Angular:9如何从另一个同级组件中更改变量？

ng generate service shared

import { Injectable } from '@angular/core';

@Injectable({
  providedIn: 'root'
})
export class SharedService {
  private sharedVariable: string;

  constructor() { }

  setSharedVariable(value: string) {
    this.sharedVariable = value;
  }

  getSharedVariable() {
    return this.sharedVariable;
  }
}

import { Component } from '@angular/core';
import { SharedService } from '../shared/shared.service';

@Component({
  selector: 'app-component-a',
  template: `
    <button (click)="changeVariable()">Change Variable</button>
  `
})
export class ComponentA {
  constructor(private sharedService: SharedService) { }

  changeVariable() {
    this.sharedService.setSharedVariable('New Value');
  }
}

import { Component } from '@angular/core';
import { SharedService } from '../shared/shared.service';

@Component({
  selector: 'app-component-b',
  template: `
    <p>{{ sharedVariable }}</p>
  `
})
export class ComponentB {
  sharedVariable: string;

  constructor(private sharedService: SharedService) {
    this.sharedVariable = this.sharedService.getSharedVariable();
  }
}