Category: Technology - Page 12

Android: Basic WebView Tutorial

A WebView lets you pull a web page and display it in your Android app. It doesn’t take long to implement an Android WebView. Read on. I’ll show you how.

AndroidManifest.xml

First, open your manifest file to add this permission for INTERNET:

<uses-permission android:name=”android.permission.INTERNET” />

1	<uses–permission android:name=“android.permission.INTERNET” />

The web page won’t be loaded into your app without this permission.

This is how my manifest file looks like:

Path: ...\MyAndroidStudioProjects\WebView\app\src\main\AndroidManifest.xml

<?xml version=”1.0″ encoding=”utf-8″?>
<manifest xmlns:android=”http://schemas.android.com/apk/res/android”
    package=”net.catzie.webview” >
    <uses-permission android:name=”android.permission.INTERNET” />
    <application
        android:allowBackup=”true”
        android:icon=”@mipmap/ic_launcher”
        android:label=”@string/app_name”
        android:supportsRtl=”true”
        android:theme=”@style/AppTheme” >
        <activity android:name=”.MainActivity” >
            <intent-filter>
                <action android:name=”android.intent.action.MAIN” />
                <category android:name=”android.intent.category.LAUNCHER” />
            </intent-filter>
        </activity>
    </application>
</manifest>

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<?xml version=“1.0” encoding=“utf-8”?>

<manifest xmlns:android=“http://schemas.android.com/apk/res/android”

package=“net.catzie.webview” >

<uses–permission android:name=“android.permission.INTERNET” />

<application

android:allowBackup=“true”

android:icon=“@mipmap/ic_launcher”

android:label=“@string/app_name”

android:supportsRtl=“true”

android:theme=“@style/AppTheme” >

<intent–filter>

</intent–filter>

</activity>

</application>

</manifest>

activity_main.xml

Then we’re adding a WebView element to the XML file. My XML file is named activity_main.xml

Path: ...\MyAndroidStudioProjects\WebView\app\src\main\res\layout\activity_main.xml

<?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”
    />

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<?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”

/>

MainActivity.java

I have MainActivity.java here, which loads activity_main.xml and then loads a web page (google.com) into the WebView.

Path: ...\MyAndroidStudioProjects\WebView\app\src\main\java\net\catzie\webview\MainActivity.java

package net.catzie.webview;

import android.app.Activity;
import android.os.Bundle;
import android.webkit.WebView;

public class MainActivity extends Activity {
    private WebView webView;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        /**
         * WebView Begin
         */
        webView = (WebView) findViewById(R.id.webview);
        webView.getSettings().setJavaScriptEnabled(true);
        webView.loadUrl(“http://www.google.com”);
    }
}

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package net.catzie.webview;

import android.app.Activity;

import android.os.Bundle;

import android.webkit.WebView;

public class MainActivity extends Activity {

private WebView webView;

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

/**

* WebView Begin

*/

webView = (WebView) findViewById(R.id.webview);

webView.getSettings().setJavaScriptEnabled(true);

webView.loadUrl(“http://www.google.com”);

}

The following line of code attaches the WebView whose id is “webview” to the variable “webView”:

webView = (WebView) findViewById(R.id.webview);

1	webView = (WebView) findViewById(R.id.webview);

And this allows JavaScript in the WebView:

webView.getSettings().setJavaScriptEnabled(true);

1	webView.getSettings().setJavaScriptEnabled(true);

This one is what actually loads a given URl into the WebView:

webView.loadUrl(“http://www.google.com”);

1	webView.loadUrl(“http://www.google.com”);

February 29, 2016

PHP dynamic variable names tutorial

I think it’s very convenient for us developers, being able to name our variables dynamically. I’ll show you how to do it in PHP. 🙂

For example, we have variable $foo with “bar” as value like this:

<?php
$foo = “bar”;

1 2	<?php $foo = “bar”;

If we want to create a variable named based on the “value” of variable $foo, this is what we write:

<?php
$foo = “bar”;
$$foo = “My variable name is bar.”;
if(isset($bar)) echo $bar;

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<?php

$foo = “bar”;

$$foo = “My variable name is bar.”;

if(isset($bar)) echo $bar;

The echo should display: My variable name is bar.

