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How-to articles, tricks, and solutions about JAVA

Adding header for HttpURLConnection

To add a header to an HTTP request using HttpURLConnection, you can use the setRequestProperty method.

java http

Android changing Floating Action Button color

To change the color of a Floating Action Button (FAB) in Android, you can use the setBackgroundTintList() method and pass it a color state list.

java android android-5.0-lollipop floating-action-button

android on Text Change Listener

In Android, you can use a TextWatcher to listen for changes to the text in a TextView or EditText view.

java android textview onchange

Android SDK installation doesn't find JDK

If the Android SDK installation is unable to find the JDK (Java Development Kit), it could be because the JDK is not installed or is not installed in the default location.

java android sdk windows-7-x64 jdk6

Android Split string

To split a string in Android, you can use the split() method of the String class.

java string android

Any shortcut to initialize all array elements to zero?

To initialize all elements of an array to zero in Java, you can use the Arrays.fill method from the java.util package.

java

Append a single character to a string or char array in java?

To append a single character to a string or char array in Java, you can use the + operator or the concat method for strings, or you can use the Arrays.copyOf method for char arrays.

java string append

ArrayList of int array in java

To create an ArrayList of int arrays in Java, you can use the following syntax:

java arraylist

Avoiding NullPointerException in Java

A NullPointerException is a runtime exception that is thrown when an application attempts to use an object reference that has a null value. To avoid this exception, you need to make sure that the object reference is not null before you use it.

java null nullpointerexception

Base64 Java encode and decode a string

To encode and decode a string in Base64 in Java, you can use the java.util.Base64 class.

java base64 decode encode