Most visited

Recently visited

Added in API level 1

Signature

public class Signature
extends Object implements Parcelable

java.lang.Object
   ↳ android.content.pm.Signature


与应用程序包关联的签名证书的不透明,不可变表示。

这个类名称有些误导,因为它实际上不是签名。

Summary

Inherited constants

From interface android.os.Parcelable

Fields

public static final Creator<Signature> CREATOR

Public constructors

Signature(byte[] signature)

从现有的原始字节数组创建签名。

Signature(String text)

通过以前由 toChars()toCharsString()返回的文本表示创建签名。

Public methods

int describeContents()

描述此Parcelable实例的封送表示中包含的特殊对象的种类。

boolean equals(Object obj)

指示其他某个对象是否“等于”这一个。

int hashCode()

返回对象的哈希码值。

byte[] toByteArray()
char[] toChars()

将签名编码为ASCII文本。

char[] toChars(char[] existingArray, int[] outLen)

将签名编码为ASCII文本到现有数组中。

String toCharsString()

以字符串形式返回 toChars()的结果。

void writeToParcel(Parcel dest, int parcelableFlags)

将此对象平铺到一个包裹中。

Inherited methods

From class java.lang.Object
From interface android.os.Parcelable

Fields

CREATOR

Added in API level 1
Creator<Signature> CREATOR

Public constructors

Signature

Added in API level 1
Signature (byte[] signature)

从现有的原始字节数组创建签名。

Parameters
signature byte

Signature

Added in API level 1
Signature (String text)

从之前由toChars()toCharsString()返回的文本表示创建签名。 预计签名是一个十六进制编码的ASCII字符串。

Parameters
text String: hex-encoded string representing the signature
Throws
IllegalArgumentException when signature is odd-length

Public methods

describeContents

Added in API level 1
int describeContents ()

描述此Parcelable实例的封送表示中包含的特殊对象的种类。 例如,如果对象将在writeToParcel(Parcel, int)的输出中包含writeToParcel(Parcel, int) ,则此方法的返回值必须包含CONTENTS_FILE_DESCRIPTOR位。

Returns
int a bitmask indicating the set of special object types marshaled by this Parcelable object instance.

equals

Added in API level 1
boolean equals (Object obj)

指示其他某个对象是否“等于”这一个。

equals方法在非空对象引用上实现等价关系:

  • It is reflexive: for any non-null reference value x, x.equals(x) should return true.
  • It is symmetric: for any non-null reference values x and y, x.equals(y) should return true if and only if y.equals(x) returns true.
  • It is transitive: for any non-null reference values x, y, and z, if x.equals(y) returns true and y.equals(z) returns true, then x.equals(z) should return true.
  • It is consistent: for any non-null reference values x and y, multiple invocations of x.equals(y) consistently return true or consistently return false, provided no information used in equals comparisons on the objects is modified.
  • For any non-null reference value x, x.equals(null) should return false.

Objectequals方法实现了对象上最可能的等价关系; 也就是说,对于任何非空参考值xy ,当且仅当xy指向同一对象( x == y的值为true )时,此方法返回true

请注意,无论何时覆盖此方法,通常都需要覆盖 hashCode方法,以维护 hashCode方法的一般合同,该方法声明相等对象必须具有相同的散列代码。

Parameters
obj Object: the reference object with which to compare.
Returns
boolean true if this object is the same as the obj argument; false otherwise.

hashCode

Added in API level 1
int hashCode ()

返回对象的哈希码值。 为了散列表的好处而支持此方法,例如由HashMap提供的HashMap

hashCode的总合同是:

  • Whenever it is invoked on the same object more than once during an execution of a Java application, the hashCode method must consistently return the same integer, provided no information used in equals comparisons on the object is modified. This integer need not remain consistent from one execution of an application to another execution of the same application.
  • If two objects are equal according to the equals(Object) method, then calling the hashCode method on each of the two objects must produce the same integer result.
  • It is not required that if two objects are unequal according to the equals(java.lang.Object) method, then calling the hashCode method on each of the two objects must produce distinct integer results. However, the programmer should be aware that producing distinct integer results for unequal objects may improve the performance of hash tables.

尽可能合理实用,由类Object定义的hashCode方法确实为不同的对象返回不同的整数。 (这通常通过将对象的内部地址转换为整数来实现,但Java TM编程语言不需要此实现技术。)

Returns
int a hash code value for this object.

toByteArray

Added in API level 1
byte[] toByteArray ()

Returns
byte[] the contents of this signature as a byte array.

toChars

Added in API level 1
char[] toChars ()

将签名编码为ASCII文本。

Returns
char[]

toChars

Added in API level 1
char[] toChars (char[] existingArray, 
                int[] outLen)

将签名编码为ASCII文本到现有数组中。

Parameters
existingArray char: Existing char array or null.
outLen int: Output parameter for the number of characters written in to the array.
Returns
char[] Returns either existingArray if it was large enough to hold the ASCII representation, or a newly created char[] array if needed.

toCharsString

Added in API level 1
String toCharsString ()

以字符串形式返回 toChars()的结果。

Returns
String

writeToParcel

Added in API level 1
void writeToParcel (Parcel dest, 
                int parcelableFlags)

将此对象平铺到一个包裹中。

Parameters
dest Parcel: The Parcel in which the object should be written.
parcelableFlags int: Additional flags about how the object should be written. May be 0 or PARCELABLE_WRITE_RETURN_VALUE.

Hooray!