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Showing posts from November, 2019

JDBC – PreparedStatement– How to Set Null value?

Introduction Java Database Connection (JDBC) API allows the Java programmers to access different relational and NoSQL databases like Oracle, MySQL, SQL Server, etc. It helps to store, access and manipulate the data stored in these databases. In this post, we will explore how to set the NULL values in PreparedStatement. Null String data type For String data type, it does not matter if the value to be set as a parameter in the SQL query is NULL.   Other data types like Integer, Float, Double, Date, etc. For data types like Integer , Float , Double , Date we have to explicitly call the setNull method. Example String name = null ; Long id = null ; PreparedStatement ps = connection.prepareStatement("select * from person where first_name = ? and id = ?");  ps.setString(1,name); The above line will execute without throwing any exception ps.setLong(2, id); In the above line of code, since id is null, it will throw java.lang.NullPoi

Apache Maven - How to set network proxy settings?

In the following post, we learned how to install Apache Maven on Windows 10 How to install Apache Maven on Windows? If your development PC is behind a proxy network, you will not be able to add Java dependencies through Maven. Luckily Maven provides us with proxy settings. Add your network proxy to Maven's proxy settings STEP 1:  Navigate to your maven's directory and open conf folder E:\apache-maven-3.6.2\conf STEP 2:  Open settings.xml in your favorite text editor STEP 3: Uncomment the proxy tag inside proxies tag and add the values according to your network's proxy settings. <proxy>       <active>true</active>       <protocol>http</protocol>       <username>proxyuser</username>       <password>proxypass</password>       <host></host>       <port>80</port>       <nonProxyHosts>|</nonProxyHosts>     </proxy>

How to install Apache Maven on Windows 10?

Apache Maven is a Java tool that helps in building and managing the Java project. It is based on the concept of Project Object Modle(POM). It helps the Java developers to manage the project's JAR files in a central repository and those JAR files can be shared across the project. Maven project has the following objectives makes the build process easy provides a uniform build system  and many more In this post, we will learn how to install the Apache Maven on Windows (10). STEP 1: Download and install Java Download Java from . and install it. STEP 2: Download Apache Maven Download Apache Maven from  and extract it on your local machine like I have unzipped it to  E:\apache-maven-3.6.2 STEP 3: Set the JAVA_HOME environmental variable Right Click This PC ->  Properties -> Advanced system settings -> Environmental Variables Open Environmental Variables Click on N

How to convert a String to int in Java?

Introduction In this post, we will learn to convert String to int primitive data type. Java provides the Integer wrapper class to convert a String to int. Integer.parseInt(String) String numberString = "134"; int number = Integer.parseInt(numberString ); System.out.println(number); Output : 134 Integer.valueOf(String) String numberString = "134"; int number = Integer.valueOf(numberString ); System.out.println(number); Output : 134 The following code will throw NumberFormatException //134a cannot be converted to Integer String numberString = "134a"; int number = Integer.valueOf(numberString ); System.out.println(number); Exception in thread "main" java.lang.NumberFormatException: For input string: "134a" at java.lang.NumberFormatException.forInputString(Unknown Source) at java.lang.Integer.parseInt(Unknown Source) at java.lang.Integer.valueOf(Unknown Source) at StringExample.main(StringExample

Top 10 mostly asked Java String Interview Questions

Introduction String is the most widely used class in any language. In this post, we will explore String in Java context. This post will help you to understand the String in-depth and to answer String related questions in a Job interview. 1. What is String? String is a final class in Java and not a primitive data type like int, float, etc. It is defined in java.lang package and therefore available by default. 2. How to create objects of String? There are two ways to create String a. String literals String str = "abc"; b. Using new operator String str = new String("abc"); 3. Where is String stored in memory? String literals are stored in the String constant pool. A string is called immutable or constant i.e. once created then it can not be changed. Whenever we create a String using double quotes (String literal), Java looks into the String constant pool if an object with the same value is present, it returns the reference to that object