ConstraintLayout: Adding components programmatically.

Step by step adding a component to ConstraintLayout.

Programmatically adding components to ConstraintLayout

What should happen:

Perform step by step:

Step 1: Project creation

Сreate EmptyProject with root ConstraintLayout (id = constraint_layout):

EmptyProject | root ConstraintLayout

Step 2: Component creation

In folder app -> res -> layout create a file button (tools: works only for preview), and in this file create a button:

Path | Button | Preview

Step 3: The concept of programmatically adding components to the ConstraintLayout

Explanation by lines of code:

13. binding — To get a layout containing ConstraintLayout.

Step 4: Add component onClick

Add View.OnClickListener, create a listener initialization method and add it to onClick:

OnClickListener | initListener | call initListener
Add Button
onClick
Application

Step 5: Adding a component when clicking on an existing component

activiti_main | preview
btn | onClickListener
Application

Step 6: Solving the problem of losing restrictions by parent components

SOLUTION — components will be added not to the parent ConstreintLayout but to the external:

In folder app -> res -> layout create a file constraint_layout:

Path | constraint_layout
constraint_layout | activity_main
before | after
Application

Step 7: Attaching a listener to external components

In activity_main add TextView:

TextView | preview
Button | preview
Increment
before | after
Application

Conclusion:

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