HarmonyOS 鸿蒙Next ForEach中item的数字如何做累加，代码如下
HarmonyOS 鸿蒙Next ForEach中item的数字如何做累加，代码如下
请教各位，代码如下，有什么办法可以把三个计数器中的数字累加起来～
@Entry
@Component
struct Index {
private num: number = 0
build() {
Column({ space: 20 }) {
ForEach(DATA, (item: Goods) => {
Comp({ str: item.goodsCount })
})
Text(`总数: ${this.num}`).fontSize(25)
}.width('100%')
}
}
@Component
struct Comp {
private str: number = 0
@State num: number = 0
build() {
Row({ space: 20 }) {
Text(this.str.toString())
Row() {
Button('-').type(ButtonType.Normal).onClick(() => {
this.num--
})
Text(this.num.toString())
Button('+').type(ButtonType.Normal).onClick(() => {
this.num++
})
}
}
}
}
export class Goods {
goodsCount: number = 0 // 总数量
constructor(goodsCount: number) {
this.goodsCount = goodsCount
}
}
const DATA: Goods[] = [
new Goods(1),
new Goods(2),
new Goods(3)
]更多关于HarmonyOS 鸿蒙Next ForEach中item的数字如何做累加，代码如下的实战系列教程也可以访问 https://www.itying.com/category-93-b0.html
7 回复
@Entry
@Component
struct Index {
@State num: number = 0
aboutToAppear(): void {
let tempTotal = 0
for (let i = 0; i < DATA.length; i++) {
tempTotal += DATA[i].goodsCount
}
this.num = tempTotal
}
build() {
Column({ space: 20 }) {
ForEach(DATA, (item: Goods, index: number) {
Comp({
str: item.goodsCount,
item: item,
onChange: (value: string) => {
DATA[index] = JSON.parse(value) as Goods
this.aboutToAppear()
}
})
})
Text(`总数: ${this.num}`).fontSize(25)
}.width('100%')
}
}
@Component
struct Comp {
@Prop item: Goods
private str: number = 0
onChange: Function = () => {
}
build() {
Row({ space: 20 }) {
Text(this.str.toString())
Row() {
Button('-').type(ButtonType.Normal).onClick(() => {
this.item.goodsCount--
this.onChange(JSON.stringify(this.item))
})
Text(this.item.goodsCount.toString())
Button('+').type(ButtonType.Normal).onClick(() => {
this.item.goodsCount++
this.onChange(JSON.stringify(this.item))
})
}
}
}
}
export class Goods {
goodsCount: number = 0 // 总数量
constructor(goodsCount: number) {
this.goodsCount = goodsCount
}
}
const DATA: Goods[] = [
new Goods(1),
new Goods(2),
new Goods(3)
]更多关于HarmonyOS 鸿蒙Next ForEach中item的数字如何做累加，代码如下的实战系列教程也可以访问 https://www.itying.com/category-93-b0.html
找HarmonyOS工作还需要会Flutter的哦，有需要Flutter教程的可以学学大地老师的教程，很不错，B站免费学的哦：BV1S4411E7LY/?p=17
方案三，在类中添加一个变量纪录总数
@Entry
@Component
struct Index {
@State num: number = 0
private goods: Array<Goods> = DATA;
onCountChange() {
let localTotalMoney = 0;
this.goods.forEach((item, index) => {
localTotalMoney += item.goodsCount
})
this.num = localTotalMoney
}
build() {
Column({ space: 20 }) {
ForEach(this.goods, (item: Goods) => {
Comp({ str: item.Count, onCountChange: (newCount: number) => {
item.goodsCount = newCount
this.onCountChange()
} })
})
Text(`总数: ${this.num}`).fontSize(25)
}.width('100%')
}
}
@Component
struct Comp {
private str: number = 0
@State num: number = 0
private onCountChange: (newCount: number) => void;
build() {
Row({ space: 20 }) {
Text(this.str.toString())
Row() {
Button('-').type(ButtonType.Normal).onClick(() => {
this.num--
this.onCountChange(this.num)
})
Text(this.num.toString())
Button('+').type(ButtonType.Normal).onClick(() => {
this.num++
this.onCountChange(this.num)
})
}
}
}
}
export class Goods {
Count: number; //数量
goodsCount: number = 0 //总数量
constructor(Count: number) {
this.Count = Count
}
}
const DATA: Goods[] = [
new Goods(1),
new Goods(2),
new Goods(3)
]方案二
@Entry
@Component
struct Index {
@State DATA: Goods[] = [
new Goods(),
new Goods(),
new Goods()
]
@State num: number = 0
onGoodsCountChange(index: number, delta: number): void {
this.DATA[index].goodsCount += delta
this.DATA[index] = JSON.parse(JSON.stringify(this.DATA[index]))
let tempTotal = 0
for (let i = 0; i < this.DATA.length; i++) {
tempTotal += this.DATA[i].goodsCount
}
this.num = tempTotal
}
build() {
Column({ space: 20 }) {
ForEach(this.DATA, (item: Goods, index: number) => {
Comp({
index: index,
item: item,
onChange: (delta: number) => this.onGoodsCountChange(index, delta)
})
})
Text(`总数: ${this.num}`).fontSize(25)
}.width('100%')
}
}
@Component
struct Comp {
@Prop item: Goods
private index: number = 0
onChange: Function = () => {
}
build() {
Row({ space: 20 }) {
Text((this.index + 1).toString())
Row() {
Button('-').type(ButtonType.Normal).onClick(() => {
this.onChange(-1)
})
Text(this.item.goodsCount.toString())
Button('+').type(ButtonType.Normal).onClick(() => {
this.onChange(1)
})
}
}
}
}
export class Goods {
goodsCount: number = 0 // 总数量
}
在HarmonyOS中，ForEach用于遍历数组并生成UI组件。要在ForEach中对item的数字进行累加，可以通过在ForEach外部定义一个变量来存储累加结果，并在遍历过程中更新该变量。以下是一个示例代码：
@Entry
@Component
struct MyComponent {
@State numbers: number[] = [1, 2, 3, 4, 5];
@State sum: number = 0;
build() {
Column() {
ForEach(this.numbers, (item: number) => {
this.sum += item;
Text(`Item: ${item}, Sum: ${this.sum}`)
})
}
}
}在这个示例中，sum变量用于存储累加结果。每次遍历时，sum会加上当前的item值，并显示在Text组件中。注意，sum需要在@State中声明，以便在UI更新时保持状态。
在HarmonyOS的ForEach中，你可以通过定义一个累加变量来实现数字的累加。以下是一个示例代码：
@State numbers: number[] = [1, 2, 3, 4, 5];
@State sum: number = 0;
build() {
Column() {
ForEach(this.numbers, (item: number) => {
this.sum += item;
Text(`Item: ${item}, Sum: ${this.sum}`)
})
}
}在这个例子中，sum变量会在每次遍历时累加item的值，并显示当前累加结果。
