如何在 Android 中使用 onItemSelected？

How can I use onItemSelected in Android?

提问by Joseph Little-Indelible

package org.example.mbtiapplication;

import android.os.Bundle;
import android.app.Activity;
import android.view.Menu;
import android.view.View;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemSelectedListener;
import android.widget.ArrayAdapter;
import android.widget.Spinner;

public class MBTITest extends Activity implements OnItemSelectedListener  {

    private Spinner firstSpinner;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_mbtitest);

        Spinner firstSpinner = (Spinner) findViewById(R.id.spinner1);
        // Create an ArrayAdapter using the string array and a default spinner layout
        ArrayAdapter<CharSequence> adapter = ArrayAdapter.createFromResource(this,
                R.array.spinnerarraybool, android.R.layout.simple_spinner_item);
        // Specify the layout to use when the list of choices appears
        adapter.setDropDownViewResource(android.R.layout.simple_spinner_dropdown_item);
        // Apply the adapter to the spinner
        firstSpinner.setAdapter(adapter);
    }

    @Override
    public void onItemSelected(AdapterView<?> parent, View v, int position,
            long id) {
        // TODO Auto-generated method stub

    }

    @Override
    public void onNothingSelected(AdapterView<?> arg0) {
        // TODO Auto-generated method stub      
    } 
}

XML Layout:

XML 布局：

<TableLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <TextView
            android:layout_width="120dp"
            android:layout_height="match_parent"
            android:layout_marginLeft="5dp"
            android:gravity="center_vertical"
            android:text="I like to go out more than staying home." />

        <Spinner
            android:id="@+id/spinner1"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content" />
    </TableRow>

    <TableRow
        android:layout_width="match_parent"
        android:layout_height="wrap_content" >

        <TextView
            android:layout_width="120dp"
            android:layout_height="match_parent"
            android:layout_marginLeft="5dp"
            android:gravity="center_vertical"
            android:textSize="10.5dp"
            android:text="Sensing v Intuition" />

        <Spinner
            android:id="@+id/spinner2"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />
    </TableRow>
</TableLayout>

I'm a new Android programmer and having trouble with using Spinner, i've tried multiple tutorials and still am confused. I'd like to know what my next step is here, as far as I know I have set up my spinner in XML, in Java I have identified that spinner, created an ArrayAdapter for said spinner, and specified some options. I'm not to sure if I have populated the spinner yet or how to manuever with the spinner object. I'd like to be able to use the spinner object to select one of three options and then keep that value inside of the textview inside of the spinner.

我是一名新的 Android 程序员，在使用 Spinner 时遇到问题，我尝试了多个教程，但仍然感到困惑。我想知道我的下一步是什么，据我所知，我已经在 XML 中设置了我的微调器，在 Java 中我已经确定了该微调器，为所述微调器创建了一个 ArrayAdapter，并指定了一些选项。我不确定我是否已经填充了微调器或如何使用微调器对象进行操作。我希望能够使用微调器对象选择三个选项之一，然后将该值保留在微调器内的 textview 内。

回答by bgse

You're almost there. As you can see, the onItemSelectedwill give you a positionparameter, you can use this to retrieve the object from your adapter, as in getItemAtPosition(position).

您快到了。如您所见，onItemSelected将为您提供一个position参数，您可以使用它从您的适配器中检索对象，如getItemAtPosition(position).

Example:

例子：

spinner.setOnItemSelectedListener(this);

...

public void onItemSelected(AdapterView<?> parent, View view, int pos,long id) {
    Toast.makeText(parent.getContext(), 
        "OnItemSelectedListener : " + parent.getItemAtPosition(pos).toString(),
        Toast.LENGTH_SHORT).show();
}

This will put a message on screen, with the selected item printed by its toString() method.

