【正文】 y has inserted the nearly all operating Java procedure may only translate one time, may move in each kind of Java application programming interface already developed from the version to present the monly used Java platform based on , the recent edition is . Java divides into three system JavaSE, JavaEE, JavaME. 二 Java language The Java language is a support work putation objectoriented programming Java language has absorbed the Smalltalk language and the C language merit, and increased other characteristics, like support concurrent programming, work correspondence, and multimedia data management and so principal characteristic is as follows: 1st, the Java language is Java language grammar and the C language and the C language are very close, make the majority programmers to be very easy to study and to use the other hand, Java has discarded C Very little uses, very difficultly to understand, the misleading these characteristics, like instruction character heavy load, multiinheritances, automatic pulsion type transformation. The Java language does not use the indicator specially, and has provided the automatic waste material collection, causes the programmer not to need to worry for the memory management. 2nd, the Java language is one Java language provides kind of, primitive and so on connection and inheritance, for simplicity, only supports class the between list inheritance, but between the support connection multiinheritances, and support class and between the connection realization mechanism (key words are implements).Java language prehensive support dynamic binding, but C Language only to empty function use dynamic binding. In brief, the Java language is a pure objectoriented programming language. 3rd, the Java language is Java language supports the Inter application the development, has a work application programming interface in the basic Java application programming interface (), it provided has used in the work application programming a kind of storehouse, including URL, URLConnection, Socket, ServerSocket and so on. 13 Java RMI (longdistance method activates) the mechanism also is develops the distributional application the important method. 4th, the Java language is vigorous and Java strong type machinemade, the exception handling, the waste material automatic collection and so on is the Java procedure toughness important indicator discarding is the Java unwise Java security check mechanism causes Java to have the toughness. 5th, the Java language is is usually used in the work environment, for this, Java provided a safety mechanism to guard against the malicious code the attack. Many security features has which besides the Java language, Java to has a safe guard mechanism through the work downloading kind (kind of ClassLoader), like the assignment different name space guards against the substitution locally of the same name kind of, the syllabified code inspection, and provides the safety control mechanism (kind of SecurityManager) to let Java apply the establishment security sentry. 6th, the Java language is the architecture Java procedure (suffix is the java document) is translated in the Java platform for the architecture neutrality byte code form (suffix is the class document), then may in realize in this Java platform any system to way suits in isomerism work environment and the software distribution. 7th, the Java language is may kind of probability originates from the architecture neutrality, moreover, Java strictly has also stipulated each master data type system itself also has the very strong probability, the Java piler is realizes with Java, the Java movement environment is realizes with ANSI C. 8th, the Java language is the mentioned above, the Java procedure is translated in the Java platform for the byte code form, then may in realize in this Java platform any system to movement, Java in the platform Java interpreter carries on the explanation execution to these bytes codes, the kind which in the implementation needs is written down in the joint stage in the movement environment. 9th, Java is a high with these explanation highlevel script language, Java indeed is a high fact, the Java running rate more and more approaches along with the JIT(JustInTime) piler technology development in C. 10th, the Java language is a the Java language, the thread is one kind of special object, it must or its sub(grandson) the kind founds by the Thread kind. Usually has two methods to found the thread: First, the operational construction was the Thread(Runnable) structure realizes one the Runnable connection object packing to bee a thread, its two, derived the subclass from the Thread kind and rewrites the run method, uses the object which this subclass founded is the thread. It is noteworthy that the Thread kind has already realized the Runnable connection, therefore, any thread had its run method, but in the run method has contained the code which the thread had to thread activity controls by group of methods. The Java language supports many threads at the same time execution, and provides between multithread the synchronized mechanism (key words is synchronized). 11th, the Java language is of Java language design goals is adapts in the dynamic change Java procedure needs the kind can dynamic write down the movement environment, also may write down the kind through the work which is also advantageous to the software , in the Java kind has a movement time expression, can carry on the movement time the type inspection. The Java language f