I use for determine the space between the first two fingers Android SDK 23 marshmallow
private float spacing(WrapMotionEvent event) {
// ...
float x = event.getX(0) - event.getX(1);
float y = event.getY(0) - event.getY(1);
return (Float)Math.sqrt (x * x + y * y);
}
warning message
Error:(415, 32) error: incompatible types: double cannot be converted to Float

Math.sqrt returns a double, even if the input is float.
You can't convert double to Float (the wrapper type) other than explicitly going via float (the primitive type)... but that's okay, because you don't actually want Float. The return type of your method is float, so just cast to that instead:
return (float) Math.sqrt(x * x + y * y);
If the return type of your method had been Float, you could still use the same line of code, and let the compiler add auto-boxing from float to Float.
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