I'm confronted with the Problem of slow Performance...
Just take a case:
RelativeLayout myLayout = (RelativeLayout) findViewById(R.id.myrlLayout);
//Adding now 100 Buttons with 100 TextViews below each Button(just a example)
for(i=0;i<100;i++) {
Button btn = new Button(this);
btn.setId(i+1); //Should be a positive integer
//set LayoutParams for Button
RelativeLayout.Layoutparams btn_layoutparams = new RelativeLayout.LayoutParams....
....
myLayout.addView(btn, btn_layoutparams);
TextView mytv = new TextView(this);
mytv.setid(101+i);
//set LayoutParams for Button with referenced to the Button(because the Textview Needs to be
of Button)
....
myLayout.addView(mytv, tv-layoutparams);
}
Regarding to the high amount of Views programmatically created, my app starts really slow...
I think it's not because of creating a new View, but because of setting the LayoutParamters each time for the view. I can't find a Workaround because my LayoutParams for the TextView for example Need to reference to the button created before. Due to that i'm not really able to create a XML-layout-file or XML-style-file because i can't reference the tv's layoutparameters anchor in the XML-file to the button which does not exist at the Moment. At least i didn't find a way. I hope somebody got an idea how to appreciable improve the Performance when creating such a amount of views at runtime. Every advise is welcome.
Update regarding answere from rom4ek
The Problem is, that i Need to calculate how much views can i add per row before the Screen-width is fully used. That means i Need second LayoutParams to add the next Button below the first Button from the first row. And i also Need to reference to the img-Button added before in the LayoutParams.. so it's not possible to reference LayoutParams to a Button which doesn't exist before the for-loop.Maybe i completely miss something.. Do you have an idea/solution? Thank you for your respond.
If you're setting the same LayoutParams, what if you move RelativeLayout.Layoutparams btn_layoutparams = new RelativeLayout.LayoutParams.... before the cycle? So you will initialize it one time, and then no need to create new LayoutParams every step.
Related
someone can help me with this?
I didn't understand two things.
one, is that thing:
RelativeLayout.LayoutParams center_ob_l = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.WRAP_CONTENT, RelativeLayout.LayoutParams.WRAP_CONTENT);
what is the meaning of WARP.CONTENT and why should I do this?
second thing, is the "this":
Button log_b = new Button(this);
why should i send "this" in those brackets?
and why at all I would want to create by myself the buttons and things instead of just go to the visual device and throw the things I want to the screen?
This is answer for "this":
Button btn = new Button(this); what is the use of "this" in this context....?
For understanding WRAP_CONTENT read this: https://developer.android.com/reference/android/view/ViewGroup.LayoutParams.html
WRAP_CONTENT means that the relativelayout establish his size fitting his content.
this (java key) refers to current object, whatever it is, the current istance of the class you are coding.
if you don't need to build programmatically your layout, build it with visual editor, when you will need to create the layout programmatically you will understand it by yourself ;)
LayoutParams is used to tell how the view is going to be drawn, you are using this ViewGroup.LayoutParams(int width, int height) where WRAP_CONTENT is the width and height.
check this
https://developer.android.com/reference/android/view/ViewGroup.LayoutParams.html
For Button log_b = new Button(this);
this keyword in java refers to the current class object.
Button(Context context) 'this' is the context you are passing in the constructor
check this
https://developer.android.com/reference/android/widget/Button.html
wrap_content
which means that the view wants to be just big enough to enclose its content (plus padding)
It's roughly the equivalent of setting a Windows Form Control's Autosize property to true
this
is required by the way android works with Context. Specifically when you are passing this you are basically passing the class that encapsulates this statement.
I would like to create a method which returns a RelativeLayout created dynamically. To be clear, let's use this simplified example:
private RelativeLayout createLayout() {
RelativeLayout layout = new RelativeLayout(activity);
RelativeLayout.LayoutParams params = new RelativeLayout.LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.WRAP_CONTENT);
layout.setLayoutParams(params);
TextView tv1 = new TextView(activity);
tv1.setText("Text 1");
TextView tv2 = new TextView(activity);
tv2.setText("Text 2");
TextView tv3 = new TextView(activity);
tv3.setText("Text 3");
layout.addView(tv1);
layout.addView(tv2);
layout.addView(tv3);
return layout;
}
Now I want to position these TextViews relatively to each other. For that I have the idea to use a LayoutParams with the addRule method.
But this method requires an ID, e.g. addRule(RelativeLayout.BELOW, tv2Id). It means that I have to set an ID for each TextViews.
My problem is that the createLayout method will be called several times, so the question is:
Do I have to set different IDs for the TextViews each time the method is called in order to avoid conflicts ? If so, how can I do that ?
Most generally, Is there a better solution for doing it ?
EDIT
The idea behind this is to have a kind of ListView, where each item contains a Map (that can be shown or hidden).
Problem: the Map can't be scroll if it is inside a ListView (at least I did not manage to do that).
For that, I have decided to use a ScrollView and a LinearLayout to copy the behaviour of a ListView. This way the Map can be scrolled correctly and now, all I have to do is to create the items dynamically
ID's don't have to be unique. As you can see from this extract
setId (int id)
Sets the identifier for this view. The identifier does not have to be unique in this view's hierarchy. The identifier should be a positive number.
