this);
FrameLayout.LayoutParams params = new FrameLayout.LayoutParams(FrameLayout.LayoutParams.WRAP_CONTENT, FrameLayout.LayoutParams.WRAP_CONTENT);
params.gravity = Gravity.CENTER;
((LinearLayout) dialog.findViewById(R.id.container)).addView(et);
and that should work.
I'm trying to configure AdMod in my first Android project. When I try to run the app, findViewByID always returns null.
Here's the code of my main activity:
import android.app.Activity;
import android.content.Context;
import android.content.res.Configuration;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.os.Bundle;
import android.os.PowerManager;
import android.os.PowerManager.WakeLock;
import android.view.Window;
import android.view.WindowManager;
public abstract class MyAndroidApp extends Activity {
AdView adView;
public static final String MY_PUBLISHER_ID = "***********";
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
AdRequest adRequest = new AdRequest();
adRequest.addTestDevice(AdRequest.TEST_EMULATOR);
adView = new AdView(this, AdSize.BANNER, MY_PUBLISHER_ID);
//R.id.main has value, I can see it in Eclipse
RelativeLayout mainLayout = (RelativeLayout) findViewById(R.id.main);
if ( mainLayout == null )
Log.d("Error","Layout is null");
else
mainLayout.addView(adView);
adView.loadAd(adRequest);
The XML File (under res\layout) has the following:
<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=".MyApp"
android:id="#+id/main">
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_centerHorizontal="true"
android:layout_centerVertical="true"
android:text="#string/hello_world" />
</RelativeLayout>
When I debug, I can see value for R.id.main. However, the value of mainLayout is still null.
Thanks in advance.
Problem is that you are not calling setContentView() in onCreate() method:
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.layoutId);
RelativeLayout mainLayout = (RelativeLayout) findViewById(R.id.main);
}
Without it you will get always NPE because UI elements don't have created instances(purpose of setContentView method) and View returned by findViewById() is assigned to NULL.
So add this one line and it should work.
The setContentView method should be called with appropriate layout before calling findViewById. It is usually called in onCreate(Bundle savedInstance) method.
I've created a custom ViewGroup based on a LinearLayout.
ClearableEditText.java
package test.todolist;
import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.LinearLayout;
public class ClearableEditText extends LinearLayout{
private EditText editText;
private Button button;
public ClearableEditText (Context context){
super (context);
String service = Context.LAYOUT_INFLATER_SERVICE;
LayoutInflater li = (LayoutInflater)getContext ().getSystemService (service);
li.inflate (R.layout.clearable_edit_text, this, true);
editText = (EditText)findViewById (R.id.clearEditText);
button = (Button)findViewById (R.id.clearButton);
configButton ();
}
private void configButton (){
button.setOnClickListener (new Button.OnClickListener (){
public void onClick (View v){
editText.setText ("");
}
});
}
}
clearable_edit_text.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<EditText
android:id="#+id/clearEditText"
android:layout_width="match_parent"
android:layout_height="wrap_content"
/>
<Button
android:id="#+id/clearButton"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="#string/clear"
/>
</LinearLayout>
How can I use ClearableEditText now?
I've tried to put a node inside a layout (main.xml) in 2 ways:
<test.todolist.ClearableEditText/>
and
<test.todolist.clearable_edit_text/>
but none of them have worked.
My main.xml:
<?xml version="1.0" encoding="utf-8"?>
<test.todolist.ClearableEditText/>
My ToDoList.java (main activity):
package test.todolist;
import android.app.Activity;
import android.os.Bundle;
public class ToDoList extends Activity{
#Override
public void onCreate (Bundle savedInstanceState){
super.onCreate (savedInstanceState);
setContentView (R.layout.main);
}
}
Thanks.
Solved. The main.xml should be like:
<?xml version="1.0" encoding="utf-8"?>
<merge xmlns:android="http://schemas.android.com/apk/res/android">
<test.todolist.ClearableEditText
android:layout_width="match_parent"
android:layout_height="wrap_content"/>
</merge>
First, merge tag because it is needed when using custom views. My custom view have a LinearLayout root, so it's inefficient if I set another LinearLayout or FrameLayout root in main.xml to use my custom view. merge solves that.
And second, all views must have the layout_width and layout_height attributes.