I'm creating an animation bulb app in which there are two image views having blue and green bulb and two buttons(named blue and green).
On pressing them the image1's opacity increases and images2's decreases, the opposite happens when the other button is tapped(alpha values are 1 for both initially), but the animate keyword is showing up in red and the code is not compiling.
MainActivity :
package com.example.honey1.animatedbulb;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.support.v7.widget.AppCompatImageView;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
public class MainActivity extends AppCompatActivity {
public void greenTapped(View view)
{
ImageView blue=(ImageView)findViewById(R.id.bluebulb);
ImageView green=(ImageView)findViewById(R.id.greenbulb);
blue.animate.alpha(1).setDuration(2000);
green.animate.alpha(0).setDuration(2000);
}
public void blueTapped(View view)
{
ImageView blue=(ImageView)findViewById(R.id.bluebulb);
ImageView green=(ImageView)findViewById(R.id.greenbulb);
blue.animate.alpha(0).setDuration(2000);
green.animate.alpha(1).setDuration(2000);
}
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
}
Main activity screenshot :
XML file screenshot :
You just forgot () after animate()
And animate() is method not a property
Use this
blue.animate().alpha(1).setDuration(2000);
green.animate().alpha(0).setDuration(2000);
Instead of this
blue.animate.alpha(0).setDuration(2000);
green.animate.alpha(0).setDuration(2000);
View.animate() is a method, not a property or field.
It should be use like below code, should use .animate() not .animate:
The animate() method on a View object returns an ViewPropertyAnimator
object for the view.It provides a fluent API to typical animations
which can be performed on views.
Your code :
blue.animate.alpha(1).setDuration(2000);
green.animate.alpha(0).setDuration(2000);
Replace to :
blue.animate().alpha(1).setDuration(2000);
green.animate().alpha(0).setDuration(2000);
Related
package com.example.androidx;
import androidx.appcompat.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.TextView;
public class MainActivity extends AppCompatActivity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
}
public void setXiaomiPhone(View view) {
TextView helloTextView = findViewById(R.id.textView);
helloTextView.setText("Hello Xiaomi Phone");
}
}
I need to change the text in Text View, and I also need to change the color and the size of the text. How can I do it?
To change the text color:
textView.setTextColor(ContextCompat.getColor(context, R.color.<name_of_color>));
To change the text size:
textView.setTextSize(TypedValue.COMPLEX_UNIT_SP,14);
To change color, write
helloTextView.setTextColor(Color.RED);
To change size,
helloTextView.setTextSize(14.0f);
You can put your dersired values, such as Color.GREEN or 15.0f
helloTextView.setTextColor
(Color.parseColor("#hex code"));
I'm trying to make a simple app that changes the background color so many times a second. For example, here I'm trying to do it every 12.5 ms (how do I enter the .5 part?)
I'm extremely new to programming, and can't figure out how to call this method/timer to start running.
I run the app, and it opens the activity with a white background and nothing happens.
Since I'm so new, when I look into the Timer() documentation, I'm not really sure what I'm looking at here.... If someone could help that would be amazing.
import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import java.util.Timer;
import java.util.TimerTask;
import static android.support.v7.appcompat.R.attr.background;
/**
* Created by Spader on 3/17/2017.
*/
public class FlashingScreen extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//Remove title bar
this.requestWindowFeature(Window.FEATURE_NO_TITLE);
//Remove notification bar
this.getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
//set content view AFTER ABOVE sequence (to avoid crash)
this.setContentView(R.layout.flashing_screen);
new Timer().scheduleAtFixedRate(new TimerTask(){
#Override
public void run(){
runOnUiThread(new Runnable() {
#Override
public void run() {
//stuff that updates ui
getWindow().getDecorView().setBackgroundColor(Color.WHITE);
getWindow().getDecorView().setBackgroundColor(Color.BLACK);
}
;
});
}
},0,12);
}
}
1.
getWindow().getDecorView().setBackgroundColor(Color.WHITE); getWindow().getDecorView().setBackgroundColor(Color.BLACK);
This always set the black color since it is not on a conditional basis. You may want to use a boolean to switch color every time it executes the runnable.
