Typical way to reference android control is something like this:
TextView tv = (TextView)findViewById(R.id.tv);
Where R.id.tv is integer referencing my xml control.
The thing is I would like to make reference using string "R.id.tv". Is that possible?
Let's say I have multiple controls:
tv1,
tv2,
tv3,
tv4,
tv5,
How would I put this into some sort of loop and interate through controls. I am thinking I would use loop counter to reference different controls. How's that to be done? Thanks.
One approach is to put the ids into an array and reference by subscript.
int[] ids = { R.id.tv1, R.id.tv2 /* etc. */ };
for (int i = 0; i < ids.length; ++i) {
TextView tv = (TextView)findViewById(ids[i]);
}
Try next
private int getIdResourceByName(String aString)
{
String packageName = "com.myProject.myPackage"; // set your package name here
int resId = getResources().getIdentifier(aString, "id", packageName);
return resId;
}
...
for (int i = 1; i<=5; i++) {
TextView tv = (TextView) findViewById(getIdResourceByName("tv" + Integer.toString(i)));
...
}
Have a look at this question:
Using findviewbyid with a string in a loop
I don't understand why you'd want to do this, it's pretty ugly, inefficient, and likely to cause maintenance issues and bugs.
Why not use a collection (e.g. ArrayList) to store references to all the controls?
Related
for(int i=1;i<=3;i++)
{
String my_id="Ezequiel_1_"+i;
final TextView modelTextview = (TextView) findViewById(R.id.my_id);
modelTextview.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
the_controller.buttonController(v);
}
});
}
I arranged my ids in the previous manner and I don't want to set the method one by one. Is it possible to iterate like that?
Not directly, because strings aren't ids. There's two ways to do what you want though:
1)Data based
int textViewIds[] = [R.id.Ezequiel_1_1, R.id.Ezequiel_1_2, R.id.Ezequiel_1_3,...]
for(int id: textViewIds) {
TextView tv = (TextView) findViewById(id);
...
}
2)Name based
for(int i=0; i<numView, i++) {
int resourceId = resources.getIdentifier("Ezequiel_1_"+i, "id",
context.getPackageName());
TextView tv = (TextView) findViewById(id);
...
}
I prefer method 1 as it gives you clearer code and protection against off by 1 errors (they won't compile).
I have 16 buttons, whose names are "button1", "button2", and so on. Is there a way I can iterate through them using a for loop, by somehow appending the number value upon each iteration? Something like this:
for(int i = 1; i<17; i++ ){
Button b = (Button)findViewById(R.id.buttoni);
I know I can simply initialize each button in my onCreate() method, but I was just curious if I could do it in a way similar to my example code.
Thank you.
You can use getIdentifier :
for(int i = 1; i<17; i++ ){
int buttonId = getResources().getIdentifier("button"+i, "id", getPackageName());
Button b = (Button)findViewById(buttonId);
//Your stuff with the button
}
You can create an array of Button's and use getIdentifier method that allows you to get an identifier by its name.
final int number = 17;
final Button[] buttons = new Button[number];
final Resources resources = getResources();
for (int i = 0; i < number; i++) {
final String name = "btn" + (i + 1);
final int id = resources.getIdentifier(name, "id", getPackageName());
buttons[i] = (Button) findViewById(id);
}
In case someone is interested how to achive the same result using Java only
The solution above uses Android specific methods (such as getResources, getIdentifier) and can not be used in usual Java, but we can use a reflection and write a method that works like a getIdentifier:
public static int getIdByName(final String name) {
try {
final Field field = R.id.class.getDeclaredField(name);
field.setAccessible(true);
return field.getInt(null);
} catch (Exception ignore) {
return -1;
}
}
And then:
final Button[] buttons = new Button[17];
for (int i = 0; i < buttons.length; i++) {
buttons[i] = (Button) findViewById(getIdByName("btn" + (i + 1)));
}
NOTE:
Instead of optimizing this kind of code you should rethink your layout. If you have 17 buttons on the screen, a ListView is probably the better solution. You can access the items via index and handle onClick events just like with the buttons.
