Java Reflection facilitate us to inspect classes, interfaces, fields and methods at runtime, without knowing the name of the classes, methods etc. at compile time.

The interface is a mechanism to achieve fully abstraction. There can be only abstract methods in interface, not method body. An Interface is also used to achieve multiple inheritance in Java.

If you are declared with abstract keyword of a class is called abstract class. It can have abstract and non-abstract method (method with body).

In java Inner class or nested class is declared inside the class or interface. We use inner class because it increases more readable & maintainable of code.

If you want to convert string to float,double,int,date and vice- versa then this article are very useful for that

If you are using more than one synchronized method in the program and want to access both synchronized method in a program on single thread.

Before JVM shuts down if you want to execute some code, use shutdown hook.

In java, Damon thread is a low priority thread .It is used for providing background support to any user thread to same process as the daemon thread.

if you have to read and write the textual information Then Java has suggested not to use the FileInputStream and FileOutputStream classes .

If we want to read data from multiple stream in java input/output operation then SequenceInputStream class is very useful for that.

If we don’t know how many arguments we will have to pass in the method .Varargs is the better approach.

In Java, Their are several ways to taken an input from the keyboard.such like InputStreamReader Class,Scanner class,Console class etc.

Serialization is a process of converting an object into a stream.

The Java Console class is often using to get input from console. It provides methods to read text and password.

The StreamTokenizer class allows you to break an input stream into tokens such as words.

Regular Expression used to define constraint on strings such as password and email validation.

By Default, the Object class is the parent class of all the classes in java or we say, it is the topmost class of java.

A BLOB is a build-in data type supported by the database implementing SQL 99 alias SQL3 Standards. A BLOB is used to store large binary data ,such as bit images,audios,and multimedia clips as the column value in a database table.

A cursor defines the runtime execution environment for query when the result of the query execution can be captured.

In Java, CallableStatement is used to call the stored procedures and functions by using an object of the CallableStatement Interface.

Synchronization is required when more than one thread sharing the same resources .

As I said, there could be many possible answer of this question, and only designer of String class can answer it with confidence