logger class in java

Personal understanding of Java Reflection: Reflection is a set of methods for understanding classes and using classes ; The Java basics know how to instantiate a class, and also know how to invoke a variable or method through an instance;But many times the class is not written by ourselves, so we do not know the

the results, the static variables of Java are executed only when the class is first loaded and initialized.2. Class variables do not depend on instances of classes, and class variables are allocated only once in the stack memory at initialization time, no matter how many instances of the

()]; Is.read (b); returnDefineClass (name, B, 0, b.length); } Catch(IOException e) {Throw Newclassnotfoundexception (name); } } }; Object obj= Myloader.loadclass ("Com.classload.temp.MainTest"). newinstance (); System.out.println (Obj.getclass ()); System.out.println (objinstanceofcom.classload.temp.MainTest); /*** Execution Result: * Class Com.classload.temp.MainTest * false/ /obj uses the M

　　In Java code, people assume that only one return value or no return can be returned in a method. Bloggers in the development process encountered such a situation, the Android client request data, the background may return two results (1) Access token invalidation, no data returned. (2) normal access to data.　　In such cases, it is necessary to determine whether there is data return based on the access token identity. Returns the user login prompt whe

After some time in Java learning, you may often hear the word reflex, which means that Java has learned a higher level. Next, I'll take a step-by-step with you to uncover the mysteries of Java's advanced features reflection.The concept of the following class object is introduced first, and may often be used in this concept:　　　　

Java File class learning notes 2: File class objects and common operation methods, file learning notes 1. File, relative path, and absolute path 1. File(1) standard files: such as images and music files.(2) directory file: a folder.(3) virtual memory files: temporary files generated by the system during program running. 2. File Path(1) Relative Path: compared wit

[JAVA] java enumeration class, java Enumeration I. Under what circumstances do I use enumeration classes? Sometimes the objects of a class are limited and fixed. In this case, it is more convenient to use enumeration classes? 2. Why not use static constants to replace enumer

are freed, but the object allocated in the heap is not reclaimed, and the local variable lincintf in the main method points to it ;There's no problem here, but in line 27th, lincintf calls the test method, and the test method accesses the local variable A in the member method Localinclassre, and a does not exist at this time, so an error occurs;That is, local variables are different from the life cycle of the objects of local inner classes;To solve this problem,

(); In.print (); }}4. Method inner Class (local inner Class) = = = "Understanding can be said to be infrequently usedMethod Inner class cannot be decorated with a restriction (such as public)Class out { private int: age = n; public void Print (final int ×) {

In Java, the StringTokenizer class separates strings, and the string class separates strings. This class is rarely used and is not recommended in the API documentation. RecommendedStringOfSplitMethod or java. util. regex package. import java.util.StringTokenizer;public

{private String name = "Zhang San";p rivate int num1 = 1;public void outer () {System.out.println (name+ "" +num1);//syst Em.out.println (num2); The outer class cannot directly access the Inner class member Inner1 Inner1 = new Inner1 ();//The outer class can instantiate an inner class, access the Inner

does not define final, then when the outer class method executes, The local variable must be gc, but a method of the inner class has not been executed, and the external variable that he refers to cannot be found. If defined as final,java, this variable is copied as a member variable inside the inner class, so that the

The inner class of the member means that the bread in an outer class has a non-static class, for example:class outerclass{ // variables, function definitions ... class innerclass { // variable, function definition ... }} About the various uses of the members ' i

total instance object of classSystem.out.println (c1==C2); //The Third Way of expressionClass c3=NULL; Try{C3=class.forname ("Com.reflect.Foo"); } Catch(ClassNotFoundException e) {e.printstacktrace (); } System.out.println (C2==C3); //We can create instance objects of the class--> by the class type of the class, by creating an instance of Foo by C1 or C2 or C3.

1. Class LoaderMultiple ClassLoader can be installed in a Java virtual machine, and the system defaults to the main three classloader, each of which is responsible for loading the class at a particular location: BootStrap (embedded in the Java virtual machine, written in C + +), Extclassloader,appclassloader. Of course

Packagecom. buckupDB; importjava. io. BufferedReader; importjava. io. File; importjava. io. FileInputStream; importjava. io. Fil Package com. buckupDB; import java. io. BufferedReader; import java. io. File; import java. io. FileInputStream; import java. io. Fil Package com. buckupDB; Import

* @param x * @return */public static byte inttobyte (int x) {return (byte) x; }/** * byte to int * @param b * @return */public static int Bytetoint (byte b) {//java byt E is signed, converted to unsigned return B 0xFF via 0xff; }/** * byte[] to int * @param b * @return */public static int bytearraytoint (byte[] b) { Return b[3] 0xFF | (B[2] 0xFF) The most comprehensive

to the same object is true, only two objects that have a parent-child or peer relationship can be compared1System.out.println (NewInteger (1). Equals (NewInteger (1)));//true2 //because the integer compares the value, the integer class overrides the Equals method of the parent class of the object class3 //the method of the integer class aft

[Java class set] _ identityhashmap class notes In normal map operations, the key itself cannot be repeated. Import Java. util. map; import Java. util. hashmap; import Java. util. iterator; import