But like you said, if you want to avoid conflict then you have to find a way to generate unique identifiers for each view.
Frankly, IMO I don't think it matters much the value of the ID. You can use 10, 20, 30. Just make sure you can have access to them anytime you need it, possible using a static final variable.
You asked if there is a better solution, yes there is. The most preferred way is to inflate an xml layout.
Basic question regarding setting the text of a programatically created button. As seen in my code below I've done the basics in terms of creating the button but my button appears as seen in my attached image. Basically the text in the button doesn't appear as expected. Any ideas why?
Note: I've declared button as a public instance variable right above my onCreate() and has been added correctly to my relative layout using addView();
// Create User button
btnUserAdmin = new Button(this);
// Customise the UserAdmin button
btnUserAdmin.setBackgroundColor(Color.BLUE);
btnUserAdmin.setTextSize(13.7f);
btnUserAdmin.setTextColor(Color.parseColor("#FFCC00"));
btnUserAdmin.setText("USER ADMINISTRATION");
btnUserAdmin.setGravity(Gravity.LEFT);
Thanks.
You should specify the dimensions of the button, otherwise the size could be unexpected. For instance
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(
RelativeLayout.LayoutParams.WRAP_CONTENT,
RelativeLayout.LayoutParams.MATCH_PARENT );
btnUserAdmin.setLayoutParams(lp);
also, you can directly set them when you add the buttom
yourRelativeLatout.addView(btnUserAdmin, lp);
Also remember that numeric values for the dimensions (of the bottom or the layout) usually are evil. As you can, use only WRAP_CONTENT and MATCH_PARENT
There are plenty of similar questions asked in SO, but then also, please take time to read my question.
I need to create a UI programmatically that would have multiple ImageView, all positioned at different location of the screen and having their associated click events (its a game app). I found that FrameLayout is appropriate choice, where I can set margins on my own and have it positioned at desired location.
Now, I'm confused whether to have FrameLayout for every single ImageView I create, or to keep single FrameLayout and add all ImageViews within it, but set each imageview at different position.
In either of the case, how can I add FrameLayout, and ImageView within it, programmatically and also set its margin such that it can be placed anywhere on the screen.
Note that my main canvas, which will carry all these ImageViews has background, and the canvas is a LinearLayout set via XML, so my onCreate() already has setContentView(R.layout.game_canvas);, and I'd be using addContentView() to add additional views, but this method too accepts LayoutParams object as it second parameter, so what exactly should I set for this, when I add my FrameLayouts using this method?
My question might be confusing itself, so please let me know if I need to elaborate.
FrameLayouts are designed to only hold one View, so this isn't really the appropriate choice.
Use a RelativeLayout to hold all of your ImageViews. You can position each ImageView by setting the margins in their LayoutParams.
E.g. The following code would place an ImageView at coordinates 50,50:
RelativeLayout imgLayout = new RelativeLayout(this);
ImageView iv = new ImageView(this);
iv.setImageResource(R.drawable.an_image);
RelativeLayout.LayoutParams lp = new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
lp.setMargins(50, 50, 0, 0);
lp.addRule(RelativeLayout.ALIGN_PARENT_LEFT);
lp.addRule(RelativeLayout.ALIGN_PARENT_TOP);
imgLayout.addView(iv, lp);
You can then add this RelativeLayout to your main LinearLayout using its addView() method.
I'm trying to build an android application that features a graphical display drawn within a RelativeLayout. I want to place "+" and "-" buttons next to several of the parameters, which are drawn at various points on the canvas. The positions are free-form don't seem to conform to any of the standard XML layouts.
I know how to create the buttons programmatically, but I don't know how to place them over the canvas where I need them to be. I'm assuming that this would be done in the view thread's doDraw() method, after all the graphics have been drawn, but how?
I struggled with the same problem, and found out great solution.
RelativeLayout rules like "leftOf" or "rightOf" can be implemented programmatically like this:
RelativeLayout container = new RelativeLayout(getApplicationContext());
Button weight = new Button(getApplicationContext());
final int WEIGHT_ID = 0;
weight.setId(WEIGHT_ID);
weight.setText("0.0");
LayoutParams wrapBoth =
new LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
container.addView(weight, wrapBoth);
Button increaseWeight = new Button(getApplicationContext());
increaseWeight.setText("+");
// Note the difference: RelativeLayout.LayoutParams in spite of LayoutParams
RelativeLayout.LayoutParams toBeRightOfWeight =
new RelativeLayout.LayoutParams(LayoutParams.WRAP_CONTENT,LayoutParams.WRAP_CONTENT);
container.addView(parameter,wrapBoth);
// Sweet part
clearAirParams.addRule(RelativeLayout.RIGHT_OF, WEIGHT_ID);
container.addView(increaseWeight, toBeRightOfWeight);
So, in code you can create a 'container' RelativeLayout, then add several Views with unique ID's and, finally, create RelativeLayout.LayoutParams object to achieve sweet-like-sugar methods for alignment, like in XML.