我该如何将ArrayList<String>对象转换为String[]Java中的数组?
你可以为每个选择创建一个选项元素,appendChild复制元素,所以第二个append从第一个元素开始
var select = document.getElementById("selectNumber");
var select2 = document.getElementById("selectNumber2");
var options = ["1", "2", "3", "4", "5"];
for (var i = 0; i < options.length; i++) {
var opt = options[i];
var el = document.createElement("option");
el.textContent = opt;
el.value = opt;
var el1 = document.createElement("option");
el1.textContent = opt;
el1.value = opt;
select.appendChild(el1);
select2.appendChild(el);
}
<select id="selectNumber">
<option>Choose a number</option>
</select>
<select id="selectNumber2">
<option>Choose a number</option>
</select>
不要对两个控件使用相同的元素。先复制
var select = document.getElementById("selectNumber");
var select2 = document.getElementById("selectNumber2");
var options = ["1", "2", "3", "4", "5"];
for (var i = 0; i < options.length; i++) {
var opt = options[i];
var el = document.createElement("option");
el.textContent = opt;
el.value = opt;
select.appendChild(el);
select2.appendChild(el.cloneNode(true));
}
<select id="selectNumber">
<option>Choose a number</option>
</select>
<select id="selectNumber2">
<option>Choose a number</option>
</select>