You shouldn't use getDecorView(). Instead find the root View from your layout xml and change the color.
In Java there is no floating value for times. So you can't have 12.5 ms.
I used samples from similar code to make this, unfortunately I'm not to sure what I did wrong.
The purpose of this app is to output text entered in a field to a TextView, where I changed the color, when a button is pressed.
package edu.wmich.project3
import android.os.Bundle;
import android.app.Activity;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.view.View.OnClickListener;
public class Main extends Activity {
String txtResult;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
Button text =(Button) findViewById(R.id.btnColor0);
final TextView result = ((TextView) findViewById(R.id.txtResult));
text.setOnClickListener(new OnClickListener() {
public void onClick(View v) {
txtResult= getText(R.id.txtField0).toString();
result.setText(txtResult);
}
});
}
}
txtResult = (findViewById(R.id.txtField0)).toString();
will solve...
the problem is that you're using the method getText() from the Activity which has nothing to do with the TextField you're dealing with.
...what is the type of view of R.id.txtField0? I guess with this you can take it from here.
Hoping to get into android app development so I'm doing some basic tutorials just now.
Just trying to get comfortable with the basics at the moment, one of which is using the Typeface class.
package org.me.myandroidstuff;
import android.os.Bundle;
import android.app.Activity;
import android.graphics.Typeface;
import android.view.Menu;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;
public class HelloWorldActivity extends Activity implements OnClickListener
{
private View mainView;
private TextView tbox1;
private Button exitButton;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
mainView=(View)findViewById(R.id.mainView);
mainView.setBackgroundColor(getResources().getColor(R.color.silver));
tbox1 = (TextView)findViewById(R.id.textBox1);
tbox1.setTypeface(Typeface.MONOSPACE);
}
}
The line
tbox1 = (TextView)findViewById(R.id.textBox1);
Has a red cross beside it (I'm using eclipse) with the error
tbox1 cannot be resolved
Its been a while since i have used java, but as i aware the following code
create a new TextView object called tbox1
Assigns the tbox1 object the id specified in the xml for the TextView tag in an external main.xml
Then tbox1 executes the setTypeFace() method on itself?
Obviously I'm going wrong somewhere, any ideas? Something really simple no doubt...
You can't inform us about one error and neglect the others. Look at your code.
Besides what user370305 said, you have other problems. Namely, your Activity, according to the contract, implements OnClickListener but does not override the necessary onClick(View v) method. You must add it for the contract to be met.
So your code should look like:
package org.me.myandroidstuff;
import android.app.Activity;
import android.graphics.Typeface;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.TextView;
public class HelloWorldActivity extends Activity implements OnClickListener {
private View mainView;
private TextView tbox1;
private Button exitButton;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
mainView=(View)findViewById(R.id.mainView);
mainView.setBackgroundColor(getResources().getColor(R.color.silver));
tbox1 = (TextView)findViewById(R.id.textBox1);
tbox1.setTypeface(Typeface.MONOSPACE);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
}
}
Remember, you can't talk about errors until you fix every other that might cause other errors to be falsely reported.
First try to set setContentView(R.layout.yourlayoutfilename); in onCreate().
1.) Delete line super.onCreate(savedInstanceState);
2.) Retype super.onCreate(savedInstanceState);
3.) Clean the Project
4.) Build the Project
I am rather new to Android programming in general and am having particular difficulty with the xml/java UI shuffle... I have a layout which I would like to use as the view displayed when a custom, view class is instantiated in the activity class. This much works fine by simply calling
setContentView(R.layout.mylayout) ;
in the activity or from the custom view class through a handle to the activity. The trouble comes when I wish to interact with the widgets on the layout-- I've tried getting a handle on the buttons with
myButton = (Button) findViewById(R.id.mybuttonid);
and separately with
Button myButton = new Button(contextHandle);
myButton = (Button) findViewById(R.layout.mybuttonid);
but in both cases whenever I try to call any methods from the assumed myButton object I get a NullPointerException in the logcat report; evidently myButton is not properly instantiated in either case given above. What is the proper way to instantiate components of a view in a case like this that combines xml and java so that they can call methods dynamically?
