android - 如何在 kotlin 的设置活动（首选项）中使用监听器

Question

我没有 java/kotlin/android 背景，并且已经尝试学习了一个星期。我卡在 Settings Activity Listeners

我使用 New > Activity > Settings Activity 创建了一个 Settings Activity，并添加了一个 SeekBar

但无论我尝试了什么，我都无法使 println("triggered") 部分工作

我做错了什么？解释的时候别忘了我是新手

谢谢

PS：API 级别为 21

SettingsActivity.kt

import android.os.Bundle
import android.text.InputType
import android.view.inputmethod.EditorInfo
import android.widget.EditText
import android.widget.SeekBar
import androidx.appcompat.app.AppCompatActivity
import androidx.preference.EditTextPreference
import androidx.preference.PreferenceFragmentCompat


class SettingsActivity2 : AppCompatActivity(), SeekBar.OnSeekBarChangeListener, EditTextPreference.OnBindEditTextListener {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.settings_activity)
        if (savedInstanceState == null) {
            supportFragmentManager
                .beginTransaction()
                .replace(R.id.settings, SettingsFragment())
                .commit()
        }
        supportActionBar?.setDisplayHomeAsUpEnabled(true)
    }

    class SettingsFragment : PreferenceFragmentCompat() {
        override fun onCreatePreferences(savedInstanceState: Bundle?, rootKey: String?) {
            setPreferencesFromResource(R.xml.root_preferences, rootKey)
        }
    }

    override fun onProgressChanged(seekBar: SeekBar?, progress: Int, fromUser: Boolean) {
        println("triggered1")
    }

    override fun onStartTrackingTouch(seekBar: SeekBar?) {
        println("triggered2")
    }

    override fun onStopTrackingTouch(seekBar: SeekBar?) {
        println("triggered3")
    }

    override fun onBindEditText(editText: EditText) {
        println("triggered4")
    }
}

root_preferences.xml

<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <PreferenceCategory app:title="@string/messages_header">

        <EditTextPreference
            app:key="signature"
            app:title="@string/signature_title"
            app:useSimpleSummaryProvider="true" />

        <ListPreference
            app:defaultValue="reply"
            app:entries="@array/reply_entries"
            app:entryValues="@array/reply_values"
            app:key="reply"
            app:title="@string/reply_title"
            app:useSimpleSummaryProvider="true" />
        <SeekBarPreference
            android:key="seekbar_preference"
            android:title="Brightness"
            android:summary="@string/value_percentage"
            android:progress="0"
            app:showSeekBarValue="true" />

    </PreferenceCategory>

    <PreferenceCategory app:title="@string/sync_header">

        <SwitchPreferenceCompat
            app:key="sync"
            app:title="@string/sync_title" />

        <SwitchPreferenceCompat
            app:dependency="sync"
            app:key="attachment"
            app:summaryOff="@string/attachment_summary_off"
            app:summaryOn="@string/attachment_summary_on"
            app:title="@string/attachment_title" />

    </PreferenceCategory>

</PreferenceScreen>

Answer 1

你必须使用OnPreferenceChangeListener

例子

val seekbarPreference: SeekBarPreference? = findPreference("seekbar_preference")
seekbarPreference!!.onPreferenceChangeListener =
    Preference.OnPreferenceChangeListener { preference, newValue ->
         println("triggered1")
        true
    }