Develop Reference

How to show list of Strings in a Textview by scrolling one by one with play and pause actions in android

I have 10 strings and I need to show all these strings in a textview one by one sliding to left automatically, and I have 2 buttons one button is to stop that and one button is start autoscrolling again. i.e when I click on start button, textview will be displayed with first string and then next string something like autoscrolling view pager.When click on stop button Textview should freeze with current string.Can anyone help me on this? how can I achieve this?
Thanks in-advance.

You should try to give attempt to write your code and then ask for suggestion based on your logic. However i would suggest you to make use of the following link
Example:
implementation 'com.github.smarteist:autoimageslider:1.2.0'
implementation 'com.github.bumptech.glide:glide:4.7.1'
Just put the view in the layout xml like this:
<com.smarteist.autoimageslider.SliderLayout
android:layout_width="match_parent"
android:layout_height="300dp"
android:layout_alignParentTop="true"
android:id="#+id/imageSlider"/>
And implement the slider with your own programming Here is an example of the implementation of this library in java :
SliderLayout sliderLayout;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
sliderLayout = findViewById(R.id.imageSlider);
sliderLayout.setIndicatorAnimation(SliderLayout.Animations.FILL); //set indicator animation by using SliderLayout.Animations. :WORM or THIN_WORM or COLOR or DROP or FILL or NONE or SCALE or SCALE_DOWN or SLIDE and SWAP!!
sliderLayout.setScrollTimeInSec(1); //set scroll delay in seconds :
setSliderViews();
}
private void setSliderViews() {
for (int i = 0; i <= 3; i++) {
SliderView sliderView = new SliderView(this);
//You can ignore the next switch case as you dont have image requirement
/* switch (i) {
case 0:
sliderView.setImageUrl("https://images.pexels.com/photos/547114/pexels-photo-547114.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260");
break;
case 1:
sliderView.setImageUrl("https://images.pexels.com/photos/218983/pexels-photo-218983.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260");
break;
case 2:
sliderView.setImageUrl("https://images.pexels.com/photos/747964/pexels-photo-747964.jpeg?auto=compress&cs=tinysrgb&h=750&w=1260");
break;
case 3:
sliderView.setImageUrl("https://images.pexels.com/photos/929778/pexels-photo-929778.jpeg?auto=compress&cs=tinysrgb&dpr=2&h=750&w=1260");
break;
}
sliderView.setImageScaleType(ImageView.ScaleType.CENTER_CROP);*/
sliderView.setDescription("setDescription " + (i + 1));
final int finalI = i;
sliderView.setOnSliderClickListener(new SliderView.OnSliderClickListener() {
#Override
public void onSliderClick(SliderView sliderView) {
Toast.makeText(MainActivity.this, "This is slider " + (finalI + 1), Toast.LENGTH_SHORT).show();
}
});
//at last add this view in your layout :
sliderLayout.addSliderView(sliderView);
}
}

How can I change Text of Textview from other funcion?

this is my first question so I hope to make it clear.
I have one textView with some numerical text and next to it one button with one click listener and what I want is that when you click on the button the numerical value (>=0) of the TextView decrements in one.
Here is part of my code:
TextView Counter = new TextView(this);
if (intSeries != 0)
Counter.setText(Integer.toString(intSeries));
else
Counter.setText("0");
Counter.setId(4);
tablaContador.addView(Counter,Tr);
Button Done = new Button(this);
Done.setText("-1");
if (intSeries != 0)
Done.setVisibility(View.VISIBLE);
else
Done.setVisibility(View.GONE);
Done.setId(6);
Done.setOnClickListener(this);
And this is the onClick funcion (part of it):
#Override
public void onClick(final View v) {
// TODO Auto-generated method stub
switch (v.getId()) {
case 6:{
TextView text = (TextView)findViewById(4);
int series = Integer.parseInt(text.getText().toString());
series--;
text.setText(series);
if (series==0){
Button boton = (Button)findViewById(6);
boton.setVisibility(View.GONE);
}
}
}
}
The error is when I try to make the setText inside the onClick function, I hope it can be fixed or maybe recieve other idea to do it.
Thank you so much.

