问题

I am using Codename One for a project of mine.

我正在使用Codename One进行我的一个项目。

I have to load the material design icons font.

我需要加载Material Design图标字体。

I know it is included in Codename One fonts but I need to populate the text field writing the original names, like on the web.

我知道它包含在Codename One字体中，但我需要填充文本字段，以原始名称编写，就像在网页上一样。

I have to write, for example, "3d_rotation", instead of a unicode sequence.

我必须编写，例如，“3d_rotation”，而不是Unicode序列。

//font file is in the src folder, it is recognized because a name different from "Material Icons" gives a sort of warning.
//字体文件位于src文件夹中，它被识别出来，因为与“Material Icons”不同的名称会产生一种警告。

Font materialFont = Font.createTrueTypeFont("Material Icons", "materialiconsregular.ttf").
derive(40, Font.STYLE_PLAIN);

textField.getUnselectedStyle().setFont(materialFont);
textField.getSelectedStyle().setFont(materialFont);

String string = "3d_rotation";

textField.setText(string);
System.out.println(string); //OK it's "3d_rotation"
mainLayout.add(textField);
//results in a blank textField with hidden chars like a "3d_rotation" long string.
//导致一个空的文本字段，其中包含像"3d_rotation"一样的隐藏字符。

At runtime I see that the text field is populated with the string and not the glyph, and the string is blank, like white characters, I just can move through them with the cursor.

在运行时，我看到文本字段中填充了字符串而不是字形，并且该字符串是空白的，就像白色字符一样，我只能用光标在其中移动。

What's wrong?
发生了什么问题？

//font file is in the src folder, it is recognized because a name different from "Material Icons" gives a sort of warning.

 Font materialFont =Font.createTrueTypeFont("Material Icons", "materialiconsregular.ttf").
        derive(40, Font.STYLE_PLAIN);

    textField.getUnselectedStyle().setFont(materialFont);
    textField.getSelectedStyle().setFont(materialFont);
    
String string="3d_rotation";

    textField.setText(string);
System.out.println(string); //OK it's "3d_rotation"
mainLayout.add(textField);
//results in a blank textField with hidden chars like a "3d_rotation" long string.