B4J Code Snippet Measure Multiline Text Height

Measuring the length of multiline text is simple in B4A with StringUtils.MeasureMultilineTextHeight and in B4i by setting the width of a multiline Label and calling SizeToFit.

There is no similar method available in B4J. One option is to add a label to an AnchorPane and wait for the layout to be set: https://www.b4x.com/android/forum/threads/measure-text.45750/#post-311358

Another option is to call a non-public API with the following code:
Sub MeasureMultilineTextHeight (Font As Font, Width As Double, Text As String) As Double
   Dim jo As JavaObject = Me
   Return jo.RunMethod("MeasureMultilineTextHeight", Array(Font, Text, Width))
End Sub

#if Java
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import javafx.scene.text.Font;
import javafx.scene.text.TextBoundsType;
public static double MeasureMultilineTextHeight(Font f, String text, double width) throws Exception {
  Method m = Class.forName("com.sun.javafx.scene.control.skin.Utils").getDeclaredMethod("computeTextHeight",
  Font.class, String.class, double.class, TextBoundsType.class);
  return (Double)m.invoke(null, f, text, width, TextBoundsType.LOGICAL_VERTICAL_CENTER);
#End If

Usage example:
Dim height As Double = MeasureMultilineTextHeight(fx.DefaultFont(20), 100, $" jskldf jslkd fjlk wel;fk we;lfk we;lf k
gsdfj lksdf jlksd fjlksd f"$)

Note that if you want to add it to a class then you need to remove the 'static' modifier from the Java code.

As this is a non-public API it might change in the future. It does work with Java 8 and Java 9 so it is probably quite safe to use.
Last edited:


Active Member
Licensed User
Would this also work in B4A? Would remove the dependency on StringUtils :)
Or is there some equivalent code that could be used for MeasureText?