I would avoid all this hardcoding of Ids, use resources instead.
Your call to
text.setText(series)
is passing an int. The only valid setText(int resId) overload expects a resource associated with the int value, i.e. a string resource.
Convert your series value to a string.
Something like:
text.setText(Integer.toString(series));

You should setup series as an integer. And increase/descrease it as you wish. When you want to change the button's text convert the int to String.
Instead of:
text.setText(series);
use:
text.setText(String.valueOf(series));

Variablenames in java can't start with a capital letter. That is reserved for classnames.
Counter -> counter
Done -> done

I tried this and it worked:
//Create onClickListener
OnClickListener pickChoice = new OnClickListener()
{
public void onClick(View v)
{
TextView txt = (TextView) findViewById(4);
int number = Integer.valueOf(txt.getText().toString());
txt.setText(String.valueOf(number -1));
}
};
//Create layout
LinearLayout lnLayout = new LinearLayout(this);
lnLayout.setOrientation(LinearLayout.VERTICAL);
TextView txt = new TextView(this);
txt.setId(4);
txt.setText("0");
lnLayout.addView(txt);
Button Done = new Button(this);
Done.setText("-1");
Done.setId(6);
Done.setOnClickListener(pickChoice);
lnLayout.addView(Done);
setContentView(lnLayout);
Where are you creating your button inside? an activity? the part where you pass the onClickListener to the button doesn't make sense, maybe the button is getting a wrong listener and gets you an error every time you press the button ?
The code should be easy to understand, if there is anything you need me to explain please ask :)

Android calculator buttons

I am trying to make a calculator for Android. Here is the code for my buttons:
int[] button_ids = {
R.id.BtnNum0, R.id.BtnNum1, R.id.BtnNum2, R.id.BtnNum3, R.id.BtnNum4, R.id.BtnNum5, R.id.BtnNum6,
R.id.BtnNum7, R.id.BtnNum8, R.id.BtnNum9, R.id.BtnAdd, R.id.BtnSub, R.id.BtnDiv, R.id.BtnMult,
R.id.BtnClear, R.id.equals
};
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
EditTextValue = (EditText) findViewById(R.id.editText1);
TVValue = (TextView) findViewById(R.id.textView1);
buttons = new ArrayList<Button>();
for(int id : button_ids) {
Button button = (Button)findViewById(id);
button.setOnClickListener(this);
buttons.add(button);
}
}
How I can change this part to a block of code where I won't have to declare the IDs of the buttons? (e.g. R.id.BtnNum0)
int[] button_ids = {
R.id.BtnNum0, R.id.BtnNum1, R.id.BtnNum2, R.id.BtnNum3, R.id.BtnNum4, R.id.BtnNum5, R.id.BtnNum6,
R.id.BtnNum7, R.id.BtnNum8, R.id.BtnNum9, R.id.BtnAdd, R.id.BtnSub, R.id.BtnDiv, R.id.BtnMult,
R.id.BtnClear, R.id.equals
};
I have been searching for an answer, but I still can't find a solution.

What you can do, since this code seems to only set a single OnClickListener for all Buttons, is to do it in xml
For each Button set
android:onClick="functionName"
then in your code you can do away with all of the id's and your for loop. In Java just create a function like
public void functionName(View v)
{
switch (v.getId())
{
case R.id.buttonId:
// do work for this Button
break;
...
}
The way you are doing it is fine but this is how I prefer to handle this situation. You just have to give all of the Buttons the same function name in xml then use that name as your function name in Java. You also just have to be sure to declare the function with a void return type and make sure it takes a View as its one and only parameter as in my example.
The Button Docs also have an example of this

in your layout file add this to every button
<Button
...
android:onClick="btnClicked"
.../>
then in your code add this method and check for each button in this method
public void btnClicked(View v)
{
switch(v.getId())
{
case R.id.BtnNum0:
// your code
break;
....
}
}

