如何创建下拉列表? [英] How to create a drop-down list?

问题描述

如何创建下拉列表?我已经尝试过 ScrollView，但它并不是我所需要的.

How can I create a drop-down list? I've tried a ScrollView but it's not exactly what I need.

推荐答案

简单/优雅/我是怎么做的:

simple / elegant / how I do it:

预览:

XML:

<Spinner
    android:id="@+id/spinner1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@android:drawable/btn_dropdown"
    android:spinnerMode="dropdown"/>

spinnerMode 设置为 dropdown 是 androids 制作下拉菜单的方式.(https://developer.android.com/reference/android/widget/Spinner#attr_android:spinnerMode)

spinnerMode set to dropdown is androids way to make a dropdown. (https://developer.android.com/reference/android/widget/Spinner#attr_android:spinnerMode)

Java:

//get the spinner from the xml.
Spinner dropdown = findViewById(R.id.spinner1);
//create a list of items for the spinner.
String[] items = new String[]{"1", "2", "three"};
//create an adapter to describe how the items are displayed, adapters are used in several places in android.
//There are multiple variations of this, but this is the basic variant.
ArrayAdapter<String> adapter = new ArrayAdapter<>(this, android.R.layout.simple_spinner_dropdown_item, items);
//set the spinners adapter to the previously created one.
dropdown.setAdapter(adapter);

文档:

这是基础知识，但还有更多内容需要通过实验自学.https://developer.android.com/guide/topics/ui/controls/spinner.html

This is the basics but there is more to be self taught with experimentation. https://developer.android.com/guide/topics/ui/controls/spinner.html

1. 您可以将 setOnItemSelectedListener 用于此.(https://developer.android.com/guide/topics/ui/controls/spinner.html#SelectListener)
2. 您可以从 xml 添加字符串列表.(https://developer.android.com/guide/topics/ui/controls/spinner.html#Populate)
3. 此视图有一个 appCompat 版本.(https://developer.android.com/reference/androidx/appcompat/widget/AppCompatSpinner)

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