Android Studio 下拉框Spinner实例

左手的ㄟ右手 2023-07-20 05:56 170阅读 0赞

***[点此查看全部文字教程、视频教程、源代码][Link 1]***

### 本文目录 ###

*  1. 功能
 *  2. 显示
 *  3. 动态设置选项
 *  4. 获取选中项
 *  5. 监听下拉框选中项

# 1. 功能 #

下拉框相当常见了，例如选择省、市、县；例如选择部门；选择员工。用处一般是多选一。

# 2. 显示 #

下拉框一般有两种形式，一种是下拉显示可选项，一种是弹窗显示可选项。通过调整参数spinnerMode，dropdown/dialog分别代表两种下拉框。

注意下拉框的数据需要从资源中关联过来，资源文件`res/values/arrays.xml`代码如下：

<?xml version="1.0" encoding="utf-8"?>
    <resources>
        <string-array name="gradeArray">
            <item>初一</item>
            <item>初二</item>
            <item>初三</item>
        </string-array>
    </resources>

Android布局文件如下：

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:padding="4dp">
    
        <Spinner
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:entries="@array/gradeArray"
            android:spinnerMode="dropdown"></Spinner>
    
        <Spinner
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:entries="@array/gradeArray"
            android:spinnerMode="dialog"></Spinner>
    
        <Button
            android:id="@+id/buttonOk"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="确认" />
    </LinearLayout>

效果如下：  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvc2hpc2FuZ3Nhbmc_size_16_color_FFFFFF_t_70_pic_center]  
![在这里插入图片描述][watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvc2hpc2FuZ3Nhbmc_size_16_color_FFFFFF_t_70_pic_center 1]

# 3. 动态设置选项 #

可以利用数组适配器`ArrayAdapter`动态设置下来框的选项，布局文件修改为:

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        android:padding="4dp">
        <Spinner
            android:id="@+id/spinnerGrade"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:spinnerMode="dropdown"></Spinner>
        <Button
            android:id="@+id/buttonOk"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:text="确认" />
    </LinearLayout>

代码部分修改为：

public class MainActivity extends AppCompatActivity {
        
        @Override
        protected void onCreate(Bundle savedInstanceState) {
        
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            Spinner spinnerGrade=findViewById(R.id.spinnerGrade);
            //内容数组
            String[] gradeArray={
        "初一","初二","初三","初四"};
            //数组适配器
            ArrayAdapter<String> gradeAdapter=new ArrayAdapter<>(this,R.layout.support_simple_spinner_dropdown_item,gradeArray);
            spinnerGrade.setAdapter(gradeAdapter);
            //设置默认选中项
            spinnerGrade.setSelection(0);
        }
    }

# 4. 获取选中项 #

点击确认后获取选中项，并显示选中项内容。

public class MainActivity extends AppCompatActivity {
        
        //内容数组
        String[] gradeArray={
        "初一","初二","初三","初四"};
        @Override
        protected void onCreate(Bundle savedInstanceState) {
        
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            Spinner spinnerGrade=findViewById(R.id.spinnerGrade);
            //数组适配器
            ArrayAdapter<String> gradeAdapter=new ArrayAdapter<>(this,R.layout.support_simple_spinner_dropdown_item,gradeArray);
            spinnerGrade.setAdapter(gradeAdapter);
            //设置默认选中项
            spinnerGrade.setSelection(0);
            //获取按钮
            Button buttonOk = findViewById(R.id.buttonOk);
            //设置按钮点击监听器
            buttonOk.setOnClickListener(new MyOnClickListener());
        }
        //定义按钮点击监听器
        class MyOnClickListener implements View.OnClickListener {
        
            //按钮点击
            @Override
            public void onClick(View view) {
        
                if (view.getId() == R.id.buttonOk) {
        //被点击的是确认按钮
                    //获取选中项
                    Spinner spinnerGrade=findViewById(R.id.spinnerGrade);
                    //显示提示框
                    Toast.makeText(MainActivity.this, gradeArray[spinnerGrade.getSelectedItemPosition()] , Toast.LENGTH_SHORT).show();
                }
            }
        }
    }

# 5. 监听下拉框选中项 #

当下拉框选中项发生改变时，弹窗显示新项目，代码如下：

public class MainActivity extends AppCompatActivity {
        
        //内容数组
        String[] gradeArray={
        "初一","初二","初三","初四"};
        @Override
        protected void onCreate(Bundle savedInstanceState) {
        
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
            Spinner spinnerGrade=findViewById(R.id.spinnerGrade);
            //数组适配器
            ArrayAdapter<String> gradeAdapter=new ArrayAdapter<>(this,R.layout.support_simple_spinner_dropdown_item,gradeArray);
            spinnerGrade.setAdapter(gradeAdapter);
            //设置默认选中项
            spinnerGrade.setSelection(0);
            //获取按钮
            Button buttonOk = findViewById(R.id.buttonOk);
            //设置按钮点击监听器
            buttonOk.setOnClickListener(new MyOnClickListener());
    
            spinnerGrade.setOnItemSelectedListener(new MyOnItemSelectedListener());
        }
    
        //定义按钮点击监听器
        class MyOnClickListener implements View.OnClickListener {
        
            //按钮点击
            @Override
            public void onClick(View view) {
        
                if (view.getId() == R.id.buttonOk) {
        //被点击的是确认按钮
                    //获取选中项
                    Spinner spinnerGrade=findViewById(R.id.spinnerGrade);
                    //显示提示框
                    Toast.makeText(MainActivity.this, gradeArray[spinnerGrade.getSelectedItemPosition()] , Toast.LENGTH_SHORT).show();
                }
            }
        }
    
        class MyOnItemSelectedListener implements AdapterView.OnItemSelectedListener {
        
            //选择
            @Override
            public void onItemSelected(AdapterView<?> adapterView, View view, int i, long l) {
        
                Toast.makeText(MainActivity.this, gradeArray[i], Toast.LENGTH_SHORT).show();
            }
            //未选择
            @Override
            public void onNothingSelected(AdapterView<?> adapterView) {
        
            }
        }
    }

[Link 1]: https://studyingpanda.blog.csdn.net/article/details/105329926
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvc2hpc2FuZ3Nhbmc_size_16_color_FFFFFF_t_70_pic_center]: /images/20230528/765dff32f32a4d2fb3b2b77791292135.png
[watermark_type_ZmFuZ3poZW5naGVpdGk_shadow_10_text_aHR0cHM6Ly9ibG9nLmNzZG4ubmV0L3dvc2hpc2FuZ3Nhbmc_size_16_color_FFFFFF_t_70_pic_center 1]: /images/20230528/c004a71e49a646dd8014dc347cb8cc70.png