Develop Reference

Adding code to bottom navigation android studio

I have made a simple app using Android Studio with bottom navigation. It all works well until I add code to the Fragments. Where is the place I need to add code in this example?
This part is written in the activity of a fragment. I have placed the variables in Public Class, and wanted to write the code in "public void onCreate", but the app crashed if I try to write anything there (even the most basic like declaring a variable).
My question is: in which part I should write the code? I am trying to put a simple Timer on this Fragment.
Hope my question is clear this time, first time posting here.
package com.example.testfitnessapp;
import android.os.Bundle;
import android.os.Handler;
import android.os.SystemClock;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;
import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.fragment.app.Fragment;
public class TrainingFragment extends Fragment {
Button start, pause, reset;
View textView;
Handler handler;
#Nullable
#Override
public View onCreateView(#NonNull LayoutInflater inflater, #Nullable ViewGroup container, #Nullable Bundle savedInstanceState) {
super.onCreateView(inflater, container, savedInstanceState);
return inflater.inflate(R.layout.fragment_training, container, false);
}
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// do your variables initialisations here except Views!!!
}
public void onViewCreated(View view, Bundle savedInstanceState){
super.onViewCreated(view, savedInstanceState);
// initialise your views
}
}

I am trying to put a video(mp4) in the app but it is not playing

package com.example.video_app;
import androidx.appcompat.app.AppCompatActivity;
import android.net.Uri;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.VideoView;
public class MainActivity extends AppCompatActivity {
Button clk;
VideoView Videov;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
clk=(Button)findViewById(R.id.button);
Videov=(VideoView)findViewById(R.id.videoView);
}
public void videoPlay(View v){
String videoPath="android.resource:// com.example.video_app/"+R.raw.sv;//video path
Uri uri= Uri.parse(videoPath);
Videov.setVideoURI(uri);
Videov.start();//start
}
}
I am new to android studio trying to build a simple app of video playing but the video is not playing cant get where the problem is.The video is not playing on emulator nor on my phone. i have tried all the codes mentioned in stackoverflow but could not find any solution... help to resolve this problem

Check out OnPreparedListener. Call start() from inside that event, since then the file will be ready to be played.

You haven't called videoPlay() method from any of the method,
Call videoPlay() method from onCreate() after findViewById() of video view.
and remove View v from videoPlay() method,i think it's useless.

How can I calling JavaScript in WebView from Android?

I am beginner in Android development and want to create Android app with JavaScript.
I can run my page in WebView.
I can run JavaScript in WebView.
I can call Android Toast message (or Dailog alert ) from JavaScript to Android.
But I can NOT run JavaScript function from Android !
Can you help me to fix my code
[ Download an android studio project ]
http://r7eq.weebly.com
Code of MainActivity.java
package com.example.adnroid_script;
import android.app.Activity;
import android.os.Bundle;
import android.webkit.WebView;
import android.webkit.JavascriptInterface;
import android.widget.Toast;
public class MainActivity extends Activity {
public static WebView myWebView = null;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
myWebView=(WebView) findViewById(R.id.webview);
myWebView.getSettings().setJavaScriptEnabled(true);
myWebView.addJavascriptInterface(new jsInterface(), "FromJS");
myWebView.loadUrl("file:///android_asset/index.html");
}
public class jsInterface{
#JavascriptInterface
public void ToAndroid(String jsMessage){
Toast toast = Toast.makeText(getApplicationContext(),"I sent javascript code to myWebView", Toast.LENGTH_LONG);
toast.show();
WebView myWebView = (WebView) findViewById(R.id.webview);
// ### The bug is here ### //
myWebView.loadUrl("javascript:document.write('<div>Android say : It is working now !</div>');");
}
}
}

