Java的操作符

运算符可以是一元、二元或三元的。
（1）一元运算符有1个操作数。例如，递增运算符"++"就是一元运算符。

 /** Unary operators, of type Unary.
     */
    public static final int POS = ERRONEOUS + 1;             // +
    public static final int NEG = POS + 1;                   // -
    public static final int NOT = NEG + 1;                   // !
    public static final int COMPL = NOT + 1;                 // ~
    public static final int PREINC = COMPL + 1;              // ++ _
    public static final int PREDEC = PREINC + 1;             // -- _
    public static final int POSTINC = PREDEC + 1;            // _ ++
    public static final int POSTDEC = POSTINC + 1;           // _ --

    /** unary operator for null reference checks, only used internally.
     */
    public static final int NULLCHK = POSTDEC + 1;

（2）二元运算符有2个操作数。例如，除法运算符"/"有2个操作数。

  /** Binary operators, of type Binary.
     */
    public static final int OR = NULLCHK + 1;                // ||
    public static final int AND = OR + 1;                    // &&
    public static final int BITOR = AND + 1;                 // |
    public static final int BITXOR = BITOR + 1;              // ^
    public static final int BITAND = BITXOR + 1;             // &
    public static final int EQ = BITAND + 1;                 // ==
    public static final int NE = EQ + 1;                     // !=
    public static final int LT = NE + 1;                     // <
    public static final int GT = LT + 1;                     // >
    public static final int LE = GT + 1;                     // <=
    public static final int GE = LE + 1;                     // >=
    public static final int SL = GE + 1;                     // <<
    public static final int SR = SL + 1;                     // >>
    public static final int USR = SR + 1;                    // >>>
    public static final int PLUS = USR + 1;                  // +
    public static final int MINUS = PLUS + 1;                // -
    public static final int MUL = MINUS + 1;                 // *
    public static final int DIV = MUL + 1;                   // /
    public static final int MOD = DIV + 1;                   // %

    /** Assignment operators, of type Assignop.
     */
    public static final int BITOR_ASG = MOD + 1;             // |=
    public static final int BITXOR_ASG = BITOR_ASG + 1;      // ^=
    public static final int BITAND_ASG = BITXOR_ASG + 1;     // &=

    public static final int SL_ASG = SL + BITOR_ASG - BITOR; // <<=
    public static final int SR_ASG = SL_ASG + 1;             // >>=
    public static final int USR_ASG = SR_ASG + 1;            // >>>=
    public static final int PLUS_ASG = USR_ASG + 1;          // +=
    public static final int MINUS_ASG = PLUS_ASG + 1;        // -=
    public static final int MUL_ASG = MINUS_ASG + 1;         // *=
    public static final int DIV_ASG = MUL_ASG + 1;           // /=
    public static final int MOD_ASG = DIV_ASG + 1;           // %=

（3）三元运算符有3个操作数。例如，条件运算符"?:"具有3个操作数。

运算符的行为还可能因所提供的操作数的数量而异。减法运算符"-"既是一元运算符又是二元运算符。对于减法运算符，如果只提供一个操作数，
则该运算符会对操作数取反并返回结果；如果提供两个操作数，则减法运算符返回这两个操作数的差。

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