高级控件4：Spinner

Spinner下拉列表组件

主要集合ArrayAdapter、SimpleAdapter以及自定义的Adapter（继承自BaseAdapter）配合使用实现下拉选择或者对话框中选择某一条目。下拉使用的更多，所以，接下来的案例也会重在演示下拉效果。

本次基本就是上代码，前面高级控件中已经详细讲解了适配器参数的含义，也用了多次。

用法1：Spinner+ArrayAdapter（下拉按钮）

spinner_item.xml

<?xml version="1.0" encoding="utf-8"?>
<TextView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:textSize="30sp"/>

注意：不能有布局

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Spinner
        android:id="@+id/spinner"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:spinnerMode="dropdown" />
</LinearLayout>

逻辑文件

package com.yibinu.spinnerdemo;

import androidx.appcompat.app.AppCompatActivity;

import android.database.DataSetObserver;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.SpinnerAdapter;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    Spinner spinner;
    //造数据
    List<String> list;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        spinner = findViewById(R.id.spinner);

        list = new ArrayList<>();
        list.add("====请选择====");
        for (int i = 0; i < 10; i++) {
            list.add("测试文本"+(i+1));
        }

        ArrayAdapter adapter = new ArrayAdapter(this,R.layout.spinner_item,list);
        adapter.setDropDownViewResource(R.layout.spinner_item);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(this);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        TextView textView = (TextView)view;
        Toast.makeText(this, "您选中的是："+textView.getText(), Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {
        spinner.setSelection(0);
    }
}

效果

当选中某一项时，弹出Toast信息，核心方法：setOnItemSelectedListener

用法2：Spinner+SimpleAdapter（下拉按钮）

子项布局：

<?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">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="64dp"
        android:layout_height="64dp"
        android:src="@drawable/ic_launcher_background"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="64dp"
        android:orientation="vertical">
        <TextView
            android:id="@+id/up"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="center_vertical"
            android:text="上"/>
        <TextView
            android:id="@+id/down"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="center_vertical"
            android:text="下"/>
    </LinearLayout>
</LinearLayout>

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".SecondActivity">

    <Spinner
        android:id="@+id/spinner"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:spinnerMode="dropdown" />
</LinearLayout>

逻辑文件：

package com.yibinu.spinnerdemo;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.SimpleAdapter;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class SecondActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    Spinner spinner;
    //造数据
    List<Map<String,String>> list;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        spinner = findViewById(R.id.spinner);

        list = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            Map<String, String> map = new HashMap<>();
            map.put("img",R.drawable.ic_launcher_background+"");
            map.put("up","上部分信息"+(i+1));
            map.put("down","下部分信息"+(i+1));
            list.add(map);
        }

        String[] from = new String[]{"img","up","down"};
        int[] to = new int[]{R.id.imageView,R.id.up,R.id.down};
        SimpleAdapter adapter = new SimpleAdapter(this,list,R.layout.spinner_item2,from,to);
        adapter.setDropDownViewResource(R.layout.spinner_item2);
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(this);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        TextView up = view.findViewById(R.id.up);
        Toast.makeText(this, "您选中的是："+up.getText(), Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {
        spinner.setSelection(0);
    }
}

效果：

用法3：Spinner+自定义适配器（下拉按钮）

创建学生类

package com.yibinu.customdemo;

import android.widget.ImageView;

import androidx.annotation.NonNull;

public class Student {
    private int resid;
    private String name;
    private String grade;

    public Student(int resid, String name, String grade) {
        this.resid = resid;
        this.name = name;
        this.grade = grade;
    }

    public void setName(String name) {
        this.name = name;
    }

    public void setGrade(String grade) {
        this.grade = grade;
    }

    public String getName() {
        return name;
    }

    public String getGrade() {
        return grade;
    }

    public void setResid(int resid) {
        this.resid = resid;
    }

    public int getResid() {
        return resid;
    }

    @Override
    public String toString() {
        return "Student{" +
                "resid=" + resid +
                ", name='" + name + '\'' +
                ", grade='" + grade + '\'' +
                '}';
    }
}

