为了加载ExpandableListView，我可以在android中将Spannable转换为字符串吗？

Question

我创建了一个数组，然后将其加载到HashMap中，然后在ExpandableListView中使用它。但是，我希望用指数的下标和上标来显示部分数据。经过大量的谷歌搜索，上标和下标的解决方案似乎是这样使用的：

text.setText(Html.fromHtml(getString(R.string.acceleration)))

若要在引用中存储的string对象中使用HTML进行格式化，请执行以下操作。但是，这是为了与TextView或按钮一起工作，而不是ListView。问题是我现在意识到这实际上创建了一个Spannable对象，我对它知之甚少，但我知道它不是一个字符串，所以我不能像我希望的那样将它添加到数组中字符串的末尾。我的数组看起来像这样：

constant_common_data = new ListViewItem[]
            {
                    new ListViewItem(R.drawable.star, "Atomic Mass Constant ", "1.660 539 040 e-27", "kg", "0.000 000 020 e-27"),
                    new ListViewItem(R.drawable.star, "Avogadro Constant", "6.022 140 857 e23"," mol^-1", "0.000 000 074 x e23"),
                    new ListViewItem(R.drawable.star, "Boltzmann Constant", "1.380 648 52 e-23", "K^-1", "0.000 000 79 e-23"),
                    new ListViewItem(R.drawable.star, "Conductance Quantum", "7.748 091 7310 e-5", "s","0.000 000 0018 e-5"),
                    new ListViewItem(R.drawable.star, "Electric Constant", "8.854 187 817... e-12", "F m^-1", "(exact)"),

                    new ListViewItem(R.drawable.star, "Electron mass", "9.109 383 56 e-31", "kg", "0.000 000 11 e-31"),
                    new ListViewItem(R.drawable.star, "Electron volt", "1.602 176 6208 e-19"," J", "0.000 000 0098 e-19"),
                    new ListViewItem(R.drawable.star, "Elementary charge ", "1.602 176 6208 e-19", "C", "0.000 000 0098 e-19"),
                    new ListViewItem(R.drawable.star, "Faraday constant ", "96 485.332 89 e-5", "C mol^-1", "0.000 59"),
                    new ListViewItem(R.drawable.star, "Fine-structure constant ", "7.297 352 5664 e-3", "  ", "0.000 000 0017 e-3"),

                    new ListViewItem(R.drawable.star, "Inverse fine-structure constant", "137.035 999 139", "  ", "0.000 000 031"),
                    new ListViewItem(R.drawable.star, "Magnetic constant", "4pi e-7 = 12.566 370 614... e-7"," N A^-2", "(exact)"),
                    new ListViewItem(R.drawable.star, "Magnetic Flux Quantum", "2.067 833 831 e-15", "Wb", "0.000 000 013 e-15"),
                    new ListViewItem(R.drawable.star, "Molar Gas constant", "8.314 4598", "J mol^-1 K^-1", "0.000 0048"),
                    new ListViewItem(R.drawable.star, "Newtonian constant of gravitation ", "6.674 08 e-11", "m^3 kg^-1 s^-2", "0.000 31 e-11"),

                    new ListViewItem(R.drawable.star, "Planck constant", "6.626 070 040 e-34", "J s", "0.000 000 081 e-34"),
                    new ListViewItem(R.drawable.star, "Planck constant over 2 pi", "1.054 571 800 e-34"," J s", "0.000 000 013 e-34"),
                    new ListViewItem(R.drawable.star, "Proton Mass", "1.672 621 898 e-27", "kg", "0.000 000 021 e-27"),
                    new ListViewItem(R.drawable.star, "Proton-Electron Mass Ratio", "1836.152 673 89", "  ", "0.000 000 17"),
                    new ListViewItem(R.drawable.star, "Rydberg constant", "10 973 731.568 508", "m^-1", "0.000 065"),

                    new ListViewItem(R.drawable.star, "Speed of Light in Vacuum", "299 792 458", "m s^-1", "(exact)"),
                    new ListViewItem(R.drawable.star, "Stefan-Boltzmann constant", "5.670 367 e-8", "Wm^-2 K^-4", "0.000 013 e-8"),

                    new ListViewItem(R.drawable.star, "Bohr Radius", "0.529 177 210 67 e-10", "m", "0.000 000 000 12 e-10"),
                    new ListViewItem(R.drawable.star, "Bohr Magneton ", "927.400 9994 e-26"," J T^-1", "0.000 0057 e-26"),
                    new ListViewItem(R.drawable.star, "Josephson constant", "483 597.8525 e9", "Hz V^-1", "0.0030 e9"),
                    new ListViewItem(R.drawable.star, "Von Klitzing constant", "25 812.807 4555", "Ohm", "0.000 0059"),
                    new ListViewItem(R.drawable.star, "Unified Atomic Mass Unit", "1.660 539 040 e-27"+ test , "kg", "0.000 000 020 e-27")
            };}

您可以看到每个ListViewItem都将字符串作为参数，然后在将所有内容加载到列表中之后，我调用如下所示的ListViewItem类的toString方法：

public String toString() {
        return "Value: " + this.value + "\nUnits:  " + this.unit + "\nStandard Uncertainty:  " + this.uncertainty;
    }

以在ExpandableListView的下拉部分中显示。我希望我在ListViewItem中输入的参数能够像这样打印出来，但我也希望它们使用子脚本和超级脚本进行格式化。

我的问题是，有没有一种方法可以将Spannable对象转换为字符串，这样我就可以将它包含在字符串参数中，并让对象在其toString()方法中返回它，仍然具有样式？

谢谢，我很感谢大家的帮助。

Answer 1

经过大量搜索，我找到了以下解决方案：

首先，为了将Spannable转换为String对象，我使用：

 Html.fromHtml(html, Html.FROM_HTML_MODE_LEGACY);

此方法将返回一个Spannable (当然)，在这里您可以使用toString( )方法生成String

String yourString = Html.fromHtml(html, Html.FROM_HTML_MODE_LEGACY).toString();

如果您需要将HTML转换为String (删除标签)，您可以使用以下解决方案：

  public String stripHtml(String html) {
        if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.N) {
           return Html.fromHtml(html, Html.FROM_HTML_MODE_LEGACY);
        } else {
           return Html.fromHtml(html);
        }    
}

Answer 2

如果您将ListViewItem构造函数更改为接受CharSequence参数而不是String，那么您可以使用String或Spanned (.fromHtml()的结果)，因为它们都扩展了CharSequence。

Answer 3

您可以在Html类上使用静态方法toHtml()，尽管它只能处理一些HTML输出，而不能处理任意的事情。此外，您还可以使用SpannableStringBuilder进行更改：

String photoHeading = mContext.getString(R.string.photo_heading);
        SpannableStringBuilder builder = new SpannableStringBuilder(photoHeading);

您还可以有一个ArrayList来保存Spannable，而不是该Spannable的String转换。