java interview questions on strings

Introduction (excerpt from Java source code)Strings is constant; Their values cannot is changed after they is created.String buffers support mutable strings. Because String objects is immutable they can be shared.From this sentence, we can know that the string is an immutable object, the value of the object can not be changed. Because of this, the string is threa

; S1 + = 1; what's wrong?for short S1 = 1;S1 = s1 + 1; Because the type of the expression is automatically promoted by the s1+1 operation, the resultis an int, and then assigns a value to the short type S1, the compiler reports an error that requires a cast type.for short S1 = 1; S1 + = 1; since + = is a Java-language-defined operator, the Java compiler will treat it specially, so it compiles correctly.7, t

concepts of the Java programming language. Although they look similar, we don't care about these concepts as programmers, but they are different products for specific purposes. This is a common Java interview problem, and this article explains the concepts and gives the difference between them. 1) Java Development Ki

= mysql_query("SELECT * FROM user WHERE country = ‘China‘"); if0) { ... } // 有效率的： $r = mysql_query("SELECT 1 FROM user WHERE country = ‘China‘ LIMIT 1"); if0) { ... } 4. Jianjian Index for search wordsRefer to Java interview Preparation 15: Database--Index 5. Use a fairly typed example in the Join table and index itIf your application has many join queries, you should confirm that the fields of j

BAT Recruitment interview Java Technology 100 questions summary Too many questions, so just do the summary, do not answerAli School Recruit what is the parent class for all classes in 1.java. He has a way of doing it. What design pattern is applied to the InputStream under the IO package in 2.java. Please describe th

[LeetCode-interview algorithm classic-Java implementation] [014-Longest Common Prefix (Longest Common Prefix)], leetcode -- java [014-Longest Common Prefix (Longest Common Prefix )][LeetCode-interview algorithm classic-Java implementation] [directory indexes for all question

[LeetCode-interview algorithm classic-Java implementation] [067-Add Binary (Binary addition)], leetcode -- java [067-Add Binary (Binary addition )][LeetCode-interview algorithm classic-Java implementation] [directory indexes for all questions]Original question Given two bina

use R2 in addition to R1, ... So go on until you can divide it evenly. The last non-0 divisor is (A, b).Time complexity O (logn).String s = "a" + "B" + "C" + "D" + "E"; how many objects are created?1 of them. "A" is a constant and only the literal value is stored.What are the output results of the following programs?String str = "ABCDEFGH";System.out.println (str.dubstring (3,5));Answer: "DE"What's the difference between StringBuffer and StringBuilder?The newly introduced StringBuilder class is

For some personal reasons, we continued to participate in a number of school recruit recruitment, social recruitment of written and interview (BAT), also includes some foreign companies (Spotify, Google, Ericsson), and finally lucky to be netease income under the hands, got S. Here are some of my review of the main points, if you can use this as a reference, well prepared, domestic bat these companies of the basic technical test and

is 443. The HTTP connection is simple and stateless; The HTTPS protocol is a network protocol built by the SSL+HTTP protocol for encrypted transmission and authentication, which is more secure than the HTTP protocol. HTTP uses port 80 by default, HTTPS uses 443 port by default How HTTPS ensures the security of data transmissionHTTPS is actually in the TCP layer and the HTTP layer between the SSL/TLS to secure the upper layer, the main use of symmetric encryption, asymmetric encrypt

Explore strings, StringBuilder, and StringBuffer in JavaI believe that the string class is one of the most frequently used classes in Java, and it is a place that the major companies interview like to ask, and today come and learn about the string, StringBuilder, and StringBuffer classes, Analyze their similarities and differences and understand the scenarios tha

Java interview question summary and java question Summary1) What design patterns have you used? One by hand (except for a singleton); the factory mode, the facade mode (like the service layer); the proxy Mode 2) What is the core of springmvc, how is the request process handled and how is the reversal implemented? 1. The user sends the request to the front-end con

same; (2) If two objects have the same hashcode, they are not necessarily the same.Use the = = operator to check if the parameter is a reference to this object.45: Can I inherit the String class?The String class is the final class and cannot be inherited.46: When an object is passed into a method as a parameter, this method can change the properties of the object and return the changed result, is this a value pass or a reference pass?is a value pass. Method calls in the

Today to share the Java focus on the second part of the wrong point, but also the interview needs of all students to prepare, welcome to communicate correct.1. String creation and storage mechanism: When a string is created, it is first found in the constant pool whether the same string is already defined, based on the return value of equals of type string and, if defined, directly to the reference.You do n

In the Java interview, I always like a few questions about the String object, such: 1. String s = new String ("abc"); several String objects are created. 2. String s1 = "abc ";String s2 = "";String s3 = s2 + "bc ";String s4 = "a" + "bc ";String s5 = s3.intern ();If s1 = s3 is true or false, s1 = s4 is false or true. What about s1 = s5? I have encountered a lot of such questions. Today I would like to make a

Strings are also frequently used in programming.1) immutableIn fact, the view API will find:Public final class Stringextends objectimplements Serializable, ComparableFinal, immutable.public class TestString { static string upcase (String s) { return s.touppercase (); } public static void Main (string[] args) { String s = "BBC"; String SS = UpCase (s); System.out.println (s); }}Although the S-pass gives the UpCas

, thread synchronization, cannot be stored in NULL keys and null values. HashMap: The underlying is a hash table that allows null keys and null values, is not synchronized, is high efficiency TreeMap: The underlying is a two-fork tree, is unsynchronized, sortable, and is similar to set. The set bottom uses the Map collection. 3.Collection and map differences Collection: A single-column collection that saves one element at a time. Map: A two-column collection that has a pair of elements at a

Java and C common technical interview questions 2015 (Continuous updates ...), 2015 updating 1. Differences between overwrite and overload Overload is an Overload. It uses the same name as an existing member to declare attributes or methods, but the parameter list is different from that of the original member. Override is mainly used for method rewriting between the parent class and the subclass, that is,

, such as Java Class, Method, etc., and the garbage collector to collect the Java object is not very related. And the heapspace is divided into young generation and old generation of the young generation of garbage collection called the Youth GC, old generation garbage collection called Full GC. Objects that survived after N (configurable) garbage collection in the young generation are copied into the old g

Basic Java Learning (interview cookbook):What is the difference between the "= =" and the Equals method in 1.java?(1) The = = operator is specifically used to compare the values of two variables equal, that is, to compare variables stored in memory for the same value, to compare two basic types of data or two reference variables are equal, can only use the = = op