Android NumberPicker：从 XML 设置最小值、最大值、默认值
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Android NumberPicker: Set min, max, default from XML
提问by Adam Matan
Is there a way to set the minimum, maximum and default values of a NumberPickerfrom the XML Layout?
有没有办法从 XML 布局设置NumberPicker的最小值、最大值和默认值？
I'm doing it from within the Activity code:
我在活动代码中这样做：
np = (NumberPicker) findViewById(R.id.np);
np.setMaxValue(120);
np.setMinValue(0);
np.setValue(30);
XML is obviously more appropriate , because it defines property, not behaviour.
XML 显然更合适，因为它定义了属性，而不是行为。
Is there a way to set these using the XML layout?
有没有办法使用 XML 布局来设置这些？
回答by MazeChaZer
I had the same problem, this is how I solved it (according to the comment of MKJParekh):
我遇到了同样的问题，这就是我解决它的方法（根据 MKJParekh 的评论）：
I created my own NumberPicker-Class
package com.exaple.project; import android.annotation.TargetApi; import android.content.Context; import android.os.Build; import android.util.AttributeSet; import android.widget.NumberPicker; @TargetApi(Build.VERSION_CODES.HONEYCOMB)//For backward-compability public class MyNumberPicker extends NumberPicker { public MyNumberPicker(Context context) { super(context); } public MyNumberPicker(Context context, AttributeSet attrs) { super(context, attrs); processAttributeSet(attrs); } public MyNumberPicker(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); processAttributeSet(attrs); } private void processAttributeSet(AttributeSet attrs) { //This method reads the parameters given in the xml file and sets the properties according to it this.setMinValue(attrs.getAttributeIntValue(null, "min", 0)); this.setMaxValue(attrs.getAttributeIntValue(null, "max", 0)); } }Now you can use this NumberPicker in your xml layout file
<com.exaple.project.myNumberPicker android:id="@+id/numberPicker1" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_gravity="center" android:orientation="vertical" max="100" min="1" />
我创建了自己的 NumberPicker-Class
package com.exaple.project; import android.annotation.TargetApi; import android.content.Context; import android.os.Build; import android.util.AttributeSet; import android.widget.NumberPicker; @TargetApi(Build.VERSION_CODES.HONEYCOMB)//For backward-compability public class MyNumberPicker extends NumberPicker { public MyNumberPicker(Context context) { super(context); } public MyNumberPicker(Context context, AttributeSet attrs) { super(context, attrs); processAttributeSet(attrs); } public MyNumberPicker(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); processAttributeSet(attrs); } private void processAttributeSet(AttributeSet attrs) { //This method reads the parameters given in the xml file and sets the properties according to it this.setMinValue(attrs.getAttributeIntValue(null, "min", 0)); this.setMaxValue(attrs.getAttributeIntValue(null, "max", 0)); } }现在你可以在你的 xml 布局文件中使用这个 NumberPicker
<com.exaple.project.myNumberPicker android:id="@+id/numberPicker1" android:layout_width="match_parent" android:layout_height="wrap_content" android:layout_gravity="center" android:orientation="vertical" max="100" min="1" />
Thanks to MKJParekh for his useful comment
感谢 MKJParekh 的有用评论
回答by AjahnCharles
Here is an updated version that follows the Android Docs
(and thus supports theming & Android Studio designer preview)
这是遵循Android Docs的更新版本
（因此支持主题和 Android Studio 设计器预览）
values/attrs.xml:
值/attrs.xml：
<?xml version="1.0" encoding="utf-8"?>
<resources>
<declare-styleable name="NumberPickerWithXml">
<attr name="maxValue" format="integer" />
<attr name="minValue" format="integer" />
<attr name="defaultValue" format="integer" />
</declare-styleable>
</resources>
NumberPickerWithXml.kt:
NumberPickerWithXml.kt:
package com.example.library.ui
import android.content.Context
import android.util.AttributeSet
import android.widget.NumberPicker
import com.example.library.ui.R
class NumberPickerWithXml : NumberPicker {
constructor(context: Context) : super(context)
constructor(context: Context, attrs: AttributeSet) : super(context, attrs) {
processXmlAttributes(attrs)
}
constructor(context: Context, attrs: AttributeSet, defStyleAttr: Int) : super(context, attrs, defStyleAttr) {
processXmlAttributes(attrs, defStyleAttr)
}
constructor(context: Context, attrs: AttributeSet, defStyleAttr: Int, defStyleRes: Int) : super(context, attrs, defStyleAttr, defStyleRes) {
processXmlAttributes(attrs, defStyleAttr, defStyleRes)
}
private fun processXmlAttributes(attrs: AttributeSet, defStyleAttr: Int = 0, defStyleRes: Int = 0) {
val attributes = context.theme.obtainStyledAttributes(attrs, R.styleable.NumberPickerWithXml, defStyleAttr, defStyleRes)
try {
this.minValue = attributes.getInt(R.styleable.NumberPickerWithXml_minValue, 0)
this.maxValue = attributes.getInt(R.styleable.NumberPickerWithXml_maxValue, 0)
this.value = attributes.getInt(R.styleable.NumberPickerWithXml_defaultValue, 0)
} finally {
attributes.recycle()
}
}
}
...or NumberPickerWithXml.java (untested):
...或 NumberPickerWithXml.java（未经测试）：
package com.example.library.ui
import android.content.Context
import android.util.AttributeSet
import android.widget.NumberPicker
import com.example.library.ui.R
public class NumberPickerWithXml extends NumberPicker {
public NumberPickerWithXml(Context context) {
super(context);
}
public NumberPickerWithXml(Context context, AttributeSet: attrs) {
super(context, attrs);
processXmlAttributes(attrs, 0, 0);
}
public NumberPickerWithXml(Context context, AttributeSet: attrs, int: defStyleAttr) {
super(context, attrs, defStyleAttr);
processXmlAttributes(attrs, defStyleAttr, 0);
}
public NumberPickerWithXml(Context context, AttributeSet: attrs, int: defStyleAttr, int: defStyleRes) {
super(context, attrs, defStyleAttr, defStyleRes);
processXmlAttributes(attrs, defStyleAttr, defStyleRes);
}
private void processXmlAttributes(AttributeSet: attrs, int: defStyleAttr, int: defStyleRes) {
TypedArray attributes = context.getTheme().obtainStyledAttributes(attrs, R.styleable.NumberPickerWithXml, defStyleAttr, defStyleRes)
try {
this.minValue = attributes.getInt(R.styleable.NumberPickerWithXml_minValue, 0);
this.maxValue = attributes.getInt(R.styleable.NumberPickerWithXml_maxValue, 0);
this.value = attributes.getInt(R.styleable.NumberPickerWithXml_defaultValue, 0);
} finally {
attributes.recycle();
}
}
}
Usage in your layout:
在您的布局中的用法：
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:custom="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools">
<com.example.library.ui.NumberPickerWithXml
android:layout_width="wrap_content"
android:layout_height="wrap_content"
custom:defaultValue="30"
custom:maxValue="120"
custom:minValue="0" />
</LinearLayout>