That is likely the best solution unfortunately, unless you use some sort of annotation framework which still doesn't cut down much on the boilerplate.
edit:
You could try to get a pointer to whatever ViewGroup is holding the Button views and then getting all of its children, and then looping through them while casting them to Buttons as you go.
For example: If your Button objects in XML are housed in a LinearLayout, you could get the pointer to that and do something like this:
for(int i=0; i < ((ViewGroup)v).getChildCount(); ++i) {
Button nextChild = (Button) ((ViewGroup)v).getChildAt(i);
}
Of course, I recommend against this, but it is still a possibility.

As trevor-e suggested, you can give an annotation processor a try. Android Annotations can simplify your code to:
#Click
public void BtnNum0() {
// Button 0 clicked
}
#Click
public void BtnNum1() {
// Button 1 clicked
}
// etc.
If you go this route, please do try to use names following the Java convention as the button names correspond with function names.

Some alternative to hundreds of buttons

Im going to write some android app, which will basically consists of two activities. So first should have a lot of buttons (100+) and on click on any of them I will just get some special id and move to second activity. But is there any alternative to declare that hundreds of buttons and copy/paste one piece of code to every of them setting almost same onClickLister? Is there any special construction? Thanks
Edit: every of buttons are actually indexed from 1 to n. And on the click second activity will be launched and get that index to show it. I cant basically use any spinner or smth else, because there will be 3 rows of clickable things and each of them carring different images
Edit 2: so, to give you an idea, im going to do some table of buttons like in Angry Birds menu when you actually choosing the level you want to play. So, on click you will get id of button and start second activity

Call the method to add buttons
private void addButton(){
LinearLayout view = (LinearLayout) findViewById(R.id.linear_layout_id_here);
Button btn = null;
int w = 50;
int h = 25;
for(int i=1; i<100; i++) {
btn = new Button(this);
btn.setLayoutParams(new LayoutParams(w,h));
btn.setText("button " +i);
btn.setTag(""+i);
btn.setOnClickListener(onClickBtn);
view.addView(btn);
btn = null;
}
}
Call this method for handling onclick on button
private View.OnClickListener onClickBtn = new View.OnClickListener() {
public void onClick(View view) {
final int tag = Integer.parseInt(view.getTag().toString());
switch (tag) {
case 1:
// Do stuff
break;
case 2:
// Do stuff
break;
default:
break;
}
}
};

You should use a ListView.
ListViews are great for handling a lot of items at the same time. They are also natural for the user. Additionally, you use only one click listener - OnItemClickListener.
There's a useful example on how to work with ListViews in the Android Referenence.

You may add buttons in code, something like this:
#Override
public void onCreate(Bundle savedInstanceState) {
/*your code here*/
GroupView gw =findViewById(R.id.pnlButtonscontainer); //find the panel to add the buttons
for(int i=0; i<100; i++) {
Button b = new Button(this);
b.setLayoutParameters(new LayoutParameters(w,h));
b.settext = i+"";
b.setOnClickListener(new OnClickListener(){
});
}
}
I coded directly into browser, so some syntax error may appear in my code, but this is the point, a way, not the only one, to add 100 buttons.

Dynamically creating Buttons and setting onClickListener

I have problem with handling dynamically created Buttons on Android. I'm creating N buttons and I have to do the same method when button is clicked but I have to know which button is clicked.
for (int i = 0; i < NO_BUTTONS; i++){
Button btn = new Button(this);
btn.setId(2000+i);
...
btn.setOnClickListener((OnClickListener) this);
buttonList.addView(btn);
list.add(btn);
Cucurrently I'm adding ID to every button and I'm using the method below to see which button was clicked. (line btn.setId(2000+i); and btn.setOnClickListener((OnClickListener) this);). This method is also implemented in the activity.
#Override
public void onClick(View v) {
switch (v.getId()){
case 2000: selectButton(0);
break;
...
case 2007: selectButton(7);
break;
}
}
This doesn't look good to me so i'm asking is there some better way to do this? or how to send some information to onclick event? any suggestions?

