你可以这样尝试:

<string name="title"><u><b><i>Your Text</i></b></u></string>

TextView text = (TextView)findViewById(R.layout.textName);
text.setTypeface(null,Typeface.BOLD);

尝试通过java代码设置你的TextView样式

txt1.setTypeface(null,Typeface.BOLD_ITALIC);

在AndroidX中使用简化标签时，请考虑使用HtmlCompat.fromHtml()

String s = "<b>Bolded text</b>, <i>italic text</i>, even <u>underlined</u>!"    
TextView tv = (TextView)findViewById(R.id.THE_TEXTVIEW_ID);
tv.setText(HtmlCompat.fromHtml(s, FROM_HTML_MODE_LEGACY));

你有两个选择:

选项1(只适用于粗体、斜体和下划线):

String s = "<b>Bolded text</b>, <i>italic text</i>, even <u>underlined</u>!"
TextView tv = (TextView)findViewById(R.id.THE_TEXTVIEW_ID);
tv.setText(Html.fromHtml(s));

选项2:

使用可伸缩帆布;它更复杂，但您可以动态修改文本属性(不仅是粗体/斜体，还包括颜色)。

基于样式选择标准，最简单的方法是:

String pre = "", post = "";

if(isBold){
    pre += "<b>"; post += "</b>";
}
if(isItalic){
    pre += "<i>"; post += "</i>";
}
if(isUnderline){
    pre += "<u>"; post += "</u>";
}

textView.setText(Html.fromHtml(pre + editText.getText().toString()+ post));
// you can also use it with EidtText
editText.setText(Html.fromHtml(pre + editText.getText().toString()+ post));