最优解为:

    public String[] items= new String[]{"item1","item2","item3"};
    // here you can use array or list 
    ArrayAdapter adapter= new ArrayAdapter(Your_Context, R.layout.support_simple_spinner_dropdown_item, items);
    final Spinner itemsSpinner= (Spinner) findViewById(R.id.itemSpinner);
itemsSpinner.setAdapter(adapter);

若要自动获取该项的位置，请添加以下语句

itemsSpinner.setSelection(itemsSpinner.getPosition("item2"));

大多数时候spinner.setSelection(i);//i是0到(size-1)适配器的大小 是行不通的。如果你调用spinner.setSelection(i);

这取决于你的逻辑。

如果视图是完全加载的，你想从接口调用它，我建议你调用

spinner.setAdapter(spinner_no_of_hospitals.getAdapter());
spinner.setSelection(i); // i is 0 or within adapter size

或者，如果您想在活动/片段生命周期之间进行更改，请像这样调用

spinner.post(new Runnable() {
  @Override public void run() {
    spinner.setSelection(i);
  }
});

为什么不使用数据库中的值并将它们存储在数组列表中，然后使用:

yourSpinner.setSelection(yourArrayList.indexOf("Category 1"));

这在本页其他地方的评论中有说明，但我认为把它拉出来作为一个答案是有用的:

当使用适配器时，我发现spinnerObject.setSelection(INDEX_OF_CATEGORY2)需要发生在setAdapter调用之后;否则，第一项总是初始选择。

// spinner setup...
spinnerObject.setAdapter(myAdapter);
spinnerObject.setSelection(INDEX_OF_CATEGORY2);

这可以通过检查setAdapter的AbsSpinner代码来确认。

Some explanation (at least for Fragments - never tried with pure Activity). Hope it helps someone to understand Android better. Most popular answer by Arun George is correct but don't work in some cases. The answer by Marco HC uses Runnable wich is a last resort due to additional CPU load. The answer is - you should simply choose correct place to call to setSelection(), for example it works for me: @Override public void onResume() { super.onResume(); yourSpinner.setSelection(pos); } But it won't work in onCreateView(). I suspect that is the reason for the interest to this topic. The secret is that with Android you can't do anything you want in any method - oops:( - components may just not be ready. As another example - you can't scroll ScrollView neither in onCreateView() nor in onResume() (see the answer here)

在Kotlin中，我使用lambda找到了一个简单的解决方案:

spinnerObjec.post {spinnerObjec.setSelection(yourIndex)}