HarmonyOS ArkTS怎么写回调事件监听

参考示例如下：

export interface test {
  getTest: (info: TestInterface) => void
}

export class TestInterface {
  public test: test | null = null
  public infos: string = ""

  public setTestListener(test: test) {
    this.test = test
  }

  public getATest(info: TestInterface) {
    this.test?.getTest(info)
  }
}

export class TestClass {
  public t1: TestInterface | null = null
  constructor() {
    this.t1 = new TestInterface()

    let test: test = {
      getTest: (info: TestInterface) => {
        console.log("this interface has been constructed, and this method has done, the info is : " + info.infos)
      }
    }
    this.t1.setTestListener(test)
  }

  doATest(info: string) {
    this.t1!.infos = info
    this.t1?.getATest(this.t1)
  }
}

@Entry(localStorage)
@Component
struct Index {
  tc: TestClass = new TestClass()

  build() {
    Column() {
      Text("test")
      Button("click").onClick(() => {
        this.tc.doATest("叮咚FM")
      })
    }
  }
}
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