Notice that the second variable that we declared was written as $$foo with 2 dollar symbols before the variable name. This makes it a variable variable — a variable whose name is a variable. What happens is that it first gets the value of $foo, which is “bar” and then uses that value as the variable name. And so, in the example above, defining the variable as $$foo = "My variable name is bar." is equal to defining it as $bar = "My variable name is bar.".

Making the PHP variable name more dynamic

Now, what if you want to make your variable name more dynamic? I’ll give you another example.

Here we are generating a random 1-digit number, we’ll use it later:

<?php
$numbers= array(1,2,3);

1 2	<?php $numbers= array(1,2,3);

The way that we’ll define the dynamic variables will be a bit different from the example earlier.

And here we have an array of strings:

<?php

$words = array(“uno”, “dos”, “tres”);

for($x=0; $x<sizeof($words); $x++){
	echo $words[$x];
}

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<?php

$words = array(“uno”, “dos”, “tres”);

for($x=0; $x<sizeof($words); $x++){

echo $words[$x];

}

What if we want to create variables whose names are based on the value of strings in the array, like $uno, $dos, and $tres?

We do it like in the code below. Notice that I defined my dynamically named variable like ${$v} inside the foreach:

<?php

$words = array(“uno”, “dos”, “tres”);

for($x=0; $x<sizeof($words); $x++){
	${$words[$x]} = “variable $” . $words[$x] . ” is defined! “;
}

if(isset($uno)) echo $uno;
if(isset($dos)) echo $dos;
if(isset($tres)) echo $tres;

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<?php

$words = array(“uno”, “dos”, “tres”);

for($x=0; $x<sizeof($words); $x++){

${$words[$x]} = “variable $” . $words[$x] . ” is defined! “;

}

if(isset($uno)) echo $uno;

if(isset($dos)) echo $dos;

if(isset($tres)) echo $tres;

Now let’s use the $numbers I showed you earlier. Pay attention to what I put inside the foreach.

<?php

$numbers= array(1,2,3);
$words = array(“uno”, “dos”, “tres”);

for($x=0; $x<sizeof($words); $x++){
	${$words[$x] . $numbers[$x]} = “variable $” . $words[$x] . $numbers[$x] . ” is defined! “;
}

if(isset($uno1)) echo $uno1;
if(isset($dos2)) echo $dos2;
if(isset($tres3)) echo $tres3;

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<?php

$numbers= array(1,2,3);

$words = array(“uno”, “dos”, “tres”);

for($x=0; $x<sizeof($words); $x++){

${$words[$x] . $numbers[$x]} = “variable $” . $words[$x] . $numbers[$x] . ” is defined! “;

}

if(isset($uno1)) echo $uno1;

if(isset($dos2)) echo $dos2;

if(isset($tres3)) echo $tres3;

The foreach let us define variables whose names are $uno1, $dos2 and $tres3, which are concatenated values from arrays $numbers and $words.

This is where the magic happens: ${$words[$x] . $numbers[$x]}

We combined elements from $words and $numbers arrays, then turned them into variable names by enclosing them in ${}

And that’s it! Use variable variables at your convenience. 🙂

February 19, 2016

PHP: get full URL of current page with GET params or without

The following string variable’s value will get the full URL of the current page, including GET arguments/params, if present.

<?php

$full_current_url = “http://” . $_SERVER[‘SERVER_NAME’] . $_SERVER[‘REQUEST_URI’];
echo $full_current_url;

?>

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<?php

$full_current_url = “http://” . $_SERVER[‘SERVER_NAME’] . $_SERVER[‘REQUEST_URI’];

echo $full_current_url;

?>

To get the full URL of current page but WITHOUT the GET args/params, do this instead:

<?php

$full_current_url = “http://” . strtok($_SERVER[‘SERVER_NAME’] . $_SERVER[‘REQUEST_URI’], “?”);
echo $full_current_url;

?>

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<?php

$full_current_url = “http://” . strtok($_SERVER[‘SERVER_NAME’] . $_SERVER[‘REQUEST_URI’], “?”);

echo $full_current_url;

?>

The strtok function will return only the part of the URL string up to the character before question mark “?” which is used by GET args/params.

strtok was suggested in this StackOverflow answer: http://stackoverflow.com/a/4643312

February 17, 2016

PHP: avoid backslash on json_encode

Hey! 🙂 If you are encoding your Arrays to JSON in PHP using json_encode() and the function adds backslash before your slashes, I’m gonna show you a quick fix.

