Category: Java

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);
    }
}

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

Android: open web page in a browser

To open a web page in an Android app, we need to create a new Intent and start a new Activity with it.

Here’s a Java method that we can re-use:

private void goToUrl (String url) {
        Uri uriUrl = Uri.parse(url);
        Intent launchBrowser = new Intent(Intent.ACTION_VIEW, uriUrl);
        startActivity(launchBrowser);
}

private void goToUrl (String url) {

Uri uriUrl = Uri.parse(url);

Intent launchBrowser = new Intent(Intent.ACTION_VIEW, uriUrl);

startActivity(launchBrowser);

}

Just pass the URL of the web page you’d like to open to this method.

Source: How to open a website when a Button is clicked in Android application?

January 29, 2016

Android / Java: Get the name of method being executed

If you want to trace the name of the method that’s being executed, the Java code snippet in this page might help you.

This is especially handy when you are debugging by tracking every method that is executed. You can enclose these lines of codes in a function that you call in every method — that’s easier than typing the name for each method you’re tracking, right? 🙂

The String variable methodName will contain the name of the method where you place the following lines of code:

Java

String methodName = new Object(){}.getClass().getEnclosingMethod().getName(); Log.d(“Executed Method”, methodName);

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String methodName = new Object(){}.getClass().getEnclosingMethod().getName();
Log.d(“Executed Method”, methodName);

January 26, 2016

Android: underline text in your app

When I need to underline text in an app that I’m developing, I like doing it programmatically. The code is in the Java file, not in the XML.

Maybe we should make a function for this where we pass the ID of the TextView whose content we’d like to underline.

        TextView myTextView = (TextView) findViewById(R.id.myTextViewID);
        String htmlString = “<u>” + myTextView.getText() + “</u>”;
        myTextView.setText(Html.fromHtml(htmlString));

TextView myTextView = (TextView) findViewById(R.id.myTextViewID);

String htmlString = “<u>” + myTextView.getText() + “</u>”;

myTextView.setText(Html.fromHtml(htmlString));

Disadvantages in this method:

It’s done in the Java file, not in UI files such as XML. It makes more sense to add codes for styling in XML files to me.
This underlines all text in the TextView. What if we need to underline only one text in a paragraph?

If you have any suggestion, feel free to comment. 🙂

// EDIT:

Here’s a method I prepared to make underlining TextView values easier:

public void setTextViewUnderline(TextView myTextView){
String htmlString = “” + myTextView.getText() + ““;
myTextView.setText(Html.fromHtml(htmlString));
}

January 21, 2016

Java: Strings

First off, if you are in need of a good Java programming reference book, I suggest that you try Head First Java.

In this blog entry, basics in Strings in Java programming will be briefly discussed.

Assumption: You have already set up your Java development kit on your computer. (Environmental Variables, paths, etc…)
(more…)

March 29, 2011
PDF Download: Head First Java (2nd Edition) – by Katy Sierra and Bert Bates
Learning Java? Great, this book will help you.

I uploaded this Java Programming PDF to share with IT Elective 1 (Object Oriented Programming with Java) classmates. 🙂

I searched for it in Google, and I’m lucky to find this free e-book of Head First Java – Second Edition. I can’t remember where I got it from though. It’s been days (EDIT: no, it’s been months now! or maybe years), and I got a poor memory. lol.

And by the way, I used A-PDF Split to split the e-book into separate chapters of the PDF for our convenience. The file I downloaded is only one PDF file which had 690 pages. It lags in slow computers. It’s also better off being separated by chapters for ease of reading, right? So, there. 😀

I hope the Java PDF download links on this blog entry (Head First Java – Download) help you guys, and if you do find them helpful, please LIKE my website on Facebook. To find it on Facebook, search for “Catzie.net” 😀

Download Link for Head First Java Ebook

New! The following Head First Java Ebook is of better quality than the scanned one. It’s not split into several PDFs of individual chapters though, because I have no time to do it yet. It’s one big PDF file for now.

FILE SIZE: 37.53MB

Head First Java (2nd Edition, Better Quality in One Big PDF) by Kathy Sierra and Bert Bates (Non-hotlinked from MediaFire) (unknown, 6,136 hits)

Download Links for Head First Java Ebook

The zip file that follows contains Head First Java scanned ebook split into several PDFs of individual chapters.
FILE SIZE: 31.6MB
- Head First Java (2nd Edition, Scanned) by Kathy Sierra and Bert Bates (Non-hotlinked from MediaFire) (unknown, 2,418 hits)
- Head First Java (2nd Edition, Scanned) by Kathy Sierra and Bert Bates (on FileDen) (unknown, 1,639 hits)
Java Book Chapters
1. Breaking the Surface: a quick dip
2. A Trip to Objectville: yes, there will be objects
3. Know Your Variables: primitives and references
4. How Objects Behave: object state affects method behavior
5. Extra-Strength Methods: flow control, operations, and more
6. Using the Java Library: so you don’t have to write it all yourself
7. Better Living in Objectville: planning for the future
8. Serious Polymorphism: exploiting abstract classes and interfaces
9. Life and Death of an Object: constructors and memory management
10. Numbers Matter: math, formatting, wrappers, and statics
11. Risky Behavior: exception handling
12. A Very Graphic Story: intro to GUI, event handling, and inner classes
13. Work on Your Swing: layout managers and components
14. Saving Objects: serialization and I/O
15. Make a Connection: networking sockets and multithreading
16. Data Structures: collections and generics
17. Release Your Code: packaging and deployment
18. Distributed Computing: RMI with a dash of servlets, EJB, and Jini
Happy Java programming, y’all. 🙂 Make good use of the learning Java book you downloaded.

Java is a programming language originally developed by James Gosling at Sun Microsystems (which is now a subsidiary of Oracle Corporation) and released in 1995 as a core component of Sun Microsystems’ Java platform.

The syntax of Java is mostly derived from that of C and C++ programming languages, but with simpler object model and fewer low-level facilities.
September 16, 2009

Category: Java

Download Link for Head First Java Ebook

Download Links for Head First Java Ebook

Java Book Chapters