1、java language does not use a local varible that has not been initialized.
java語(yǔ)言中，尚未初始化的局部變量不可以被使用(也就是說(shuō)，在使用一個(gè)局部變量之前，必須先初始化它)。
2、There are some differences between class methods and instance methods.
類(lèi)方法和實(shí)例方法之間是有區別的。
3、A class is a data type;a class value is called an Object.
“類(lèi)”是一種數據類(lèi)型；一個(gè)類(lèi)的值稱(chēng)為對象。
4、Java only allows an object to be cloned if the object‘s class has explicitly declared itself to be cloneable by implementing the Cloneable interface.
Java中，只有當某個(gè)類(lèi)通過(guò)實(shí)現Cloneable 接口顯式的聲明它自己是可克隆的，這個(gè)類(lèi)的所屬的對象才能被克隆。
5、"=="just test whether two references refer to the same object;it does not test whether two object have the same content.
“＝＝”只是判斷兩個(gè)“引用”引用的是否是同一個(gè)對象；它并沒(méi)有判斷兩個(gè)對象的內容是否相同。
6、java is a "pass by value" language.However, when a reference type is involved ,the value that is passed is a reference.But this is not the same as pass-by-reference.
java語(yǔ)言是“值傳遞”的。只不過(guò)在涉及“引用”類(lèi)型時(shí)，被傳遞的值是一個(gè)“引用”罷了。這與“引用傳遞”有所不同。
7、An array of primitve type cannot converted to any other array type,even if the primitive base types can be converted.
原語(yǔ)類(lèi)型數據的數組不能轉化為其他的數組類(lèi)型，盡管這種原數據可以被轉化。(比如，int型雖然可以轉換為float型，但int[]型不能轉化為float[]型。)
8、Java 5.0 introduces two new types of conversions known as boxing and unboxing conversions. Boxing conversions convert a primitive value to its corresponding wrapper object and unboxing conversions do the opposite.
java5引入了boxing 和unboxing 兩種新的轉化類(lèi)型；boxing 可以將原語(yǔ)類(lèi)型數據裝化為它相應的類(lèi)包裝器對象，unboxing 則是反過(guò)來(lái)。
9、In Java 5.0 and later, you can import the static members of types as well as types themselves using the keywords ‘import static‘.
java 5.0以后的版本，通過(guò)“import”你不僅可以導入類(lèi)，還可以導入這些類(lèi)的靜態(tài)成員，只需要使用‘import static‘關(guān)鍵字。
10、Each method that operates on a string typically returns a new String object that holds the modified string.
任何一種在字符串上操作的方法，返回的都是一個(gè)新的、包含修改過(guò)的字符串的String對象。
11、In java2 new io ,what implements nonblocking io is Selector!!!
在java2 新的io包(java.nio.*)中，真正實(shí)現了非阻塞的是Selector!!!
12、The New I/O API allows most channels (but not FileChannel) to be used in nonblocking mode and allows a single thread to manage all pending connections. This is done with a Selector object, which keeps track of a set of registered channels and can block until one or more of those channels is ready for I/O.
新的I/O API (java.nio.*)允許大部分的通道類(lèi)(不包括FileChannel類(lèi))用于非阻塞模式，并且允許一個(gè)單獨的線(xiàn)程來(lái)管理等待的連接。這是通過(guò)一個(gè)Selector 對象來(lái)實(shí)現的，它負責追蹤已注冊的通道對象，直到一個(gè)或多個(gè)通道已經(jīng)準備好輸入/輸出才阻塞。
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