You could create a method that returns an onclickListener and takes a button as a parameter. And then use that method to set the onClicklistener in the first loop you have..
Update: code could be soemthing along these lines:
View.OnClickListener getOnClickDoSomething(final Button button) {
return new View.OnClickListener() {
public void onClick(View v) {
button.setText("text now set.. ");
}
};
}
as a method in the activity and then use it in the loop like this
button.setOnClickListener(getOnClickDoSomething(button));

I got one solution for this..
use this code in onCreate
linear = (LinearLayout) findViewById(R.id.linear);
LayoutParams param = new LinearLayout.LayoutParams(
LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT, 1.0f);
Button[] btn = new Button[num_array_name.length];
for (int i = 0; i < num_array_name.length; i++) {
btn[i] = new Button(getApplicationContext());
btn[i].setText(num_array_name[i].toString());
btn[i].setTextColor(Color.parseColor("#000000"));
btn[i].setTextSize(20);
btn[i].setHeight(100);
btn[i].setLayoutParams(param);
btn[i].setPadding(15, 5, 15, 5);
linear.addView(btn[i]);
btn[i].setOnClickListener(handleOnClick(btn[i]));
}
after onCreate create one method of return type View.OnClickListener like this..
View.OnClickListener handleOnClick(final Button button) {
return new View.OnClickListener() {
public void onClick(View v) {
}
};
}

Button.OnClickListener btnclick = new Button.OnClickListener(){
#Override
public void onClick(View v) {
// TODO Auto-generated method stub
Button button = (Button)v;
Toast.makeText(getApplicationContext(), button.getText().toString(),2).show();
}
};
call this listener by btn.setOnClickListener(btnclick);

View IDs should not be used for these purposes as View Ids are generated on compilation time depending on IDs defined in xml layout files.
Just place your own IDs in the setTag() method which is available at the View level (so Buttons inherit them). This "tag" can be anything that allow you to recognize a View from others. You retrieve its value with getTag().

instead use setTag() function to distinct easily.
for(int i=0;i<4;i++) {
Button btn = new Button(this);
btn.setTag(i);
btn.setOnClickListener(new View.OnclickListener() {
#Override
public void onClick(View v) {
int i=v.getTag();
switch(i) {
case 1: btn.setText(i);
break;
case 2: btn.setText(i);
break;
case 3: btn.setText(i);
break;
case 4: btn.setText(i);
break;
default: btn.setText("Others");
}
}
}

"This doesn't look good to me" why not? doesn't it work? You could also create a static member variable holding a list of all added buttons, and then look for the clicked button in that list instead.

I don't know why you would want to create N buttons, it looks like your value of N is greater than 10 at least, if you are not trying to show them all at once (I mean fit all of them into one single screen, no scrolling) you could try to recycle the invisible buttons just like we do for list view using a list view holder. This would reduce your memory footprint and boost performance, and differentiate the buttons based either on the text you set on them or a tag or you can even hold a reference to those small number of buttons.

Is preferable not to mess up with the ids, setTag and getTag methods were designed for that purpose, it's the fast and clean way to set a bunch of button listeners on a dynamic layout
This answer may you help:
https://stackoverflow.com/a/5291891/2804001

public class MainActivity extends Activity implements View.OnClickListener
{
LinearLayout linearLayout;
Button [] button;
View.OnClickListener listener;
#Override
public void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
linearLayout=(LinearLayout)findViewById(R.id.parent_lay);
String[] array={"U123","U124","U125"};
int length=array.length;
System.out.println("11111111111111111111111111");
button=new Button[length];
for(int i=0;i<length;i++)
{
button[i]=new Button(getApplicationContext());
button[i].setId(i);
button[i].setText("User" + i);
button[i].setOnClickListener(this);
linearLayout.addView(button[i]);
}
}
#Override
public void onClick(View view)
{
view.getId();
Button button=(Button)findViewById(view.getId());
button.setText("Changed");
}
}