小编Lui*_*ino的帖子

按照指南:https: //www.primefaces.org/primeng/我已经尝试安装PrimeNG与Angular4一起使用,按照上面详述的步骤,但是我收到错误:

'p-dropdown' is not a known element:

我尝试重建项目,正如其他帖子所建议的那样,但它对我不起作用.任何提示？

以下是所有细节:

- PrimeNg安装

npm install primeng --save

- file:testdropdown.component.html

<p-dropdown [options]="cities" [(ngModel)]="selectedCity"></p-dropdown>

- file:testdropdown.component.ts

import { DropdownModule } from 'primeng/primeng';
import { Component, OnInit } from '@angular/core';
import { SelectItem } from 'primeng/primeng';

@Component({
  selector: 'app-testdropdown',
  templateUrl: './testdropdown.component.html',
  styleUrls: ['./testdropdown.component.css']
})
export class TestdropdownComponent implements OnInit {

  cities: SelectItem[];

  selectedCity: string;

  constructor() {

  this.cities = [];
    this.cities.push({ label: 'Select City', value: null });
    this.cities.push({ label: 'New York', value: { …

在以下示例中

• test instanceof java.util.Map返回false

• 测试instanceof java.util.HashMap无法编译

但

• mymap instanceof Set返回false和
• mymap instanceof HashSet返回false(为什么要编译？!？)

为什么？他们看起来彼此如此相似!

import java.util.Map;
import java.util.HashMap;
import java.util.Set;
import java.util.HashSet;

public class InstanceofTest {
    public static class Test {}
    public static void main(String[] args) {
        // -- left operand references a Class instance
        Test test = null;

        // 1. outputs: false
        System.out.println(test instanceof Map);

        // 2. COMPILATION ERROR
        System.out.println(test instanceof HashMap);


        // -- left operand references an Interface instance
        Map mymap = new HashMap();

        // 3. outputs: false …