This is my original code:

<?php
$arr = array();
$arr[‘success’] = true;
$arr[‘message’] = “Please enter email/phone number.”;
echo json_encode($arr);
?>

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<?php

$arr = array();

$arr[‘success’] = true;

$arr[‘message’] = “Please enter email/phone number.”;

echo json_encode($arr);

?>

And the result is:
{"success":true,"message":"Please enter email\/phone number."}

See the added backslash before the slash? Ugly, right? To avoid that, simply add the JSON_UNESCAPED_SLASHES argument to your json_encode() function usage like this:

echo json_encode($arr, JSON_UNESCAPED_SLASHES);

1	echo json_encode($arr, JSON_UNESCAPED_SLASHES);

Try it!

February 16, 2016

Android NetworkOnMainThreadException at StrictMode fix (with deprecated methods used)

A JSON Parser developed by some members of the Android dev team. But a few weeks after completion of the parser, several methods became deprecated.

And when we use that parser, we get errors. Part of the stack trace is as follows:

[…]
E/AndroidRuntime:  Caused by: android.os.NetworkOnMainThreadException
at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1148)
at java.net.InetAddress.lookupHostByName(InetAddress.java:405)
at java.net.InetAddress.getAllByNameImpl(InetAddress.java:251)
at java.net.InetAddress.getAllByName(InetAddress.java:229)
at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)
at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)
at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)
at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)
at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)
[…]

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[…]

E/AndroidRuntime: Caused by: android.os.NetworkOnMainThreadException

at android.os.StrictMode$AndroidBlockGuardPolicy.onNetwork(StrictMode.java:1148)

at java.net.InetAddress.lookupHostByName(InetAddress.java:405)

at java.net.InetAddress.getAllByNameImpl(InetAddress.java:251)

at java.net.InetAddress.getAllByName(InetAddress.java:229)

at org.apache.http.impl.conn.DefaultClientConnectionOperator.openConnection(DefaultClientConnectionOperator.java:137)

at org.apache.http.impl.conn.AbstractPoolEntry.open(AbstractPoolEntry.java:164)

at org.apache.http.impl.conn.AbstractPooledConnAdapter.open(AbstractPooledConnAdapter.java:119)

at org.apache.http.impl.client.DefaultRequestDirector.execute(DefaultRequestDirector.java:360)

at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:555)

at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:487)

at org.apache.http.impl.client.AbstractHttpClient.execute(AbstractHttpClient.java:465)

[…]

Not sure if the NetworkOnMainThreadException is being thrown because of the deprecated methods but the following code is what prevents our app from getting the error.

        StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
        StrictMode.setThreadPolicy(policy);

1 2	StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build(); StrictMode.setThreadPolicy(policy);

February 4, 2016

Android/Java: get variable data type

For some reason you might need to get the data type of your Java variable. Here’s an example of what you can try:

String date_created = “2016-02-04”;

String data_type = date_created.getClass().getSimpleName();

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String date_created = “2016-02-04”;

String data_type = date_created.getClass().getSimpleName();

Then do whatever you like with data_type, whose value should be “String”. 🙂

February 4, 2016

Get device’s IMEI in Android app development

Here’s the content of my MainActivity class where I log the IMEI of my test device.

package net.catzie.playground;

import android.content.Context;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.telephony.TelephonyManager;
import android.util.Log;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        TelephonyManager telephonyManager = (TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);
        String deviceID = telephonyManager.getDeviceId();
        Log.d(“Device IMEI”, deviceID);
    }
}

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package net.catzie.playground;

import android.content.Context;

import android.support.v7.app.AppCompatActivity;

import android.os.Bundle;

import android.telephony.TelephonyManager;

import android.util.Log;

public class MainActivity extends AppCompatActivity {

@Override

protected void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

TelephonyManager telephonyManager = (TelephonyManager)getSystemService(Context.TELEPHONY_SERVICE);

String deviceID = telephonyManager.getDeviceId();

Log.d(“Device IMEI”, deviceID);

}

You also need to add this permission to your AndroidManifest.xml file:

<uses-permission android:name=”android.permission.READ_PHONE_STATE” />

1	<uses–permission android:name=“android.permission.READ_PHONE_STATE” />

Place it inside the <manifest></manifest> tag, but same level as <application></application>.

Source: How to get the device’s IMEI/ESN programmatically in android?

February 3, 2016