Nativescript-angular: Can not open dialog by program

Created on 10 Apr 2018 · 2Comments · Source: NativeScript/nativescript-angular

I can not open an alert/confirm dialog by program, such as invoking confirm() in ngOnInit() function.
ERROR Error: Uncaught (in promise): Error: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources$Theme android.content.Context.getTheme()' on a null object reference JS: android.app.AlertDialog.resolveDialogTheme(AlertDialog.java:224) JS: android.app.AlertDialog$Builder.<init>(AlertDialog.java:454) JS: com.tns.Runtime.callJSMethodNative(Native Method) JS: com.tns.Runtime.dispatchCallJSMethodNative(Runtime.java:1088) JS: com.tns.Runtime.callJSMethodImpl(Runtime.java:970) JS: com.tns.Runtime.callJSMethod(Runtime.java:957) JS: com.tns.Runtime.callJSMethod(Runtime.java:941) JS: com.tns.Runtime.callJSMethod(Runtime.java:933) JS: com.tns.NativeScriptActivity.onStart(NativeScriptActivity.java:44) JS: android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1334) JS: android.app.Activity.performStart(Activity.java:7029) JS: android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2741) JS: android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) JS: android.app.ActivityThread.-wrap11(Unknown Source:0) JS: android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) JS: android.os.Handler.dispatchMessage(Handler.java:106) JS: android.os.Looper.loop(Looper.java:164) JS: android.app.ActivityThread.main(ActivityThread.java:6494) JS: java.lang.reflect.Method.invoke(Native Method) JS: com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) JS: com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) JS: Error: java.lang.NullPointerException: Attempt to invoke virtual method 'android.content.res.Resources$Theme android.content.Context.getTheme()' on a null object reference JS: android.app.AlertDialog.resolveDialogTheme(AlertDialog.java:224) JS: android.app.AlertDialog$Builder.<init>(AlertDialog.java:454) JS: com.tns.Runtime.callJSMethodNative(Native Method) JS: com.tns.Runtime.dispatchCallJSMethodNative(Runtime.java:1088) JS: com.tns.Runtime.callJSMethodImpl(Runtime.java:970) JS: com.tns.Runtime.callJSMethod(Runtime.java:957) JS: com.tns.Runtime.callJSMethod(Runtime.java:941) JS: com.tns.Runtime.callJSMethod(Runtime.java:933) JS: com.tns.NativeScriptActivity.onStart(NativeScriptActivity.java:44) JS: android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1334) JS: android.app.Activity.performStart(Activity.java:7029) JS: android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2741) JS: android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2856) JS: android.app.ActivityThread.-wrap11(Unknown Source:0) JS: android.app.ActivityThread$H.handleMessage(ActivityThread.java:1589) JS: android.os.Handler.dispatchMessage(Handler.java:106) JS: android.os.Looper.loop(Looper.java:164) JS: android.app.ActivityThread.main(ActivityThread.java:6494) JS: java.lang.reflect.Method.invoke(Native Method) JS: com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438) JS: com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807) JS: at createAlertDialog (file:///data/data/org.nativescript.MarketingAssistant/files/app/tns_modules/tns-core-modules/ui/dialogs/dialogs.js:12:17) JS: at file:///data/data/org.nativescript.MarketingAssistant/files/app/tns_modules/tns-core-modules/ui/dialogs/dialogs.js:121:27 JS: at new ZoneAwarePromise (file:///data/data/org.nativescript.MarketingAssistant/files/app/tns_modules/nativescript-angular/zone-js/dist/zone-nativescript.js:777:29) JS: at Object.confirm (file:///data/data/org.nativescript.MarketingAssistant/files/app/tns_modules/tns-core-modules/ui/dialogs/dialogs.js:118:12) ...
But the same code woks well when being invoked by onTap() like function.

env:
nativescript 3.4.3
tns-core-modules 3.4.1

Source

wanpeng2008

👍1

Most helpful comment

Hi @wanpeng2008,
In your scenario, you should way the UI to be loaded, before showing the alert. In this case, you can use ngAfterViewInit and set up timeout of 100 milliseconds, For example:

import { Component, OnInit } from "@angular/core";

import { Item } from "./item";
import { ItemService } from "./item.service";
import {Page} from "ui/page"
@Component({
    selector: "ns-items",
    moduleId: module.id,
    templateUrl: "./items.component.html",
})
export class ItemsComponent implements OnInit {
    items: Item[];

    constructor(private itemService: ItemService, private page:Page) {

     }

    ngOnInit(): void {
        this.items = this.itemService.getItems();
    }
    ngAfterViewInit(){
        setTimeout(() => {
            alert("Test alert"); 
        }, 100);
    }
}

tsonevn on 10 Apr 2018

👍4

All 2 comments

Hi @wanpeng2008,
In your scenario, you should way the UI to be loaded, before showing the alert. In this case, you can use ngAfterViewInit and set up timeout of 100 milliseconds, For example:

import { Component, OnInit } from "@angular/core";

import { Item } from "./item";
import { ItemService } from "./item.service";
import {Page} from "ui/page"
@Component({
    selector: "ns-items",
    moduleId: module.id,
    templateUrl: "./items.component.html",
})
export class ItemsComponent implements OnInit {
    items: Item[];

    constructor(private itemService: ItemService, private page:Page) {

     }

    ngOnInit(): void {
        this.items = this.itemService.getItems();
    }
    ngAfterViewInit(){
        setTimeout(() => {
            alert("Test alert"); 
        }, 100);
    }
}

tsonevn on 10 Apr 2018

👍4

Thanks @tsonevn . It works!

wanpeng2008 on 11 Apr 2018

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