Programmatic Views How to Set Unique Id'S

Programmatic Views how to set unique id's?

Just an addition to the answer of @phantomlimb,

while View.generateViewId() require API Level >= 17,

this tool is compatibe with all API.

according to current API Level,

it decide weather using system API or not.

so you can use ViewIdGenerator.generateViewId() and View.generateViewId() in the
same time and don't worry about getting same id

import java.util.concurrent.atomic.AtomicInteger;

import android.annotation.SuppressLint;
import android.os.Build;
import android.view.View;

/**
 * {@link View#generateViewId()}要求API Level >= 17,而本工具类可兼容所有API Level
 * <p>
 * 自动判断当前API Level,并优先调用{@link View#generateViewId()},即使本工具类与{@link View#generateViewId()}
 * 混用,也能保证生成的Id唯一
 * <p>
 * =============
 * <p>
 * while {@link View#generateViewId()} require API Level >= 17, this tool is compatibe with all API.
 * <p>
 * according to current API Level, it decide weather using system API or not.<br>
 * so you can use {@link ViewIdGenerator#generateViewId()} and {@link View#generateViewId()} in the
 * same time and don't worry about getting same id
 * 
 * @author fantouchx@gmail.com
 */
public class ViewIdGenerator {
    private static final AtomicInteger sNextGeneratedId = new AtomicInteger(1);

    @SuppressLint("NewApi")
    public static int generateViewId() {

        if (Build.VERSION.SDK_INT < 17) {
            for (;;) {
                final int result = sNextGeneratedId.get();
                // aapt-generated IDs have the high byte nonzero; clamp to the range under that.
                int newValue = result + 1;
                if (newValue > 0x00FFFFFF)
                    newValue = 1; // Roll over to 1, not 0.
                if (sNextGeneratedId.compareAndSet(result, newValue)) {
                    return result;
                }
            }
        } else {
            return View.generateViewId();
        }

    }
}

Android: View.setID(int id) programmatically - how to avoid ID conflicts?

According to View documentation

The identifier does not have to be unique in this view's hierarchy. The identifier should be a positive number.

So you can use any positive integer you like, but in this case there can be some views with equivalent id's. If you want to search for some view in hierarchy calling to setTag with some key objects may be handy.

How to assign unique ids to dynamically created Views?

Assign id via code (programmatically)

• Manually set ids using someView.setId(int);
• The int must be positive, but is otherwise arbitrary- it can be whatever you want (keep reading if this is frightful.)
• For example, if creating and numbering several views representing items, you could use their item number.

Normally we do:

To assign id -

for(int i =0 ; i < yourIDcount ; i++){
    yourView.setId(i);
}

To get id -

View.findViewById(yourView.getId());

Also,

API 17 introduced View.generateViewId() which generates a unique ID.

Check:

how-can-i-assign-an-id-to-a-view-programmatically and android-assign-and-retrieve-ids-dynamically.

How to set a unique id to dynamically generated views in Kotlin for Android?

You can generate unique id dynamically for your views using View.generateViewId() function.

For you programmatically created layout or view, you can set id like this

container_overall.id = View.generateViewId()

How can I assign an ID to a view programmatically?

Android id overview

An Android id is an integer commonly used to identify views; this id can be assigned via XML (when possible) and via code (programmatically.) The id is most useful for getting references for XML-defined Views generated by an Inflater (such as by using setContentView.)

Assign id via XML

• Add an attribute of android:id="@+id/somename" to your view.
• When your application is built, the android:id will be assigned a unique int for use in code.
• Reference your android:id's int value in code using "R.id.somename" (effectively a constant.)
• this int can change from build to build so never copy an id from gen/package.name/R.java, just use "R.id.somename".
• (Also, an id assigned to a Preference in XML is not used when the Preference generates its View.)

Assign id via code (programmatically)

• Manually set ids using someView.setId(int);
• The int must be positive, but is otherwise arbitrary- it can be whatever you want (keep reading if this is frightful.)
• For example, if creating and numbering several views representing items, you could use their item number.

