Java interview questions
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Java is called a platform-independent programming language because it compiles source code into bytecode that can run on any platform with a JVM. The document also explains the use of the 'super' keyword, the differences between String and StringBuffer, methods of creating strings and threads in Java, and compares Java with C++. Key distinctions include Java's platform independence and the removal of complex features found in C++.
Java interview questions
- 2. Why is Java called Platform Independent programming Language? Java is a platform independent programming language because of the bytecode. Java compiler converts the source code into the bytecode which can be run on any platform where the JVM is available. This byte code is converted into the machine specific code by the Java Interpreter.
- 3. When is super keyword Used? 1. If we have to call the immediate parent class constructor we use the super keyword. 2. If we have to call immediate parent class method, we use super keyword. 3. super keyword is used to refer to the parent class instance variable.
- 4. What is the difference between StringBuffer and String? A String is an immutable class whereas StringBuffer is a mutable class. Immutable means unchangeable. String object can't change its content when it is once created but a new object is created. Mutable means content can be modifiable. we can change the content of StringBuffer object.
- 5. How we create a string in Java? If we are creating string object using the new keyword, JVM will store it into the Heap Memory. We can create a string in java by using two ways: 1. By using the new keyword.
- 6. 2. By using String literal. If we are creating string object using the String literal, JVM first checks its availability into the string constant pool. If it is already present in the pool, JVM creates just a reference to that string. If not present in the pool JVM will create a string in the string constant pool.
- 7. How we create a thread in Java? We can create Thread in Java by using two ways: By Extending a Thread class. By implementing Runnable interface.
- 8. what are the major differences between Java and C++? 1. Java is a platform independent language whereas C++ is a platform dependent programming language. 2. Java has removed many complex features like Explicit pointers, Operator overloading, Multiple- inheritance, Structure, Union etc. Whereas C++ supports all theses features.