thanks,
CCJ
EDIT: Thanks all for the replies, but I think up to 8/1/2011 the advice has been mostly targeted at an implementation wherein the widgets are to be instantiated in the activity class; I wish to instantiate widgets from an xml layout in a custom view class-- a class completely separate from the activity class which extends View and implements its own OnClickListener interface. Below is my code:
MyActivity Class:
package com.ccg.myactivity;
import android.app.Activity;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.RadioButton;
public class MyActivity extends Activity implements OnClickListener {
private boolean touched = false;
private RadioButton myRB;
private Button runB;
private CustomView myView;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.mainlayout);
myRB = (RadioButton) findViewById(R.id.testrb);
runB = (Button) findViewById(R.id.goButton);
//set onClick listeners for activity class
runB.setOnClickListener(this);
}
public void onResume(){
super.onResume();
}
public void onClick(View v) {
// do something when the button is clicked
if (myRB.isChecked()){
setContentView(R.layout.mylayout);
myView = new CustomView(this,this); //passing in activity and context
//handles to custom View class
//myView.getAnotherB().setOnClickListener(this); //commented out as we
//don't want to register the custom view's button with the Activty class's
//OnClickListener; instead it should be registered with the custom View class's own
//OnClickListener implementation.
}
else{
Log.d("me","alt click");
}
}
}
CustomView Class:
package com.ccg.myactivity;
import android.app.Activity;
import android.content.Context;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.*;
import android.view.View.OnClickListener;
public class CustomView extends View implements OnClickListener{
private Button anotherB;
private Context contextHandle;
private Activity actHandle;
public CustomView(Context context, Activity act) {
super(context);
contextHandle = context;
actHandle = act;
//anotherB = new Button(contextHandle); //this shouldn't be necessary for
//instantiation from XML widget
initCustomView();
}
public void initCustomView(){
anotherB = (Button) findViewById(R.id.nextbutton);
anotherB.setOnClickListener(this);
}
public Button getAnotherB(){
return anotherB;
}
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Log.d("me", "Got the custom click!");
}
}
mainlayout.xml from which the default view is made:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:id="#+id/widget474"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical">
<RadioGroup android:id="#+id/widget30" android:orientation="horizontal"
android:layout_x="2dip" android:layout_y="57dip" android:layout_width="match_parent"
android:layout_height="wrap_content">
<RadioButton android:layout_height="wrap_content" android:id="#+id/testrb"
android:textSize="15sp" android:text="Run" android:layout_width="wrap_content"
android:textColor="#ffff99ff"></RadioButton>
</RadioGroup>
<Button android:layout_width="wrap_content" android:text="#string/RUN"
android:id="#+id/goButton" android:layout_height="wrap_content"
android:layout_x="222dip" android:layout_y="110dip"></Button>
</LinearLayout>
mylayout.xml from which the custom view's layout is created:
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
android:id="#+id/widget0"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical">
<Button android:id="#+id/nextbutton" android:layout_height="wrap_content"
android:layout_width="wrap_content" android:text="work!!!"
>
</Button>
</LinearLayout>
okay, if anybody can explain why any method calls from the button object anotherB (anotherB.setOnClickListener(this) above, but also the simpler anotherB.bringToFront()) cause a force close and a nullpointerexception in logcat with the above implementation I would be most appreciative. thanks!
