用于浮点数的 android numberpicker

Question

我们应用的用户应该能够调整浮点数。目前，我用所有可能的值填充了一个 ArrayAdapter 并将它附加到一个微调器。

这个解决方案并没有真正达到我们的期望，因为微调框下拉框太高了。有没有更好的办法？我在看 Numberpicker - 但这似乎只适用于整数值。

有什么想法吗？

谢谢！

Answer 1

NumberPicker 不仅适用于整数。甚至您也可以使用 Floats String 等。

请参阅this 并阅读相关内容。

教程：

• http://gafurbabu.wordpress.com/2012/03/29/android-number-picker-dialog/

我很久以前就这样使用过NumberPicker，在这里发帖可能会有用处：

    NumberPicker np;
    String nums[]= {"Select Fraction","1/64","1/32","3/64","1/16","5/64","3/32","7/64","1/8","9/64","5/32","11/64","3/16","13/64","7/32","15/64","1/4","17/64","9/32","19/64","5/16","21/64","11/32","23/64","3/8","25/64","13/32","27/64","7/16","29/64"};

            np = (NumberPicker) findViewById(R.id.np);

            np.setMaxValue(nums.length-1);
            np.setMinValue(0);
            np.setWrapSelectorWheel(false);
            np.setDisplayedValues(nums);
            np.setDescendantFocusability(NumberPicker.FOCUS_BLOCK_DESCENDANTS); 

您可以将ArrayList 设为任何数据类型并分配它。

Answer 2

另一种解决方案是将两个数字字段组合成一个组件。请参阅Money Picker Example。它的优点是您不必为微调器初始化所有可能的双精度值。

您可能还需要使用java.lang.String.format() 函数附加特殊数字格式，如“00”、“0123” 或其他.例如here。

1. 添加双选择器 xml 布局：

   <LinearLayout
     xmlns:android = "http://schemas.android.com/apk/res/android"
     android:layout_width = "fill_parent"
     android:layout_height = "wrap_content"
     android:gravity = "center">
   
     <NumberPicker
       android:id = "@+id/integer_picker"
       android:layout_width = "wrap_content"
       android:layout_height = "wrap_content"
       android:layout_gravity = "center"/>
   
     <TextView
       android:layout_width = "wrap_content"
       android:layout_height = "wrap_content"
       android:layout_gravity = "center"
       android:padding = "5dp"
       android:text = "@string/local_separator"
       android:textSize = "20sp"/>
   
     <NumberPicker
       android:id = "@+id/fraction_picker"
       android:layout_width = "wrap_content"
       android:layout_height = "wrap_content"
       android:layout_gravity = "center"/>
   
     <TextView
       android:layout_width = "wrap_content"
       android:layout_height = "wrap_content"
       android:layout_gravity = "center"
       android:padding = "5dp"
       android:text = "@string/measure_unit_sign"
       android:textSize = "20sp"/>
   
   </LinearLayout>
   

2. 添加自定义 Double Picker 类：

   import android.content.Context;
   import android.view.LayoutInflater;
   import android.widget.NumberPicker;
   
   /**
    * UI component for double (floating point) values. Can be used
    * for money and other measures.
    */
   public class DoublePicker
     extends NumberPicker {
   
     private int decimals;
     private NumberPicker integerPicker;
     private NumberPicker fractionPicker;
   
     public DoublePicker(
       Context context) {
   
       super(
         context);
   
         LayoutInflater
           .from(
             context)
           .inflate(
             R.layout.double_picker,
             this);
   
         integerPicker =
           (NumberPicker) findViewById(
             R.id.integer_picker);
   
         fractionPicker =
           (NumberPicker) findViewById(
             R.id.fraction_picker);
     }
   
     public int getDecimals() {
   
       return decimals;
     }
   
     /**
      * Sets the amount of digits after separator.
      *
      * @param decimals Anount of decimals.
      */
     public void setDecimals(final int decimals) {
   
       this.decimals = decimals;
   
       this.setFormatter(new DoublePicker.Formatter() {
   
         @Override
         public String format(int i) {
   
           return String.format(
             "%." + decimals + "f",
             i);
         }
       });
     }
   
     public void setValue(double value) {
   
       integerPicker.setValue((int) value);
   
       fractionPicker.setValue(
         Integer.valueOf(
           String
             .valueOf(value)
             .split(".")
             [1]));
     }
   }
   

3. 在您的活动 xml 中使用新的 Double Picker 组件：

   <com.example.DoublePicker
     android:id ="@+id/double_picker"
     android:layout_width ="match_parent"
     android:layout_height ="wrap_content" />
   

Answer 3

在 Kotlin 中，您可以使用这个方便的 NumberPicker 扩展对话框，它将您的 Double 值缩放到合适的 Int 范围并将 Int 值转换回 Doubles在调用任何回调之前。所以它基本上隐藏了NumberPicker只支持Int的事实。感觉NumberPicker居然会支持Double，试试看！

这是您需要复制和粘贴的片段扩展：

fun Fragment.showNumberPickerDialog(
    title: String,
    value: Double,
    range: ClosedRange<Double>,
    stepSize: Double,
    formatToString: (Double) -> String,
    valueChooseAction: (Double) -> Unit
) {
    val numberPicker = NumberPicker(context).apply {
        setFormatter { formatToString(it.toDouble() * stepSize) }
        wrapSelectorWheel = false

        minValue = (range.start / stepSize).toInt()
        maxValue = (range.endInclusive / stepSize).toInt()
        this.value = (value.toDouble() / stepSize).toInt()

        // NOTE: workaround for a bug that rendered the selected value wrong until user scrolled, see also: https://stackoverflow.com/q/27343772/3451975
        (NumberPicker::class.java.getDeclaredField("mInputText").apply { isAccessible = true }.get(this) as EditText).filters = emptyArray()
    }

    MaterialAlertDialogBuilder(context)
        .setTitle(title)
        .setView(numberPicker)
        .setPositiveButton("OK") { _, _ -> valueChooseAction(numberPicker.value.toDouble() * stepSize) }
        .setNeutralButton("Cancel") { _, _ -> /* do nothing, closes dialog automatically */ }
        .show()
}

现在您可以像这样使用它（在Fragment 中）：

showNumberPickerDialog(
    title = "Your Weight",
    value = 75.0, // in kilograms
    range = 10.0 .. 300.0,
    stepSize = 0.1,
    formatToString = { "$it kg" },
    valueChooseAction = { saveNewWeight(it) }
)