How Sketchware Auto-Generates Custom Variables for Components

Short version: When you add a component (UI or non-UI) in Sketchware, it automatically creates a matching custom variable in the generated Java code so you can use the component in your logic.

What happens when you add a component

Sketchware generates a Java field that matches the component type and name. That field is the custom variable you access from blocks or Java code. This works for both visual UI elements (Buttons, TextViews, WebViews) and non-visual components (MediaPlayer, Timer, Firebase instances, etc.).

Examples

Here are some typical automatic variable declarations Sketchware will create:

// UI component example

private Button button1;

// Non-UI component example

private MediaPlayer mp1;

// WebView example

private WebView webview1;

Auto-generated variable table

Component Type	Example Name	Auto-Generated Variable
Button (UI)	button1	private Button button1;
MediaPlayer (non-UI)	mp1	private MediaPlayer mp1;
WebView (UI)	webview1	private WebView webview1;
RequestNetwork / Firebase	net / auth	private RequestNetwork net; / private FirebaseAuth auth;

What Sketchware also does

• Initializes component variables where appropriate (Sketchware-generated code will include initialization in lifecycle methods).
• Updates names automatically — if you rename the component in the designer, the variable name in generated code updates accordingly.
• Keeps the variable visibility typically private by default (safe practice).

When to add manual custom variables

Add your own custom variables when you need extra state or data that is not a component, for example counters, ArrayLists, configuration objects, or global/static constants.

Sample: Mix of auto-generated and manual variables

public class MainActivity extends Activity {

    // Auto-generated by Sketchware when you add a Button called "sendButton"

    private Button sendButton;

    // Manual custom variables you add

    private int uploadCount = 0;

    private ArrayList imagePaths = new ArrayList<>();

    public static String APP_VERSION = "1.0.0";

}

Tips

1. Use private for component variables unless you intentionally need to access them from other classes.
2. For shared counters or constants use public static or private static final for compile-time constants.
3. If you add a component and it appears missing in code, use the designer to confirm the component id/name and rebuild the project.

Quick checklist

• Drag component to designer → Sketchware adds a variable.
• Rename in designer → variable name updates.
• Need custom logic/state? Add manual custom variables.

Want a ready-made list of manual custom variables (public/private/protected/static) to paste into your Sketchware project? I can generate that as text you can copy into your activity—just say “Yes”.

Written for Sketchware users — practical, copy-paste friendly guidance.