One: String and StringBuffer difference
Two: The view, model, controller in Struts is the specific piece?
Three: How to instantiate the MAP interface?
Four: The difference between Map and HashMap?
Five: How to get the current date of the system, if you don't need a UITL package?
Six: What is the difference between List and ArrayList?
7: Define a polygon interface, requiring at least the number of polygons, perimeter and area by at least the interface. And achieve triangular, quadrilateral, rectangular, square. Building a polygon array containing these polygons and finds their perimeter and area of area. (Triangular area calculation formula: please answer
1. Talk about the difference between Final, Finally, Finalize. 2. Anonymous Inner Class (Anonymous Internal Class) Can IMPLEMENTS? 3.Static Nested Class and Inner Class are different, the more better, the more you are, the more you are, the more you have, the more you have. Some spreads) 4. The difference between collection and collections. 5.String s = new string ("XYZ"); create a few string object? 6.math.round (11.5) Is it equal to Math.Round (-11.5)? 7.Short S1 = 1; S1 = S1 1; What is wrong? Short S1 = 1; S1 = 1; What is wrong? 8. Sleep () and Wait () What is the difference? 9. Java has a goto? 10. A number of benes? This method? STRING has a length () method? 11. The difference between theOverLoad and Override. OverLoaded method can change the type of return value? 12. What is the difference between ERROR and EXCEPTION? 13.List, set, MAP inherits from a Collection interface? 14. What is the difference between 14.ABSTract Class and Interface? 15. If the interface can inherit the interface • Whether the abstract class can be implemented? Is the abstract class inherit the physical class (Concrete Class)? 16. Starting a thread is Run () or start ()? 17. Can you inherit the String class? 18. When one After the thread enters an Synchronized method of an object, whether other threads can enter this object? 19.Try {} has a return statement in Try {}, then keeping the code in the finally {} after this try or will not be Execute, before returna or after? 20. Programming: 2 multiplied by 8 equal to several? 21. Two object values (x.equals (y) == True However, there are different haveh codes, this sentence is not right? 22. When an object is passed as a parameter to a method, this method can change the properties of this object, and can return to change the result, then here Is the value delivery or reference delivery? 23. Swtich can function on Byte, whether it can act on long? 24. Garbage recycling mechanism, how to optimize the program? 25.java multi-thread programming. Write a multi-thread program with Java, write four threads, define a global variable i, two threads first to i plus 1, two threads to i minus one, output
