java - 如何获取用户在相关微调器上选择的数据？

Question

我想做什么

我想获取用户在相关微调器上选择的数据。

在我当前的代码中，成功从第一个旋转器获取数据，但无法从第二个旋转器获取数据。

问题

我应该如何修复我的代码以获取用户选择的适当数据？

1. 在本例中，第二个 textView 应该是 BMW，但它是 Audi，它是第二个旋转器的第一个候选者。

第一个 textView 根据用户的选择而更改。在本例中，它从电机更改为移动，但同样，第二个 textView 仍保留为第二个旋转器的第一个候选。

当前代码

MainActivity.kt

package com.example.spinner

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.Menu
import android.view.MenuItem
import android.app.Activity
import android.content.Intent
import android.util.Log
import android.view.View
import android.widget.AdapterView
import android.widget.Spinner
import android.widget.ArrayAdapter
import kotlinx.android.synthetic.main.activity_main.*
import android.widget.AdapterView.OnItemSelectedListener
import android.widget.Toast

class MainActivity : AppCompatActivity(), AdapterView.OnItemSelectedListener {

    var spinner1: Spinner? = null
    var spinner2: Spinner? = null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        spinner1 = findViewById(R.id.spinner1) as Spinner
        spinner2 = findViewById(R.id.spinner2) as Spinner
        val adapter1 = ArrayAdapter.createFromResource(
            this,
            R.array.array1, android.R.layout.simple_spinner_item
        )
        spinner1?.setAdapter(adapter1)
        spinner1?.setOnItemSelectedListener(this)
    }
    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        // Inflate the main; this adds items to the action bar if it is present.
        menuInflater.inflate(R.menu.main, menu)
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        val id = item.getItemId()
        return if (id == R.id.action_settings) {
            true
        } else super.onOptionsItemSelected(item)
    }

    override fun onItemSelected(
        parent: AdapterView<*>, view: View, position: Int,
        id: Long
    ) {
        if (spinner1?.getSelectedItem() == "mobile") {
            Toast.makeText(
                applicationContext, "Mobil dipilih",
                Toast.LENGTH_SHORT
            ).show()

            val adapter2 = ArrayAdapter.createFromResource(
                this,
                R.array.mobile_array, android.R.layout.simple_spinner_item
            )
            spinner2?.setAdapter(adapter2)
            spinner2?.setOnItemSelectedListener(this)

        } else {
            val adapter2 = ArrayAdapter.createFromResource(
                this,
                R.array.motor_array, android.R.layout.simple_spinner_item
            )
            spinner2?.setAdapter(adapter2)
            spinner2?.setOnItemSelectedListener(this)

        }


        // here I try to put the selected contents to variables
        val spinner1_content = spinner1?.getSelectedItem() as String
        textView1.text = spinner1_content
        val spinner2_content = spinner2?.getSelectedItem() as String
        textView2.text = spinner2_content


    }


    override fun onNothingSelected(parent: AdapterView<*>?) {

    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    tools:context="com.example.stackspinner.MainActivity" >

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

    <Spinner
        android:id="@+id/spinner2"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_below="@+id/spinner1" />


    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:gravity="center_horizontal"
        android:orientation="vertical">

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#00f"
        android:layout_marginTop="100dp"
        android:textSize="40sp" />

    <TextView
        android:id="@+id/textView2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:textColor="#00f"
        android:layout_marginTop="100dp"
        android:textSize="40sp" />

    </LinearLayout>

</RelativeLayout>

字符串.xml

<resources>

    <string name="app_name">Application Name</string>
    <string name="hello_world">Hello world!</string>
    <string name="action_settings">Settings</string>

    <string-array name="array1">
        <item>mobile</item>
        <item>motor</item>
    </string-array>
    <string-array name="mobile_array">
        <item>Android</item>
        <item>blackberry</item>
        <item>apple</item>
    </string-array>
    <string-array name="motor_array">
        <item>Audi</item>
        <item>BMW</item>
        <item>unicorn</item>
    </string-array>
</resources>