这将在屏幕上显示一条消息，所选项目由其 toString() 方法打印。

回答by Azurespot

If you don't want to implement the listener, you can set it up like this directly where you want it (call on your spinner afteryour adapter has been set):

如果你不想实现监听器，你可以像这样直接在你想要的地方设置它（在你的适配器设置后调用你的微调器）：

spinner.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

                switch (position) {
                    case 0:
                        Toast.makeText(parent.getContext(), "Spinner item 1!", Toast.LENGTH_SHORT).show();
                        break;
                    case 1:
                        Toast.makeText(parent.getContext(), "Spinner item 2!", Toast.LENGTH_SHORT).show();
                        break;
                    case 2:
                        Toast.makeText(parent.getContext(), "Spinner item 3!", Toast.LENGTH_SHORT).show();
                        break;
                }
            }

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

               // sometimes you need nothing here
            }
        });

回答by Jorge Torres

Another thing: When you have more than one spinner in your layout, you have to implement a switch selection in the onItemSlected() method to know which widget was clicked. Something like this:

另一件事：当你的布局中有多个微调器时，你必须在 onItemSlected() 方法中实现一个开关选择来知道哪个小部件被点击。像这样的东西：

@Override
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
    switch (parent.getId()){
        case R.id.sp_alarmSelection:
            //Do something
            Toast.makeText(this, "Alarm Selected: " + parent.getSelectedItem().toString(), Toast.LENGTH_SHORT).show();
            break;
        case R.id.sp_optionSelection:
            //Do another thing 
            Toast.makeText(this, "Option Selected: " + parent.getSelectedItem().toString(), Toast.LENGTH_SHORT).show();
            break;
    }
}

回答by Ilja Popov

For Kotlin and bindings the code is:

对于 Kotlin 和绑定，代码是：

binding.spinner.onItemSelectedListener = object : AdapterView.OnItemSelectedListener{
            override fun onNothingSelected(parent: AdapterView<*>?) {
            }

            override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
            }
        }

回答by Tuan Do

Joseph: spinner.setOnItemSelectedListener(this)should be below Spinner firstSpinner = (Spinner) findViewById(R.id.spinner1);on onCreate

约瑟夫： spinner.setOnItemSelectedListener(this)应低于 Spinner firstSpinner = (Spinner) findViewById(R.id.spinner1);上onCreate

回答by Rohit Sharma

spinner1.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

               //check if spinner2 has a selected item and show the value in edittext

            }

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

               // sometimes you need nothing here
            }
        });

spinner2.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
            @Override
            public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {

               //check if spinner1 has a selected item and show the value in edittext


            }

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

               // sometimes you need nothing here
            }
        });

回答by Said Erraoudy

I think this will benefit you Try this I'm using to change the language in my application

我认为这对你有好处试试这个我用来改变我的应用程序中的语言

String[] districts;
Spinner sp;

......

......

 sp = (Spinner) findViewById(R.id.sp);
         districts = getResources().getStringArray(R.array.lang_array);
         ArrayAdapter<String> adapter = new ArrayAdapter<String>(this, android.R.layout.simple_spinner_item,districts);
         sp.setAdapter(adapter);
         sp.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
              @Override
             public void onItemSelected(AdapterView<?> arg0, View arg1, int position, long arg3) {
                  // TODO Auto-generated method stub
                  int index = arg0.getSelectedItemPosition();
                  Toast.makeText(getBaseContext(), "You select "+districts[index]+" id "+position, Toast.LENGTH_LONG).show();
                  switch(position){
                      case 0:
                          setLocal("fr");
                          //recreate();
                          break;
                      case 1:
                          setLocal("ar");
                          //recreate();
                          break;
                      case 2:
                          setLocal("en");
                          //recreate();
                          break;
                      default: //For all other cases, do this
                          setLocal("en");
                          //recreate();
                          break;
                  }
              }
             @Override
            public void onNothingSelected(AdapterView<?> arg0) {
                   // TODO Auto-generated method stub
                         }
        });

and this is my String Array

这是我的字符串数组

<string-array name="lang_array">
    <item>french</item>
    <item>arabic</item>
    <item>english</item>
</string-array>