HarmonyOS 鸿蒙Next DataChangeListener.onDatasetChange问题
HarmonyOS 鸿蒙Next DataChangeListener.onDatasetChange问题 点击"从头部填加一个"按钮那里有注释,跟期望不太一样
export class LazyForEachAdapter<T> implements IDataSource {
private listeners: DataChangeListener[] = [];
originDataArray: T[] = [];
public totalCount(): number {
return this.originDataArray.length;
}
public getData(index: number): T {
return this.originDataArray[index];
}
registerDataChangeListener(listener: DataChangeListener): void {
if (this.listeners.indexOf(listener) < 0) {
this.listeners.push(listener);
}
}
unregisterDataChangeListener(listener: DataChangeListener): void {
const pos = this.listeners.indexOf(listener);
if (pos >= 0) {
// console.info('remove listener');
this.listeners.splice(pos, 1);
}
}
notifyDataReload(): void {
this.listeners.forEach(listener => {
listener.onDataReloaded()
})
}
notifyDataAdd(index: number): void {
this.listeners.forEach(listener => {
listener.onDataAdd(index);
})
}
notifyDataChange(index: number): void {
this.listeners.forEach(listener => {
listener.onDataChange(index);
})
}
notifyDataDelete(index: number): void {
this.listeners.forEach(listener => {
listener.onDataDelete(index);
})
}
notifyDataMove(from: number, to: number): void {
this.listeners.forEach(listener => {
listener.onDataMove(from, to);
})
}
//DataAddOperation | DataDeleteOperation | DataChangeOperation | DataMoveOperation | DataExchangeOperation | DataReloadOperation
/**
* 使用这个api的时候,这个类只能使用onDatasetChange这一种形式,也就是类中只能包含onDatasetChange刷新方式要么就不包含要不就报错
* @param dataOperations
*/
notifyWithDataOperation(dataOperations: DataOperation[]): void {
this.listeners.forEach(listener => {
listener.onDatasetChange(dataOperations)
})
}
notifyDataReloadWithOperation(): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{} as DataReloadOperation])
})
}
notifyDataRemoveWithOperation(index: number, count?: number): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{
index: index,
//默认是一个
count: count
} as DataDeleteOperation])
})
}
notifyDataAddWithOperation(index: number, count?: number, key?: string | string[] | undefined): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{
index: index,
//默认是一个
count: count,
//Key of added data
key: key
} as DataAddOperation])
})
}
notifyDataChangeWithOperation(index: number, key?: string): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{
index: index,
key: key
} as DataChangeOperation])
})
}
notifyDataMoveWithOperation(from: number, to: number, key?: string): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{
index: {
from: from,
to: to
},
key: key
} as DataMoveOperation])
})
}
notifyDataExChangeWithOperation(index: ExchangeIndex, key?: ExchangeKey): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{
index: index,
key: key
} as DataExchangeOperation])
})
}
}
@Entry
@Component
struct swiperIndicatorPage {
private adapter: LazyForEachAdapter<string> = new LazyForEachAdapter()
aboutToAppear(): void {
this.adapter.originDataArray.push(...["测试1", "测试2"])
}
build() {
Column() {
Text("从头部填加一个")
.width("100%")
.height(44)
.onClick(() => {
this.adapter.originDataArray.unshift("头部添加的")
//方式1是有效的
//this.adapter.notifyDataAdd(0)
//方式2是直接添加在底部并且是:"测试2",跟预期的不一样
this.adapter.notifyDataAddWithOperation(0, 1,("头部添加的" + 0))
})
List() {
LazyForEach(this.adapter, (value: string, index) => {
ListItem(){
Text(value)
.width("100%")
.height(44)
}
}, (value: string, index: number) => {
return value + index
})
}
}
}
更多关于HarmonyOS 鸿蒙Next DataChangeListener.onDatasetChange问题的实战系列教程也可以访问 https://www.itying.com/category-93-b0.html
这边需要加上type: DataOperationType.ADD,具体使用可以参考:
https://developer.huawei.com/consumer/cn/doc/harmonyos-guides-V5/arkts-rendering-control-lazyforeach-V5#非首次渲染
export class LazyForEachAdapter implements IDataSource {
private listeners: DataChangeListener[] = [];
originDataArray: T[] = [];