子项布局文件：

<?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">

    <ImageView
        android:id="@+id/imageView"
        android:layout_width="64dp"
        android:layout_height="64dp"
        android:src="@drawable/ic_launcher_background"/>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="64dp"
        android:orientation="vertical">
        <TextView
            android:id="@+id/up"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="center_vertical"
            android:text="上"/>
        <TextView
            android:id="@+id/down"
            android:layout_width="match_parent"
            android:layout_height="0dp"
            android:layout_weight="1"
            android:gravity="center_vertical"
            android:text="下"/>
    </LinearLayout>
</LinearLayout>

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Spinner
        android:id="@+id/spinner"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:spinnerMode="dropdown"/>

</LinearLayout>

自定义适配器

package com.yibinu.customdemo;

import android.content.Context;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;
import java.util.List;

public class MyAdapter extends BaseAdapter {
    private Context context;
    private List<Student> list;
    public MyAdapter(Context context,List<Student> list){
        this.context = context;
        this.list= list;
    }
    @Override
    public int getCount() {
        return list.size();
    }

    @Override
    public Object getItem(int position) {
        return list.get(position);
    }

    @Override
    public long getItemId(int position) {
        return 0;
    }
    //获取一个View
    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Log.i("getView", "getView: ");
        LayoutInflater inflater = LayoutInflater.from(context);
        View view = inflater.inflate(R.layout.spinner_item_3, null);
        ImageView imageView = view.findViewById(R.id.imageView);
        TextView up = view.findViewById(R.id.up);
        TextView down = view.findViewById(R.id.down);
        imageView.setBackgroundResource(list.get(position).getResid());
        up.setText("上部分信息："+(position+1));
        down.setText("上部分信息："+(position+1));
        return view;
    }

}

逻辑文件：

package com.yibinu.customdemo;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

import java.util.ArrayList;
import java.util.List;

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    Spinner spinner;
    int[] resIds = new int[]{R.drawable.a,R.drawable.b,
            R.drawable.e,R.drawable.d, R.drawable.e};
    List<Student> list;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        spinner = findViewById(R.id.spinner);

        list = new ArrayList<>();
        for (int i = 0; i < 10; i++) {
            Student student = new Student(R.drawable.a,"张三"+(i+1),(i+1)+"班");
            list.add(student);
        }

        MyAdapter adapter = new MyAdapter(this,list);
        spinner.setAdapter(adapter);

        spinner.setOnItemSelectedListener(this);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        TextView up = view.findViewById(R.id.up);
        Toast.makeText(this, ""+up.getText(), Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }
}

效果

用法4：Spinner+对话框（对话框）

该种使用方法与前三种最大的区别在于，在逻辑文件中，使用Spinner组件时，需要设置模式为对话框模式，其他操作均相同，本处只写一种方式。

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <Spinner
        android:id="@+id/spinner"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:spinnerMode="dialog"/>
</LinearLayout>

子项布局：

<?xml version="1.0" encoding="utf-8"?>
<TextView
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"/>

逻辑文件

package com.yibinu.dialogspinnerdemo;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.view.View;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.Spinner;
import android.widget.TextView;
import android.widget.Toast;

public class MainActivity extends AppCompatActivity implements AdapterView.OnItemSelectedListener {

    Spinner spinner;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        spinner = findViewById(R.id.spinner);
        ArrayAdapter adapter = new ArrayAdapter(this,R.layout.spinner_item,new String[]{"选项1","选项2","选项3","选项4","选项5"});
        spinner.setAdapter(adapter);
        spinner.setOnItemSelectedListener(this);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
        TextView textView = (TextView)view;
        Toast.makeText(this, "你选择的是："+textView.getText(), Toast.LENGTH_SHORT).show();
    }

    @Override
    public void onNothingSelected(AdapterView<?> parent) {

    }
}

效果：