CCJ
I would declare your button outside of onCreate without the contextHandle parameter... The context will be imbedded in your button upon instantiation (as I understand it).
try:
class YOUR_CLASS {
Button myButton;
onCreate() {
myButton = (Button) findViewById(R.id.WHATEVER_YOU_CALLED_IT_IN_XML);
then you can set an onClickListener or other abilities (you can google that, its easy)
myButton.setOnClickListener(myOnClickListener);
myButton.setText("click me!");
}
}
This sometimes happens to me when the import isn't correct. Sometimes Eclipse will fill in the import as:
import android.R;
of course, this will never find your ID. You should either not have an import, or have something like
import com.myco.mytestapp.R;
If you do that, then the first way of doing it is correct:
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.mylayout);
Button b = (Button) findViewById(R.id.mybutton);
}
Okay, thanks to some advice from the android developers google group I think I've found the answer to at least the most pressing concern (the NPE and force close):
I needed to override onFinishInflate in my custom View class; it is at that point that my XML layout child views (like anotherB) are truly instantiated. The class now looks like this
package com.ccg.myactivity;
import android.app.Activity;
import android.content.Context;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.ViewGroup;
import android.widget.*;
import android.view.View.OnClickListener;
public class CustomView extends View implements OnClickListener{
private Button anotherB;
private Context contextHandle;
private Activity actHandle;
public CustomView(Context context, Activity act) {
super(context);
contextHandle = context;
actHandle = act;
//anotherB = new Button(contextHandle); //this shouldn't be necessary for
//instantiation from XML widget
initCustomView();
}
public void initCustomView(){
anotherB = (Button) findViewById(R.id.nextbutton);
anotherB.setOnClickListener(this);
}
public Button getAnotherB(){
return anotherB;
}
#Override
public void onFinishInflate(){
anotherB.setOnClickListener(this); //it seems any addressing of child
//views of the layout [the widgets] need to be made after the
//framework calls this method.
}
#Override
public void onClick(View arg0) {
// TODO Auto-generated method stub
Log.d("me", "Got the custom click!");
}
}
Now it pulls up the layout properly and does not throw an NPE. Of course, the onClickListener callback still isn't working right (the message 'Got the custom click!' never appears in logcat), but that's another issue...
thanks all
CCJ
Okay, finally had some time to revisit this issue and I believe I've found the answer:
First, before the xml layout or its components can be addressed they need to be inflated. I knew this, but I wasn't sure when exactly they were inflated. It turns out that setContextView (and probably addContextView) trigger xml inflations. In order to have completely modular activity/view classes, I needed to do something like the following:
Activity Class--
package com.ai.ultimap;
import com.ai.ultimap.views.HomeView;
import android.app.Activity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup.LayoutParams;
public class UltiMapActivity extends Activity {
private View hv;
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
hv = new HomeView(this);
}
}
Custom View Class-
package com.ai.ultimap.views;
import com.ai.ultimap.R;
import android.app.Activity;
import android.os.Bundle;
import android.view.*;
import android.widget.*;
import android.view.View.OnClickListener;
public class HomeView extends View implements OnClickListener{
private RadioButton twodRB;
private RadioButton threedRB;
private TextView locTV;
private EditText editlocET;
public HomeView(Activity hAct) {
super(hAct);
//THE FOLLOWING LINE INFLATES-- IT (or another function which calls xml inflation)
//MUST COME BEFORE ANY JAVA ADDRESSING OF WIDGETS IN
//THE XML LAYOUT
//Also note that even though you could invoke findViewById from a class extending
//View, in this case you must use hAct.findViewById. I believe this is due to the
//fact that the activity referenced by hAct is the object responsible for inflating
//the xml and thus the widgets need to be instantiated from it.
hAct.setContentView(R.layout.ultimap);
twodRB = (RadioButton) hAct.findViewById(R.id.twodRBV);
threedRB = (RadioButton) hAct.findViewById(R.id.threedRBV);
locTV = (TextView) hAct.findViewById(R.id.locationTV);
editlocET = (EditText) hAct.findViewById(R.id.locationETV);
//After instantiation however they can be freely accessed from java in
//non-activity classes, which is the point; see the next line...
twodRB.setOnClickListener(this);
}
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
locTV.setText("yo");
}
}
This code works properly to load up the pre-defined xml view ultimap.xml and then address the widgets dynamically from Java (completely outside the activity class), changing the text of the location text view from 'Location' to 'yo' when the twodRB radiobutton is clicked!
Hope this helps some googlers :)
-CCJ