1) Static blocks/static methos/static variables are executed first in the order of thier appearance in the code.
After executing static's instance blocks/instance methos/instance variables are executed.
2) The reference may be null when calling a static method from main method.
3) float arr[][] = new float[][10]; is wrong
float arr[][] = new float[10][]; is correct
4) WaitNotify(){} in a class in not private but public
5) An integer type data can't be assigned to char type because of negative range of integer data.
6) StringIndexOutOfBoundsException is thrown if the loweIndex < 0 or upperIndex > string.length or upperIndex < lowerIndex for subString method of String class.
7) Interfaces cannot have constructors but abstract classes can.
8) Private variables are available though instances even to the main method within the same class.
9) when both the String and Object argument constructors are considered by the compiler for eligibility, the compiler will choose the 'Most specific method.