linux hardening

((Hello = = ("Hel" +lo) + "");9System.out.println (Hello = = ("Hel" +lo). Intern ());Ten } One } A classOther {StaticString Hello = "Hello"; } - PackageOther ; - Public classOther { Public StaticString Hello = "Hello"; } the true true true true false trueIn the same package, the reference is from the same string object.Under different classes of the same package, references are from the same string object.Under different packages, the same string object is still referenced from the same cl

implement multi-threading, in fact, after contact we will find that this is completely two different implementations of multi-threading, one is multiple threads to complete their own tasks , one is that multiple threads work together to complete a task .In fact, in the implementation of a task with multiple threads to do can also be used to inherit the thread class to achieve is just more trouble, generally we use the implementation of runnable interface to achieve, concise and clear.In most ca

// octal turns into decimal *String N6 = integer.valueof ("576", 8). toString (); $ System.out.println (N6); Panax Notoginseng //octal turns into binary -String N7 = integer.tobinarystring (integer.valueof ("23", 8)); the System.out.println (N7); + //octal turns into hexadecimal AString n8 = integer.tohexstring (integer.valueof ("23", 8)); the System.out.println (N8); + - $ //Binary goto decimal $String N9 = integer.valueof ("010110101010", 2)

1. Introduction of NiO (New io stream)JDK4 appears nio. The new IO and the traditional IO have the same purpose, are used for the input and output, but the new IO uses a different way to handle the input and output, in a memory-mapped file, the file or a section of the file map into memory, you can access the same memory as a visiting file, This is much more efficient than the old Io, but there are a lot of places where we see the old IO reference, so we still have the old IO as the primary, and

the game, or listening to music, the CPU is doing the program between the efficient switching let us feel that it is at the same time. 4. What is a thread ?multiple tasks can be performed within the same process, and each of these tasks I can see is a thread. thread: Is the execution unit of the program, the execution path. is the most basic unit of the CPU used by the program. Single Thread: If the program has only one execution path. Multithreading: If the program has more than one execution

value of the Value property on the S object A Char[] Value = (Char[]) valuefieldofstring.get (s); - //Change the 5th character in the array referenced by value -Value[5] = ' _ '; theSystem.out.println ("s =" + s);//Hello_world -}The printing results are as follows:1 s = HelloWorld2 s = Hello_worldIn this process,s always refers to the same string object , but before and after the reflection, the string object has changed, that is to say, by reflection, the so-called immutable object can

. Name.compareto (s.name): num; the //the name is the same length and content, does not mean the same age, so you have to continue to judge the age + intnum3 = Num2 = = 0? This. Age-s.age:num2; - returnnum3; $ } $}(2)Treesetdemo. Java:1 Packagecn.itcast_06;2 3 ImportJava.util.TreeSet;4 5 /*6 * Requirements: Please follow the name of the length of the order7 */8 Public classTreesetdemo {9 Public Static voidMain (string[] args) {Ten //To create a collect

(); thecomparableSuperk> k = (comparableSuperK>) key; + Do { AParent =T; theCMP =K.compareto (t.key); + if(CMP ) -t =T.left; $ Else if(CMP > 0) $t =T.right; - Else - returnT.setvalue (value); the} while(t! =NULL); - }WuyiEntryNewEntry(key, value, parent); the if(CMP ) -Parent.left =e; Wu Else -Parent.right =e; About fixafterinsertion (e); $size++; -modcount++; - return NULL; - }

()); //System.out.println (It.next ()); //The last one should not be written, so we should have a judgment before each acquisition//Judging whether there is the next element, there is to get it, not to ignore it//if (It.hasnext ()) {//System.out.println (It.next ()); // } //if (It.hasnext ()) {//System.out.println (It.next ()); // } //if (It.hasnext ()) {//System.out.println (It.next ()); // } //if (It.hasnext ()) {//System.out.println (It.next ()); // } //if (It.has

1. Use of the Aslist () method in the Arrays tool class1 Public static arrays into setsPrecautions:Although you can turn an array into a collection, the length of the collection cannot be changed .2. code example:(1)1 Packagecn.itcast_03;2 3 Importjava.util.Arrays;4 Importjava.util.List;5 6 /*7 * public static 8 * 9 * Precautions:Ten * Although you can turn an array into a collection, the length of the collection cannot be changed. One */ A Public classArraysdemo { - Public Static voi