I am making a word game in which each a user has multiple guesses, each one made up of multiple TextViews. So far my code reads:
TextView[] guess1 = new TextView[numTextViews];
guess1[0] = (TextView) findViewById(R.id.Guess1_1);
guess1[1] = (TextView) findViewById(R.id.Guess1_2);
guess1[2] = (TextView) findViewById(R.id.Guess1_3);
guess1[3] = (TextView) findViewById(R.id.Guess1_4);
guess1[4] = (TextView) findViewById(R.id.Guess1_5);
with the xml looking like:
<TextView
android:id="#+id/Guess1_1"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_weight="1"
android:gravity="center"
android:text="#string/guessChar" />...
which repeats with android:id= changing.
I am going to be repeating myself if I type out TextView[] guess2 and all its elements.
What is a better way to go about this?
Would it be better to create all the TextViews programmatically as they are so similar?
This is how you can iterate through your views without the use of ids in repetitive code:
LinearLayout ll = (LinearLayout) findViewById(R.id.layout_containing_textviews);
for (int i = 0; i < ll.getChildCount(); i++) {
if (ll.getChildAt(i).getClass() == TextView.class) {
guess1[i] = (TextView)ll.getChildAt(i);
}
}
Make sure to tweak this in case you have non-TextView views since the i index will not be consecutive in that case. You can use another counter just for the TextViews.
Now if your layout has only TextViews, you don't even need an array. You can use that layout as a container/array the way it's used in the snipped above.
Do you know what is the amount of guesses for each text view?
I would suggest you to use reflection
Class clazz = R.id.class; // get the R class
Field f = clazz.getField("Guess1_" + "1");
int id = f.getInt(null); // pass in null, since field is a static field.
TextView currcell = (TextView) findViewById(id);
in this case it will bring the Guess1_1
for you case:
for (int i =0; i < numTextViews; i++)
{
Class clazz = R.id.class;
Field f = clazz.getField("Guess1_" + Integer.toString(i+1));
int id = f.getInt(null);
guess[i] = (TextView)findViewById(id);
}
but this only bring you the first array of Guess1 you need to convert it to generic code..
so some problems can be occur.. so read it with the xml as you have right now would be the easiest way..
Edit:
If the all textView have the same attributes you can also create it programmatically
LinearLayout view = new LinearLayout(this); // create new linear layout
view.setOrientation(LinearLayout.HORIZONTAL); // optional.. so the
// view will be horizontaly
view.setLayoutParams(new LayoutParams(LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT)); // set the layout
// height and width
for (int i = 0; i < numOf ; i ++)
{
LinearLayout.LayoutParams lp = new LinearLayout.LayoutParams(
LinearLayout.LayoutParams.WRAP_CONTENT,
LinearLayout.LayoutParams.WRAP_CONTENT);
guess[i] = new TextView();
guess[i].setLayoutParams(lp);
guess[i].setID(i+1);
}
You could either create the textViews programmatically (and use inflate if you wish to use some xml too), or you could use the getIdentifier method , for example:
private static final String ID_FORMAT="Guess1_%d";
...
for(int i=0;i<10;++i)
{
String id=String.format(FORMAT,i);
TextView tv = (TextView) findViewById(getResources().getIdentifier(id, "id", getPackageName()));
//...
}
same goes if you wish to do a loop within a loop.
If the layout has a lot of views, I would suggest using an adapterView (listView,gridView,...) instead, and avoid creation of so many views (either programmatically or by xml).
I want to add a LinearLayout wrapped around a TextView and Button programmatically. I want it to take a String array and then using the length of the string array, add that many TextViews each with their own button.
So first:
String [] s = { .... the values ....}
int sL = s.length;
TextView t1 = new TextView (this);
// then somehow create t2, t3... etc. matching the length of the String array.
