Android 中的时间选择器对话框

Android TimePicker是一个用户界面控件，用于选择 24 小时制或 AM/PM 模式的时间。它用于确保用户在我们的应用程序中选择当天的有效时间。时间选择器界面基本上有两种模式，一种是在 XML 布局下，另一种是对话框。在本次讨论中，演示了如何在 android 中实现 TimePicker Dialog。 XML 布局中的 TimePicker 参考 Kotlin 中的 TimePicker。查看下图以了解讨论的概况。

在 Android 应用中实现时间选择器对话框的步骤

第 1 步：创建一个空的活动项目

创建一个空的活动 Android Studio 项目并选择Kotlin作为编程语言。安卓 |如何在 Android Studio 中创建/启动新项目？

步骤 2：使用 activity_main.xml 文件

应用程序的主布局包含一个按钮和 TextView 来预览选择的时间。要实现相同的布局，请调用activity_main.xml文件中的以下代码。

输出界面：

在开始实现 TimePicker 对话框之前，了解对话框结构很重要

第 3 步：使用 MainActivity.kt 文件

在 MainActivity.kt 文件中，TimePickerDialog 的实例有 5 个参数。

TimePickerDialog(Context, TimePickerDialogListener, DefaultHourOfDialog(Int), DefaultMinuteOfDialog(Int), is24HourView(boolean))

要实现 TimePicker 对话框，请调用以下代码。

科特林

import android.app.TimePickerDialog
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Button
import android.widget.TextView
import android.widget.TimePicker
  
class MainActivity : AppCompatActivity() {
  
    lateinit var previewSelectedTimeTextView: TextView
  
    // listener which is triggered when the
      // time is picked from the time picker dialog
    private val timePickerDialogListener: TimePickerDialog.OnTimeSetListener =
        object : TimePickerDialog.OnTimeSetListener {
            override fun onTimeSet(view: TimePicker?, hourOfDay: Int, minute: Int) {
  
                // logic to properly handle 
                  // the picked timings by user
                val formattedTime: String = when {
                    hourOfDay == 0 -> {
                        if (minute < 10) {
                            "${hourOfDay + 12}:0${minute} am"
                        } else {
                            "${hourOfDay + 12}:${minute} am"
                        }
                    }
                    hourOfDay > 12 -> {
                        if (minute < 10) {
                            "${hourOfDay - 12}:0${minute} pm"
                        } else {
                            "${hourOfDay - 12}:${minute} pm"
                        }
                    }
                    hourOfDay == 12 -> {
                        if (minute < 10) {
                            "${hourOfDay}:0${minute} pm"
                        } else {
                            "${hourOfDay}:${minute} pm"
                        }
                    }
                    else -> {
                        if (minute < 10) {
                            "${hourOfDay}:${minute} am"
                        } else {
                            "${hourOfDay}:${minute} am"
                        }
                    }
                }
  
                previewSelectedTimeTextView.text = formattedTime
            }
        }
  
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
  
        // instance of the UI elements
        val buttonPickTime: Button = findViewById(R.id.pick_time_button)
        previewSelectedTimeTextView = findViewById(R.id.preview_picked_time_textView)
  
        // handle the pick time button to
          // open the TimePickerDialog
        buttonPickTime.setOnClickListener {
            val timePicker: TimePickerDialog = TimePickerDialog(
                // pass the Context
                this,
                // listener to perform task
                  // when time is picked
                timePickerDialogListener,
                // default hour when the time picker
                  // dialog is opened
                12,
                // default minute when the time picker
                  // dialog is opened
                10,
                // 24 hours time picker is 
                  // false (varies according to the region)
                false
            )
  
            // then after building the timepicker 
              // dialog show the dialog to user
            timePicker.show()
        }
    }
}

输出：

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