Java is one of the best high-level languages which most programmers use for developing products and testers use for automation. Also, almost 65% of the modern automation solutions use Java as their backbone. Hence, the Interviewers usually ask questions on important Java topics like Java basics, Java Collection Quiz, Java String Quiz, and Java Threading Quiz. And every software tester needs to get him/herself well-versed in these areas to succeed in testing job interviews. To help them, we bring a comprehensive list of Java interview questions so that they can confidently answer anything related to Java asked by the Interviewers.
It took us a while to come up with such a diverse set of Java interview questions. And it helped many of readers in the Software testing fraternity to gain confidence in Java skills. We know that there are a lot of testers who write quality Java code. But, they don’t focus on the theoretical part that is what required to clinch a top Software testing job interview. We hope this post would quickly help them filling this gap, and they would be able to learn just more than coding. Let’s now find out which of the Java interview questions is going to help you in the interviews.
JVM stands for The Java Virtual machine. It translates and executes the Java bytecode. Its the entity which transforms Java to become a “portable language” (i.e., write once, run anywhere). Though, each platform has its implementation of JVM like the Windows, Linux, macOS, etc. have a distinct version of JVM to run bytecode.
Its certainly possible to have multiple main methods in different classes. When you start the application, youve to provide the startup class name for execution. The JVM then looks up for the main method only in the class whose name youve supplied. Hence, you wont observe any conflict with the multiple classes having the
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Top 25 Java Interview Questions and Answers for SDET
25. What is String in Java?
String in Java is an object that represents sequence of characters. An array of characters works same as Java string. String in Java is an immutable (cannot grow) object that means it is constant and cannot be changed once it is created.
16. What is Polymorphism?
Polymorphism allows us to perform a task in multiple ways. Let’s break the word Polymorphism and see it, ‘Poly’ means ‘Many’ and ‘Morphos’ means ‘Shapes’. Read more here
Assume we have four students and we asked them to draw a shape. All the four may draw different shapes like Circle, Triangle, and Rectangle.
23. What is Interface in Java?
An interface in Java looks similar to a class but both the interface and class are two different concepts. An interface can have methods and variables just like the class but the methods declared in interface are by default abstract. We can achieve 100% abstraction and multiple inheritance in Java with Interface. Read more on Interface in Java.