jfeinstein10/SlidingMenu · error · IllegalStateException

The BehindFadeDegree must be between 0.0f and 1.0f

Error message

The BehindFadeDegree must be between 0.0f and 1.0f

What it means

SlidingMenu's setFadeDegree() validates that the fade amount for the behind view lies in [0.0f, 1.0f]. 0 means no fade and 1 means full fade as the menu slides; anything else would produce undefined rendering, so the library throws IllegalStateException immediately.

Solutions

1. Pass a float clamped to [0.0f, 1.0f], e.g. Math.max(0f, Math.min(1f, value))
2. If using a percentage 0-100, divide by 100f before calling
3. Call inside a try-catch or validate before assigning

Example fix

// before
slidingMenu.setBehindFadeDegree(1.2f);
// after
float fade = 1.2f;
slidingMenu.setBehindFadeDegree(Math.max(0f, Math.min(1f, fade)));

if (degree < 0f || degree > 1f) throw new IllegalArgumentException("fade degree must be in [0,1]: " + degree);
slidingMenu.setBehindFadeDegree(degree);

static boolean isValidFadeDegree(Float d) { return d != null && !d.isNaN() && d >= 0f && d <= 1f; }

try { slidingMenu.setBehindFadeDegree(degree); } catch (IllegalStateException e) { slidingMenu.setBehindFadeDegree(0f); }

When it happens

Trigger: Calling CustomViewBehind.setFadeDegree(float) (usually via SlidingMenu.setBehindFadeDegree) with a negative value or a value greater than 1.0f.

Common situations: Passing a percentage like 50 instead of 0.5f; computing the degree from pixels or dpi values; typo'ing a scale factor (e.g. 1.5f intended as clamped fade).

Understand the failure class

Background: "value must be between 0 and 1" / "out of range" / "must not be negative" errors: fixing range-validation failures across open-source libraries — this error's family across 42 libraries.

Related errors

• slideStyle must be either SLIDING_WINDOW or SLIDING_CONTENT
• SlidingMenu mode must be LEFT, RIGHT, or LEFT_RIGHT
• ScrollScale must be between 0 and 1
• Cannot set both behindOffset and behindWidth for a…
• This SlidingMenu appears to already be attached

AI-assisted analysis of jfeinstein10/SlidingMenu@4254feca3e (2026-09-09). Data as JSON: /api/errors/1702fdd481155af3. Report an issue: GitHub.

Appendix: source

Thrown at library/src/com/jeremyfeinstein/slidingmenu/lib/CustomViewBehind.java:200

	}

	public void setSecondaryShadowDrawable(Drawable shadow) {
		mSecondaryShadowDrawable = shadow;
		invalidate();
	}

	public void setShadowWidth(int width) {
		mShadowWidth = width;
		invalidate();
	}

	public void setFadeEnabled(boolean b) {
		mFadeEnabled = b;
	}

	public void setFadeDegree(float degree) {
		if (degree > 1.0f || degree < 0.0f)
			throw new IllegalStateException("The BehindFadeDegree must be between 0.0f and 1.0f");
		mFadeDegree = degree;
	}

	public int getMenuPage(int page) {
		page = (page > 1) ? 2 : ((page < 1) ? 0 : page);
		if (mMode == SlidingMenu.LEFT && page > 1) {
			return 0;
		} else if (mMode == SlidingMenu.RIGHT && page < 1) {
			return 2;
		} else {
			return page;
		}
	}

	public void scrollBehindTo(View content, int x, int y) {
		int vis = View.VISIBLE;		
		if (mMode == SlidingMenu.LEFT) {
			if (x >= content.getLeft()) vis = View.INVISIBLE;

View on GitHub (pinned to 4254feca3e)