Is this the best way to do this or is there another way to do this? For some context, it's a quiz app and I've created a list of categories inside resources as values and I'm trying to programmatically get my app to create as many TextViews as there are categories then set each TextView to each category then get each button to take the user to that category of questions.
You are starting it right, just do a for loop and add textviews to your linearlayout.
// You linearlayout in which you want your textview
LinearLayout linearLayout = (LinearLayout) findViewById(R.id.mylayout);
linearLayout.setBackgroundColor(Color.TRANSPARENT);
String [] s = { .... the values ....}
int sL = s.length;
TextView textView = null;
// For later use if you'd like
ArrayList<TextView> tViews = new ArrayList<TextView>();
for (int i = 0; i < sL; i++)
{
textView = new TextView(this);
textView.setText(s[i]);
linearLayout.addView(textView);
tViews.add(textView);
}
There is nothing wrong with this way of doing it. If you want to use these textview later on (set text for them or something) store them in an Array of some kind. Edited code
You can do the following:
for(int i=0;i<s.length;i++){
TextView t=new TextView(this);
t.setText(s[i]);
yourLinearLayout.addView(t);
}
But I really think that using a ListView would be better for performance ;)
I'm making an android application, where there is a view composed of hundreds of buttons, each with a specific callback. Now, I'd like to set these callbacks using a loop, instead of having to write hundreds of lines of code (for each one of the buttons).
My question is: How can I use findViewById without statically having to type in each button id?
Here is what I would like to do:
for(int i=0; i<some_value; i++) {
for(int j=0; j<some_other_value; j++) {
String buttonID = "btn" + i + "-" + j;
buttons[i][j] = ((Button) findViewById(R.id.buttonID));
buttons[i][j].setOnClickListener(this);
}
}
Thanks in advance!
You should use getIdentifier()
for(int i=0; i<some_value; i++) {
for(int j=0; j<some_other_value; j++) {
String buttonID = "btn" + i + "-" + j;
int resID = getResources().getIdentifier(buttonID, "id", getPackageName());
buttons[i][j] = ((Button) findViewById(resID));
buttons[i][j].setOnClickListener(this);
}
}
You can try making an int[] that holds all of your button IDs, and then iterate over that:
int[] buttonIDs = new int[] {R.id.button1ID, R.id.button2ID, R.id.button3ID, ... }
for(int i=0; i<buttonIDs.length; i++) {
Button b = (Button) findViewById(buttonIDs[i]);
b.setOnClickListener(this);
}
Take a look at these answers:
Android and getting a view with id cast as a string
Array of ImageButtons, assign R.view.id from a variable
you can Use tag if you want to access.
in onClick
int i=Integer.parseInt(v.getTag);
But you cant access that button like this.
simply create button programatically
by Button b=new Button(this);
create Custom Button in java code rather in Xml as i shown below
Button bs_text[]= new Button[some_value];
for(int z=0;z<some_value;z++)
{
try
{
bs_text[z] = (Button) new Button(this);
}
catch(ArrayIndexOutOfBoundsException e)
{
Log.d("ArrayIndexOutOfBoundsException",e.toString());
}
}
If your top level view only has those button views as children, you could do
for (int i = 0 ; i < yourView.getChildCount(); i++) {
Button b = (Button) yourView.getChildAt(i);
b.setOnClickListener(xxxx);
}
If there are more views present you'd need to check if the selected one is one of your buttons.
If for some reason you can't use the getIdentifier() function and/or you know the possible id's beforehand, you could use a switch.
int id = 0;
switch(name) {
case "x":
id = R.id.x;
break;
etc.etc.
}
String value = findViewById(id);
To put it simply, here's a function for it
public View findViewByArrayName (String name, int i) {
buttonID = name + Integer.toString(i);
resID = getResources().getIdentifier(buttonID, "id", getPackageName());
return findViewById(resID);
}
Also unlike Python, Java is a compiled language, so it probably makes sense that there aren't any chances for dynamic variable names. Unless achieved through a certain approach like this one.