public totalCount(): number {
return this.originDataArray.length;
}
public getData(index: number): T {
return this.originDataArray[index];
}
registerDataChangeListener(listener: DataChangeListener): void {
if (this.listeners.indexOf(listener) < 0) {
this.listeners.push(listener);
}
}
unregisterDataChangeListener(listener: DataChangeListener): void {
const pos = this.listeners.indexOf(listener);
if (pos >= 0) {
this.listeners.splice(pos, 1);
}
}
notifyDataReload(): void {
this.listeners.forEach(listener => {
listener.onDataReloaded();
})
}
notifyDataAdd(index: number): void {
this.listeners.forEach(listener => {
listener.onDataAdd(index);
})
}
notifyDataChange(index: number): void {
this.listeners.forEach(listener => {
listener.onDataChange(index);
})
}
notifyDataDelete(index: number): void {
this.listeners.forEach(listener => {
listener.onDataDelete(index);
})
}
notifyDataMove(from: number, to: number): void {
this.listeners.forEach(listener => {
listener.onDataMove(from, to);
})
}
//DataAddOperation | DataDeleteOperation | DataChangeOperation | DataMoveOperation | DataExchangeOperation | DataReloadOperation
/**
使用这个api的时候,这个类只能使用onDatasetChange这一种形式,也就是类中只能包含onDatasetChange刷新方式要么就不包含要不就报错
@param dataOperations
*/
notifyWithDataOperation(dataOperations: DataOperation[]): void {
this.listeners.forEach(listener => {
listener.onDatasetChange(dataOperations)
})
}
notifyDataReloadWithOperation(): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{} as DataReloadOperation])
})
}
notifyDataRemoveWithOperation(index: number, count?: number): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{
index: index,
//默认是一个
count: count
} as DataDeleteOperation])
})
}
notifyDataAddWithOperation(index: number, count?: number, key?: string | string[] | undefined): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{
type: DataOperationType.ADD,
index: index,
} as DataAddOperation])
})
}
notifyDataChangeWithOperation(index: number, key?: string): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{
index: index,
key: key
} as DataChangeOperation])
})
}
notifyDataMoveWithOperation(from: number, to: number, key?: string): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{
index: {
from: from,
to: to
},
key: key
} as DataMoveOperation])
})
}
notifyDataExChangeWithOperation(index: ExchangeIndex, key?: ExchangeKey): void {
this.listeners.forEach(listener => {
listener.onDatasetChange([{
index: index,
key: key
} as DataExchangeOperation])
})
}
}
@Entry
@Component
struct swiperIndicatorPage {
private adapter: LazyForEachAdapter = new LazyForEachAdapter()
aboutToAppear(): void {
this.adapter.originDataArray.push(...["测试1", "测试2"])
}
build() {
Column() {
Text("从头部填加一个")
.width("100%")
.height(44)
.onClick(() => {
this.adapter.originDataArray.unshift("头部添加的")
//方式1是有效的
//this.adapter.notifyDataAdd(0)
//方式2是直接添加在底部并且是:"测试2",跟预期的不一样
// this.adapter.originDataArray.splice(0, 0, "头部添加的" + 0);
this.adapter.notifyDataAddWithOperation(0)
})
List() {
LazyForEach(this.adapter, (value: string, index) => {
ListItem() {
Text(value)
.width("100%")
.height(44)
}
}, (value: string, index: number) => {
return value + index
})
}
}
}
}
更多关于HarmonyOS 鸿蒙Next DataChangeListener.onDatasetChange问题的实战系列教程也可以访问 https://www.itying.com/category-93-b0.html
针对帖子标题中提到的HarmonyOS(鸿蒙)Next DataChangeListener.onDatasetChange问题,以下是根据要求提供的简洁回答:
在HarmonyOS中,DataChangeListener
接口用于监听数据集的变化。onDatasetChange
方法是该接口的核心方法,当数据集发生变化时会被触发。如果你遇到了onDatasetChange
方法不工作或者表现异常的问题,可能的原因包括但不限于:
-
监听器未正确注册:确保你的
DataChangeListener
实例已经被正确注册到相应的数据源或组件上。 -
数据源未更新:检查触发
onDatasetChange
的数据源是否确实发生了更新。有时候数据源更新逻辑可能有误,导致监听器无法被触发。 -
线程问题:如果数据更新和监听器回调在不同的线程上执行,可能会遇到线程同步问题。确保数据更新和监听器回调在正确的线程上执行。
-
权限问题:某些数据集可能需要特定的权限才能访问或监听其变化,确保你的应用已经获得了这些权限。
-
版本兼容性:检查你的HarmonyOS SDK版本是否与你的开发环境兼容,有时候版本更新会带来API的变更。
如果以上检查都无法解决问题,可能是更深层次的系统或框架问题。此时,建议直接联系官网客服以获取更专业的帮助。官网地址是: