Java class Library (Java.lang) package overview

1. Interface java.lang.Appendable an append (append) interface. The object instance of the class that implements the interface has the ability to append characters or sequences of characters to it. Classes that want to be able to receive formatter output must implement the interface. Java.lang.CharSequenceCharSequence refers to a sequence of readable characters. This interface provides a uniform method for read-only access to various types of character sequences. Java.lang.Cloneable can be cloned interface. The class that implements the interface has the ability to clone. You can copy the domain (field) of an instance object of a class to another instance of the same class by using the Object.clone () method. If you use the Object.clone () method to clone an instance object of a class that does not implement the interface, a clonenotsupportedexception exception is triggered. Java.lang.Comparable can compare interfaces. A comparison can be made between two instance objects of the class that implements the interface. The comparison results of negative numbers (-1), 0, positive numbers (1) respectively represent the relationship between the comparison object and the object being compared is less than, equal to, or greater than. You can sort multiple instance objects of a class that implements the interface. Java.lang.Iterable an iterative interface. Classes that implement this interface are generally used as containers and have the ability to provide sequential access to the functionality of the object being contained. Java.lang.Readable can read the interface. A client object can read characters from an instance object in the class that implements the interface. Java.lang.Runable can run interfaces. The instance object of the class that implements the interface will be run in a separate thread (thread). Classes that do not have an extension thread can develop the ability to create multithreaded services by implementing this interface. The Java.lang.Thread.UncaughtExceptionHandler thread did not capture the exception controller interface. When an exception is thrown during thread execution and is not captured, the class that implements the interface can handle the condition as a controller.

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2. Class Java.lang.Boolean The class that initializes the original data type. The instance object of the class, in addition to containing a Boolean value, provides a way to handle a Boolean, such as converting between Boolean strings. A class that java.lang.Byte the original data type byte. An instance object of this class, in addition to containing a byte value, provides a way to handle byte, such as converting between byte and other types. Java.lang.Character A class that converts the original data type char to an object. The instance object of the class provides a way to handle characters in addition to a char value. The Java 2 platform uses UTF-16 expression characters in character arrays, strings, or StringBuffer. UTF-16 uses 16 to 21 bits of bits expression, from/u0000 to/U10FFFF. /u0000 to/UFFFF represents basic 16-bit characters,/u10000 to/U10FFFF for auxiliary characters (supplymentary characters). Auxiliary characters are composed of a high level substitution character (high-surrogate) and a lower substitution character (low-surrogate). A high-level substitution uses a character representation between a/ud800 and a/udbff, and a lower-level substitution uses a character representation between a/udc00 and a/udfff. Suppose: A represents the code point value of the auxiliary character (SC), B represents the code point of the high substitution of SC (Unicode code points), and C represents the code point value of the lower substitution character for SC. So the following equation is set up: A = (b-0xd800) << + (C-0XDC00) + 0x10000 when restoring Unicode to a readable character, the two consecutive characters are interpreted when and only if the current character is a high substitute and the next character is a low substitute. As a secondary character. Java.lang.Character.Subset the instance of the class to express a specific subset of a Unicode character set. Java.lang.Character.UnicodeBlock the instance object of the class to express a family of related child Unicode character sets. These child character sets usually serve the same purpose. Java.lang.Class the instance object of the class to express the class or interface that is running in the Java application. This class does not have a public construction method, so it cannot be instantiated automatically by the Java virtual machine, but by ClassLoader. Java.lang.ClassLoader This class is the Java class loader, which is responsible for loading the corresponding class based on the binary name that is developed. In the Java languageThe specification stipulates that there are three kinds of names for classes, interfaces, or raw data types, they are the license name (fully qualified name), the canonical name (canonical name), the binary name (binary name). Different class loaders read the binary class "*.class" information from different sources according to the binary name of the class and generate a Class object. Each class has a reference to its loader.

package org.javaplus.jdkoverview;
public class OuterClass {
public class InnerClass {
public InnerClass() {}
}
public OutterClass() {}
}
public class SubClass extends OuterClass {
public SubClass() {}
}

Name License name of the Org.javaplus.jdkoverview.SubClass internal class (Innerclass):

Org.javaplus.jdkoverview.SubClass.InnerClass Specification Name:

Org.javaplus.jdkoverview.OuterClass.InnerClass binary Name:

Org.javaplus.jdkoverview.outerclass$innerclassjava.lang.compiler This class provides Java to native code support, and related services. This class is just a placeholder for the JIT compiler (Java Just-in-Time Compiler). This class does nothing if the JVM (Java Virtual Machine) does not successfully load the JIT compiler the first time it starts. Java.lang.Double a class that objects the original data type double. The instance object of the class, in addition to including a double value, provides a way to handle double, such as converting between a double and other types.