MathContext

java.lang.Object
- java.math.MathContext

所有已实现的接口:

Serializable
```
public final class MathContext
extends Object
implements Serializable
```
Immutable objects which encapsulate the context settings which describe certain rules for numerical operators, such as those implemented by the BigDecimal class.
The base-independent settings are:
1. precision: the number of digits to be used for an operation; results are rounded to this precision
2. roundingMode: a RoundingMode object which specifies the algorithm to be used for rounding.
从以下版本开始:

1.5

另请参阅:

BigDecimal, RoundingMode, 序列化表格

字段概要

字段
限定符和类型	字段	说明
`static MathContext`	`DECIMAL128`	A `MathContext` object with a precision setting matching the IEEE 754R Decimal128 format, 34 digits, and a rounding mode of `RoundingMode#HALF_EVEN`, the IEEE 754R default.
`static MathContext`	`DECIMAL32`	A `MathContext` object with a precision setting matching the IEEE 754R Decimal32 format, 7 digits, and a rounding mode of `RoundingMode#HALF_EVEN`, the IEEE 754R default.
`static MathContext`	`DECIMAL64`	A `MathContext` object with a precision setting matching the IEEE 754R Decimal64 format, 16 digits, and a rounding mode of `RoundingMode#HALF_EVEN`, the IEEE 754R default.
`static MathContext`	`UNLIMITED`	A `MathContext` object whose settings have the values required for unlimited precision arithmetic.

构造器概要

构造器
构造器	说明
`MathContext(int setPrecision)`	Constructs a new `MathContext` with the specified precision and the `RoundingMode#HALF_UP` rounding mode.
`MathContext(int setPrecision, RoundingMode setRoundingMode)`	Constructs a new `MathContext` with a specified precision and rounding mode.
`MathContext(String val)`	Constructs a new `MathContext` from a string.

方法概要

所有方法实例方法具体方法
限定符和类型	方法	说明
`boolean`	`equals(Object x)`	Compares this `MathContext` with the specified `Object` for equality.
`int`	`getPrecision()`	Returns the `precision` setting.
`RoundingMode`	`getRoundingMode()`	Returns the roundingMode setting.
`int`	`hashCode()`	Returns the hash code for this `MathContext`.
`String`	`toString()`	Returns the string representation of this `MathContext`.

从类继承的方法 java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait

- 字段详细资料
  - DECIMAL128
```
public static final MathContext DECIMAL128
```
    A MathContext object with a precision setting matching the IEEE 754R Decimal128 format, 34 digits, and a rounding mode of RoundingMode#HALF_EVEN, the IEEE 754R default.
  - DECIMAL32
```
public static final MathContext DECIMAL32
```
    A MathContext object with a precision setting matching the IEEE 754R Decimal32 format, 7 digits, and a rounding mode of RoundingMode#HALF_EVEN, the IEEE 754R default.
  - DECIMAL64
```
public static final MathContext DECIMAL64
```
    A MathContext object with a precision setting matching the IEEE 754R Decimal64 format, 16 digits, and a rounding mode of RoundingMode#HALF_EVEN, the IEEE 754R default.
  - UNLIMITED
```
public static final MathContext UNLIMITED
```
    A MathContext object whose settings have the values required for unlimited precision arithmetic. The values of the settings are: precision=0 roundingMode=HALF_UP
- 构造器详细资料
  - MathContext
```
public MathContext(int setPrecision)
```
    Constructs a new MathContext with the specified precision and the RoundingMode#HALF_UP rounding mode.
    
    参数:
    
    setPrecision - The non-negative int precision setting.
    
    抛出:
    
    IllegalArgumentException - if the setPrecision parameter is less than zero.
  - MathContext
```
public MathContext(int setPrecision,
                   RoundingMode setRoundingMode)
```
    Constructs a new MathContext with a specified precision and rounding mode.
    
    参数:
    
    setPrecision - The non-negative int precision setting.
    
    setRoundingMode - The rounding mode to use.
    
    抛出:
    
    IllegalArgumentException - if the setPrecision parameter is less than zero.
    
    NullPointerException - if the rounding mode argument is null
  - MathContext
```
public MathContext(String val)
```
    Constructs a new MathContext from a string. The string must be in the same format as that produced by the toString() method.
    An IllegalArgumentException is thrown if the precision section of the string is out of range (< 0) or the string is not in the format created by the toString() method.
    
    参数:
    
    val - The string to be parsed
    
    抛出:
    
    IllegalArgumentException - if the precision section is out of range or of incorrect format
    
    NullPointerException - if the argument is null
- 方法详细资料
  - getPrecision
```
public int getPrecision()
```
    Returns the precision setting. This value is always non-negative.
    
    返回:
    
    an int which is the value of the precision setting
  - getRoundingMode
```
public RoundingMode getRoundingMode()
```
    Returns the roundingMode setting. This will be one of RoundingMode#CEILING, RoundingMode#DOWN, RoundingMode#FLOOR, RoundingMode#HALF_DOWN, RoundingMode#HALF_EVEN, RoundingMode#HALF_UP, RoundingMode#UNNECESSARY, or RoundingMode#UP.
    
    返回:
    
    a RoundingMode object which is the value of the roundingMode setting
  - equals
```
public boolean equals(Object x)
```
    Compares this MathContext with the specified Object for equality.
    
    覆盖:
    
    equals 在类中 Object
    
    参数:
    
    x - Object to which this MathContext is to be compared.
    
    返回:
    
    true if and only if the specified Object is a MathContext object which has exactly the same settings as this object
    
    另请参阅:
    
    Object.hashCode(), HashMap
  - hashCode
```
public int hashCode()
```
    Returns the hash code for this MathContext.
    
    覆盖:
    
    hashCode 在类中 Object
    
    返回:
    
    hash code for this MathContext
    
    另请参阅:
    
    Object.equals(java.lang.Object), System.identityHashCode(java.lang.Object)
  - toString
```
public String toString()
```
    Returns the string representation of this MathContext. The String returned represents the settings of the MathContext object as two space-delimited words (separated by a single space character, '\u0020', and with no leading or trailing white space), as follows:
    1. The string "precision=", immediately followed by the value of the precision setting as a numeric string as if generated by the Integer#toString(int) method.
    2. The string "roundingMode=", immediately followed by the value of the roundingMode setting as a word. This word will be the same as the name of the corresponding public constant in the RoundingMode enum.
    For example:
```
 precision=9 roundingMode=HALF_UP
 
```
    Additional words may be appended to the result of toString in the future if more properties are added to this class.
    覆盖:
    
    toString 在类中 Object
    
    返回:
    
    a String representing the context settings

类 MathContext

字段概要

构造器概要

方法概要

从类继承的方法 java.lang.Object

字段详细资料

DECIMAL128

DECIMAL32

DECIMAL64

UNLIMITED

构造器详细资料

MathContext

MathContext

MathContext

方法详细资料

getPrecision

getRoundingMode

equals

hashCode

toString