Ionic rest can't post in rest server

Ionic Framework
1

i have a problem, when i post data in databse can’t enter, this file, provider/rest.ts
import { HttpClient } from ‘@angular/common/http’;
import { Injectable } from ‘@angular/core’;
import {Http, Headers} from ‘@angular/http’;
import ‘rxjs/add/operator/map’;
@Injectable()
export class RestProvider {

// var headers = new Headers();
// headers.append(headerName, value);

apiUrl = ‘http://localhost:8080’;
data ={“namaTempat”:"", “latitude”:"",“longlitude”:""};

constructor(public http: HttpClient) {
console.log(‘Hello RestProvider Provider’);
}

saveUser(data) {
return new Promise((resolve, reject) => {
this.http.post(this.apiUrl+’/item’, JSON.stringify(data))
.subscribe(res => {
resolve(res);
}, (err) => {
reject(err);
});
});
}

in home.ts
@Component({
selector: ‘page-home’,
templateUrl: ‘home.html’
})
export class HomePage {

userData: {“namaTempat”:"", “latitude”:"",“longlitude”:""};

saveUser() {
  console.log(this.namaTempat,this.latitude, this.longitude);
  this.restProvider.saveUser(this.namaTempat, this.latitude, this.longitude).then((result) => {
    result = this.namaTempat, this.latitude, this.longlitude;
    localStorage.setItem('/item', JSON.stringify(this.responseData));
    console.log('Succes Saved');

  }, (err) => {
    console.log(err)
  });

}

and in home.html

name latitude {{ latitude }} longlitude {{ longitude }} Save please help me , thnks.