自学鸿蒙应用开发(12)- Checkbox
本文介绍在鸿蒙应用中Checkbox组件的基本用法。
增加Checkbox组件
如下代码中47行~52行所示,在布局中增加Checkbox组件。
<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"
/>
<Checkbox
ohos:id="$+id:check_box"
ohos:height="match_content"
ohos:width="match_content"
ohos:layout_alignment="center"
ohos:text="24小时制"
ohos:text_size="20fp" />
<TimePicker
ohos:id="$+id:time_picker"
ohos:24_hour_mode="false"
ohos:height="match_content"
ohos:width="match_parent"
ohos:layout_alignment="horizontal_center"
ohos:text_am="AM"
ohos:text_pm="PM"
ohos:normal_text_size="20fp"
ohos:selected_text_size="25fp"/>
DirectionalLayout>
<Component
ohos:height="0vp"
ohos:weight="5"
ohos:width="match_parent"
/>
DirectionalLayout>
代码中组件id被指定为check_box,会在下面的响应代码中用到。
在代码中使用Checkbox组件
下面代码中的第20行获取RadioContainer组件后,在第24行根据Checkbox的状态更新TimePicker的形式,然后在第42行~45行为Checkbox增加响应处理,其内容是同样是根据Checkbox的状态更新TimePicker的形式。
package com.example.helloharmony.slice;
import com.example.helloharmony.ResourceTable;
import ohos.aafwk.ability.AbilitySlice;
import ohos.aafwk.content.Intent;
import ohos.agp.components.*;
import ohos.agp.window.dialog.ToastDialog;
import java.time.LocalTime;
import java.time.temporal.ChronoUnit;
public class ComponentAbilitySlice extends AbilitySlice {
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);
//获取Checkbox组件
Checkbox check_box = (Checkbox)findComponentById(ResourceTable.Id_check_box);
//获取TimePicker组件
TimePicker picker = (TimePicker) findComponentById(ResourceTable.Id_time_picker);
//根据Checkbox的状态设定TimePicker的形式。
picker.set24Hour(check_box.isChecked());
// 为按钮设置点击事件回调
button.setClickedListener(new Component.ClickedListener() {
public void onClick(Component v) {
LocalTime rightNow = LocalTime.now();
LocalTime pickTime = LocalTime.of(picker.getHour(), picker.getMinute(), picker.getSecond());
String msg;
if(pickTime.isBefore(rightNow))
msg = "所选时间比现在时刻早" + pickTime.until(rightNow, ChronoUnit.SECONDS) + "秒";
else if(pickTime.isAfter(rightNow))
msg = "所选时间比现在时刻晚" + rightNow.until(pickTime, ChronoUnit.SECONDS) + "秒";
else
msg = "所选时间和现在时刻一样";
new ToastDialog(getContext())
.setText(msg)
.show();
}
});
//为RadioContainer设置事件响应
check_box.setCheckedStateChangedListener((view, state) -> {
picker.set24Hour(state);
});
//为TimePicker设定事件响应
picker.setTimeChangedListener(
new TimePicker.TimeChangedListener() {
public void onTimeChanged(TimePicker timePicker, int hour, int minute, int second) {
tf.setText(hour + ":" + minute + ":" + second);
}
}
);
}
public void onActive() {
super.onActive();
}
public void onForeground(Intent intent) {
super.onForeground(intent);
}
}
画面显示如下:
参考文档
Checkbox组件
https://developer.harmonyos.com/cn/docs/documentation/doc-guides/ui-java-component-checkbox-0000001060487804
Checkbox类
https://developer.harmonyos.com/cn/docs/documentation/doc-references/checkbox-0000001054558715
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