Uniqueness of ids

• XML-assigned ids will be unique.
• Code-assigned ids do not have to be unique
• Code-assigned ids can (theoretically) conflict with XML-assigned ids.
• These conflicting ids won't matter if queried correctly (keep reading).

When (and why) conflicting ids don't matter

• findViewById(int) will iterate depth-first recursively through the view hierarchy from the View you specify and return the first View it finds with a matching id.
• As long as there are no code-assigned ids assigned before an XML-defined id in the hierarchy, findViewById(R.id.somename) will always return the XML-defined View so id'd.

Dynamically Creating Views and Assigning IDs

• In layout XML, define an empty ViewGroup with id.
• Such as a LinearLayout with android:id="@+id/placeholder".
• Use code to populate the placeholder ViewGroup with Views.
• If you need or want, assign any ids that are convenient to each view.

• Query these child views using placeholder.findViewById(convenientInt);

• API 17 introduced View.generateViewId() which allows you to generate a unique ID.

If you choose to keep references to your views around, be sure to instantiate them with getApplicationContext() and be sure to set each reference to null in onDestroy. Apparently leaking the Activity (hanging onto it after is is destroyed) is wasteful.. :)

Reserve an XML android:id for use in code

API 17 introduced View.generateViewId() which generates a unique ID. (Thanks to take-chances-make-changes for pointing this out.)*

If your ViewGroup cannot be defined via XML (or you don't want it to be) you can reserve the id via XML to ensure it remains unique:

Here, values/ids.xml defines a custom id:

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <item name="reservedNamedId" type="id"/>
</resources>

Then once the ViewGroup or View has been created, you can attach the custom id

myViewGroup.setId(R.id.reservedNamedId);

Conflicting id example

For clarity by way of obfuscating example, lets examine what happens when there is an id conflict behind the scenes.

layout/mylayout.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
    <LinearLayout
        android:id="@+id/placeholder"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal" >
</LinearLayout>

To simulate a conflict, lets say our latest build assigned R.id.placeholder(@+id/placeholder) an int value of 12..

Next, MyActivity.java defines some adds views programmatically (via code):

int placeholderId = R.id.placeholder; // placeholderId==12
// returns *placeholder* which has id==12:
ViewGroup placeholder = (ViewGroup)this.findViewById(placeholderId);
for (int i=0; i<20; i++){
    TextView tv = new TextView(this.getApplicationContext());
    // One new TextView will also be assigned an id==12:
    tv.setId(i);
    placeholder.addView(tv);
}

So placeholder and one of our new TextViews both have an id of 12! But this isn't really a problem if we query placeholder's child views:

// Will return a generated TextView:
 placeholder.findViewById(12);

// Whereas this will return the ViewGroup *placeholder*;
// as long as its R.id remains 12: 
Activity.this.findViewById(12);

*Not so bad

Android - Set my own unique integer id (not in resources) to many views created programmatically

As you are creating RadioGroups and RadioButtons from java, I suggest to create a map and use radiobutton reference as key and instance-color combination as value. assign a single checkChangedListener to all your radioButtons and process the event as follows

    @Override
     public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {

          colorInstanceCombo = map.get(buttonView);
          //use colorInstanceCombo to do your work    
     }

assigning ids dynamically can cause problems as id is an integer and your assigned ids may cause conflict with system assigned ids to other components.

android - set ID to the view programmatically

According to the API it's not forbidden or deprecated. Here is the best way of using it.

1. Create res/values/ids.xml and define

   <?xml version="1.0" encoding="utf-8"?>
   <resources>
           <item type="id" name="button1" />
           <item type="id" name="button2" />
   </resources>
   

2. once you have that, you can than use setId

   button1.setId(R.id.button1);
   button2.setId(R.id.button2);
   

Dynamically set id of a view

You can just use the View.setId(int) for this. According to documentation id need not to be unique in a tree heirarchy, you can use any (positive) Integer for the Views you add programmatically.

Doc says

The identifier does not have to be unique in this view's hierarchy. The identifier should be a positive number.

if you want some other info attached with the View you can tag objects to view using setTag(), and look by findViewWithTag("obj");

see more about creating ids here https://stackoverflow.com/a/13241629/5235032

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