自学鸿蒙应用开发（7）- Picker组件
自学鸿蒙应用开发（7）- Picker组件
面向对象思考
发布于 2020-12-31 15:02:20
发布于 2020-12-31 15:02:20
本文介绍在鸿蒙应用中Picker组件的基本用法。
增加Picker组件
如下代码中46行~56行所示，在布局中增加Picker组件。
<?xml version="1.0" encoding="utf-8"?>
<DirectionalLayout
xmlns:ohos="http://schemas.huawei.com/res/ohos"
ohos:height="match_parent"
ohos:width="match_parent"
ohos:orientation="vertical">
<Component
ohos:height="0vp"
ohos:weight="3"
ohos:width="match_parent"
/>
<DirectionalLayout
xmlns:ohos="http://schemas.huawei.com/res/ohos"
ohos:height="match_content"
ohos:width="match_content"
ohos:layout_alignment="center"
ohos:orientation="vertical">
<Image
ohos:id="$+id:image"
ohos:width="match_content"
ohos:height="match_content"
ohos:layout_alignment="center"
ohos:image_src="$media:DevEco"
/>
<TextField
ohos:id="$+id:text_field"
ohos:width="match_parent"
ohos:height="30vp"
ohos:text_size="20fp"
ohos:text_alignment="center"
ohos:hint="Please input text and press [Click me!] button."
ohos:background_element="$graphic:background_text_field"
/>
<Button
ohos:id="$+id:hello_button"
ohos:width="match_content"
ohos:height="match_content"
ohos:text_size="27fp"
ohos:text="Click me!"
ohos:layout_alignment="center"
ohos:background_element="$graphic:background_button"
ohos:margin="15vp"
ohos:right_padding="8vp"
ohos:left_padding="8vp"
/>
<Picker
ohos:id="$+id:test_picker"
ohos:height="match_content"
ohos:width="300vp"
ohos:min_value="0"
ohos:max_value="6"
ohos:wheel_mode_enabled="true"
ohos:background_element="#E1FFFF"
ohos:layout_alignment="horizontal_center"
ohos:normal_text_size="16fp"
ohos:selected_text_size="32fp"/>
</DirectionalLayout>
<Component
ohos:height="0vp"
ohos:weight="5"
ohos:width="match_parent"
/>
</DirectionalLayout>代码中组件id被指定为test_picker，会在下面的响应代码中用到。
获取Picker组件设定和取得表示信息
如下面代码中30行和36行所示，在获取PIcker组件后，设定表示信息并在动作响应代码将最新表示信息设定到TextField组件上。
package com.example.helloharmony.slice;
import com.example.helloharmony.ResourceTable;
import ohos.aafwk.ability.AbilitySlice;
import ohos.aafwk.content.Intent;
import ohos.agp.components.Button;
import ohos.agp.components.Component;
import ohos.agp.components.Picker;
import ohos.agp.components.TextField;
import ohos.agp.utils.LayoutAlignment;
import ohos.agp.window.dialog.ToastDialog;
public class ComponentAbilitySlice extends AbilitySlice {
@Override
public void onStart(Intent intent) {
super.onStart(intent);
super.setUIContent(ResourceTable.Layout_ability_component);
//获取textfield输入组件
TextField tf = (TextField) findComponentById(ResourceTable.Id_text_field);
//获取button组件
Button button = (Button) findComponentById(ResourceTable.Id_hello_button);
// 为按钮设置点击事件回调
button.setClickedListener(new Component.ClickedListener() {
public void onClick(Component v) {
new ToastDialog(getContext())
.setText(tf.getText())
.show();
}
});
//获取picker组件
Picker picker = (Picker) findComponentById(ResourceTable.Id_test_picker);
//设定表示文字
picker.setDisplayedData(new String[]{"Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun"});
//设定事件响应
picker.setValueChangedListener((picker1, oldVal, newVal) -> {
tf.setText(picker1.getDisplayedData()[newVal - picker1.getMinValue()]);
});
}
@Override
public void onActive() {
super.onActive();
}
@Override
public void onForeground(Intent intent) {
super.onForeground(intent);
}
}画面显示如下：参考文档
Picker类：
https://developer.harmonyos.com/cn/docs/documentation/doc-references/picker-0000001054119976
Picker组件：
https://developer.harmonyos.com/cn/docs/documentation/doc-guides/ui-java-component-picker-0000001059807909
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原始发表：2020-12-29，如有侵权请联系?cloudcommunity@tencent.com 删除
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