angular 提示MainComponent is not d

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

@Component({
  selector: 'app-main-page',
  templateUrl: './main.component.html',
  styleUrls: ['./main.component.css']
})
export class MainComponent {
}

export class MainComponent {
}
这里提示红色，提示没有任何一个moudle里面定义使用。解决在app.moudle.ts定义即可

import {NgModule} from '@angular/core';
import {BrowserModule} from '@angular/platform-browser';
import {RouterModule} from '@angular/router';
import {NzButtonModule} from 'ng-zorro-antd/button';
import {AppComponent} from './app.component';
import {LoginComponent} from './login/login.component';
import {NZ_I18N} from 'ng-zorro-antd/i18n';
import {zh_CN} from 'ng-zorro-antd/i18n';
import {registerLocaleData} from '@angular/common';
import zh from '@angular/common/locales/zh';
import {FormsModule} from '@angular/forms';
import {HttpClientModule} from '@angular/common/http';
import {BrowserAnimationsModule} from '@angular/platform-browser/animations';
import {MainComponent} from './main/main.component';

registerLocaleData(zh);

@NgModule({
  declarations: [
    AppComponent,
    LoginComponent,
    MainComponent
  ],
  imports: [
    BrowserModule,
    FormsModule,
    HttpClientModule,
    BrowserAnimationsModule,
    NzButtonModule,
    RouterModule.forRoot([
      {path: 'login-component', component: LoginComponent},
      {path: 'app', component: AppComponent}
    ])
  ],
  providers: [{provide: NZ_I18N, useValue: zh_CN}],
  bootstrap: [AppComponent]
})
export class AppModule {
}

主要是下面两句

import {MainComponent} from './main/main.component';
declarations: [
    AppComponent,
    LoginComponent,
    MainComponent
  ],