听到答案后的当前代码

MainActivity.kt

package com.example.spinner

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.Menu
import android.view.MenuItem
import android.app.Activity
import android.content.Intent
import android.util.Log
import android.view.View
import android.widget.AdapterView
import android.widget.Spinner
import android.widget.ArrayAdapter
import kotlinx.android.synthetic.main.activity_main.*
import android.widget.AdapterView.OnItemSelectedListener
import android.widget.Toast

class MainActivity : AppCompatActivity(), AdapterView.OnItemSelectedListener {

    var spinner1: Spinner? = null
    var spinner2: Spinner? = null
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        spinner1 = findViewById(R.id.spinner1) as Spinner
        spinner2 = findViewById(R.id.spinner2) as Spinner
        val adapter1 = ArrayAdapter.createFromResource(
            this,
            R.array.array1, android.R.layout.simple_spinner_item
        )
        spinner1?.setAdapter(adapter1)
        spinner1?.setOnItemSelectedListener(this)

        val adapter2 = ArrayAdapter.createFromResource(
            this,
            R.array.array1, android.R.layout.simple_spinner_item
        )
        spinner2?.setAdapter(adapter2)
        spinner2?.setOnItemSelectedListener(this)
    }
    override fun onCreateOptionsMenu(menu: Menu): Boolean {
        // Inflate the main; this adds items to the action bar if it is present.
        menuInflater.inflate(R.menu.main, menu)
        return true
    }

    override fun onOptionsItemSelected(item: MenuItem): Boolean {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        val id = item.getItemId()
        return if (id == R.id.action_settings) {
            true
        } else super.onOptionsItemSelected(item)
    }

    override fun onItemSelected(
        parent: AdapterView<*>, view: View, position: Int,
        id: Long
    ) {
        if (spinner1?.getSelectedItem() == "mobile") {
            Toast.makeText(
                applicationContext, "Mobil dipilih",
                Toast.LENGTH_SHORT
            ).show()

            val adapter2 = ArrayAdapter.createFromResource(
                this,
                R.array.mobile_array, android.R.layout.simple_spinner_item
            )
            spinner2?.setAdapter(adapter2)

        } else {
            val adapter2 = ArrayAdapter.createFromResource(
                this,
                R.array.motor_array, android.R.layout.simple_spinner_item
            )
            spinner2?.setAdapter(adapter2)

        }


        // here I try to put the selected contents to variables
        val spinner1_content = spinner1?.getSelectedItem() as String
        textView1.text = spinner1_content
        val spinner2_content = spinner2?.getSelectedItem() as String
        textView2.text = spinner2_content


    }


    override fun onNothingSelected(parent: AdapterView<*>?) {

    }
}

Answer 1

请注意，每次您选择移动设备(或电机)时，您都会重新创建旋转器2。您应该为每个微调器使用不同的监听器:

spinner1.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
            override fun onNothingSelected(parent: AdapterView<*>?) {

            }

            override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
              //your spinner1 listener code
            }

        }

spinner2.dothesame...

我把整个 onCreate 放在一起以便更好地理解:

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_main)
    spinner1 = findViewById(R.id.spinner1) as Spinner
    spinner2 = findViewById(R.id.spinner2) as Spinner
    textView1 = findViewById(R.id.textView1) as TextView
    textView2 = findViewById(R.id.textView2) as TextView

    val adapter1 = ArrayAdapter.createFromResource(
            this,
            R.array.array1, android.R.layout.simple_spinner_item
    )
    spinner1?.setAdapter(adapter1)
    spinner1?.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
        override fun onNothingSelected(parent: AdapterView<*>?) {

        }

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


            var spinner2Adapter: ArrayAdapter<CharSequence>? = null
            //select the right adapter for de Spinner2
            if (spinner1?.getSelectedItem() == "mobile") {
                spinner2Adapter = ArrayAdapter.createFromResource(
                        applicationContext,
                        R.array.mobile_array, android.R.layout.simple_spinner_item
                )
            } else {
                spinner2Adapter = ArrayAdapter.createFromResource(
                        applicationContext,
                        R.array.motor_array, android.R.layout.simple_spinner_item
                )
            }
            //set the adapter and the listener for spinner2
            spinner2?.setAdapter(spinner2Adapter)
            spinner2?.onItemSelectedListener = object : AdapterView.OnItemSelectedListener {
                override fun onNothingSelected(parent: AdapterView<*>?) {

                }

                override fun onItemSelected(parent: AdapterView<*>?, view: View?, position: Int, id: Long) {
                    val spinner2_content = spinner2?.getSelectedItem() as String
                    textView2?.text = spinner2_content

                }
            }


            // here I try to put the selected contents to variables
            val spinner1_content = spinner1?.getSelectedItem() as String
            textView1?.text = spinner1_content
        }

    }
}