Android Javascript Interface empty object in webview

I am trying to set up a simple Android app that displays a webview and has some extra functionality available via the Javascript Interface.
I am testing on a HTC One S running Kitkat (via Cyanogenmod). When I inspect the webview the object inserted (Android) is empty "Object {}". I cannot use the functions in the interface via the loaded page.
I had built a more complicated activity but could not get the interface working, so I've created this new app for testing which contains the only the code from the webview guides. Still not inserting the methods into the exposed object.
MyActivity
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.webkit.WebSettings;
import android.webkit.WebView;
public class MyActivity extends Activity {
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
WebView myWebView = (WebView) findViewById(R.id.webview);
myWebView.addJavascriptInterface(new WebAppInterface(this), "Android");
WebSettings webSettings = myWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
myWebView.loadUrl("http://47e148ba.ngrok.com");
}
#Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.my, menu);
return true;
}
#Override
public boolean onOptionsItemSelected(MenuItem item) {
// Handle action bar item clicks here. The action bar will
// automatically handle clicks on the Home/Up button, so long
// as you specify a parent activity in AndroidManifest.xml.
int id = item.getItemId();
if (id == R.id.action_settings) {
return true;
}
return super.onOptionsItemSelected(item);
}
}
WebAppInterface
import android.content.Context;
import android.webkit.JavascriptInterface;
import android.widget.Toast;
/**
* Created by graeme on 28/08/2014.
*/
public class WebAppInterface {
Context mContext;
/** Instantiate the interface and set the context */
WebAppInterface(Context c) {
mContext = c;
}
/** Show a toast from the web page */
#JavascriptInterface
public void showToast(String toast) {
Toast.makeText(mContext, toast, Toast.LENGTH_SHORT).show();
}
}
Layout
<?xml version="1.0" encoding="utf-8"?>
<WebView xmlns:android="http://schemas.android.com/apk/res/android"
android:id="#+id/webview"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
/>
build.gradle
apply plugin: 'com.android.application'
android {
compileSdkVersion 19
buildToolsVersion "20.0.0"
defaultConfig {
applicationId "com.mydomain.jswebview"
minSdkVersion 17
targetSdkVersion 19
versionCode 1
versionName "1.0"
}
buildTypes {
release {
runProguard false
proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
}
}
}
dependencies {
compile fileTree(dir: 'libs', include: ['*.jar'])
}
You can see I'm using the decorator required for the methods, which most questions seem to have as the solution. I'm developing in Android Studio if any of the presets in there might be interfering?
Edit:
In The JS file, or via the console if I'm inspecting the webview via chrome if I call Android or window.Android i get an empty objected returned "Object {}". Or if I try to use the methods defined in the interface above I'll receive a method undefined error.

I was having the same problem. Turned out to be a Proguard problem. Try adding the following to your Proguard rules:
-keepclassmembers class ** {
#android.webkit.JavascriptInterface <methods>;
}

I don't know how are you trying to call to your Java methods from inside of your WebView. I think that the correct way is:
javascript:window.Android.showToast('Hi!');
you could also test your JS interface from your Java code using:
myWebView.loadUrl("javascript:window.Android.showToast('Hi!');");
I hope this help you!

android webview bind javascript to android code

Hi i'm setting up my first webview app in android and i try to make my javascript code calls the android code according to this tutorial :
http://android.programmerguru.com/binding-javascript-and-android-code-example/
What i'm trying exactly to do is to play a sound on an onclick event like in my website but it's pretty slow and i read many post on it and i understood why i should use another way to do that.
As i found the tutorial i put in the previous link, i tried to make it work in this way but nothing happened. I create "raw" folder and put in it "click.mp3" file.
I'm probably forgetting something but i don't find it...
MyActivity.java files:
package com.example.mywebviewapp;
import android.media.MediaPlayer;
import android.app.Activity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.webkit.WebSettings;
import android.webkit.WebView;
public class MyActivity extends Activity {
private WebView mWebView;
MediaPlayer mysound;
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my);
mWebView = (WebView) findViewById(R.id.activity_main_webview);
// Enable Javascript
WebSettings webSettings = mWebView.getSettings();
webSettings.setJavaScriptEnabled(true);
//Inject WebAppInterface methods into Web page by having Interface name 'Android'
mWebView.addJavascriptInterface(new WebAppInterface(this), "Android");
mWebView.loadUrl("http://mywebsite.com");
}
public class WebAppInterface{
public void soundAndroClick(){
mysound = MediaPlayer.create(MyActivity.this, R.raw.click);
mysound.start();
}
}
}
and i call the method soundAndroClick() in my main.js file like that:
function soundAndroid(){
Android.soundAndroClick();
}