將一個字節分成幾部分

Question

我有一個字節00111101.我想將它分成兩部分，如0011 1101，並創建兩個新字節00000011和00001101.我怎樣才能在Java中完成它？

我的代碼是：

byte b; //b has a particular value 
byte result1= (b>>4) && 0x0f; 
byte result2= b & 0x0f; 

此代碼是給我下面的錯誤：

cannot convert from int to byte. 

Answer 1

你只需要添加一個投：

byte result1= (byte) ((b>>4) && 0x0f); 
byte result2= (byte) (b & 0x0f); 

運算的結果對小於int的整數類型的操作隱式提升爲int，所以你必須把它扔回byte。

JLS 5.6.2指定此行爲的二進制數值提升規則的一部分：

Widening primitive conversion (§5.1.2) is applied to convert either or both operands as specified by the following rules:

If either operand is of type double, the other is converted to double.

Otherwise, if either operand is of type float, the other is converted to float.

Otherwise, if either operand is of type long, the other is converted to long.

Otherwise, both operands are converted to type int.