Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels) Summary: [Ctors](https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#pubctors) \| [Methods](https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#pubmethods) \| [Inherited Methods](https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#inhmethods)

# DoubleAdder

` public class DoubleAdder `   
` ` ` extends https://developer.android.com/reference/java/lang/Number ` ` implements https://developer.android.com/reference/java/io/Serializable `

|---|---|---|
| [java.lang.Object](https://developer.android.com/reference/java/lang/Object) |||
| ↳ | [java.lang.Number](https://developer.android.com/reference/java/lang/Number) ||
|   | ↳ | java.util.concurrent.atomic.DoubleAdder |

<br />

*** ** * ** ***

One or more variables that together maintain an initially zero `double` sum. When updates (method `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#add(double)`) are contended across threads, the set of variables may grow dynamically to reduce contention. Method `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()` (or, equivalently `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#doubleValue()`) returns the current total combined across the variables maintaining the sum. The order of accumulation within or across threads is not guaranteed. Thus, this class may not be applicable if numerical stability is required, especially when combining values of substantially different orders of magnitude.

This class is usually preferable to alternatives when multiple threads update a common value that is used for purposes such as summary statistics that are frequently updated but less frequently read.

This class extends `https://developer.android.com/reference/java/lang/Number`, but does *not* define methods such as `equals`, `hashCode` and `compareTo` because instances are expected to be mutated, and so are not useful as collection keys.

## Summary

| ### Public constructors ||
|---|---|
| ` https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#DoubleAdder()() ` Creates a new adder with initial sum of zero. |

| ### Public methods ||
|---|---|
| ` void` | ` https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#add(double)(double x) ` Adds the given value. |
| ` double` | ` https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#doubleValue()() ` Equivalent to `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()`. |
| ` float` | ` https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#floatValue()() ` Returns the `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()` as a `float` after a narrowing primitive conversion. |
| ` int` | ` https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#intValue()() ` Returns the `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()` as an `int` after a narrowing primitive conversion. |
| ` long` | ` https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#longValue()() ` Returns the `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()` as a `long` after a narrowing primitive conversion. |
| ` void` | ` https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#reset()() ` Resets variables maintaining the sum to zero. |
| ` double` | ` https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()() ` Returns the current sum. |
| ` double` | ` https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sumThenReset()() ` Equivalent in effect to `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()` followed by `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#reset()`. |
| ` https://developer.android.com/reference/java/lang/String` | ` https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#toString()() ` Returns the String representation of the `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()`. |

### Inherited methods

From class ` https://developer.android.com/reference/java/lang/Number ` ` byte` ` https://developer.android.com/reference/java/lang/Number#byteValue()() `

Returns the value of the specified number as a `byte`.
` abstract double` ` https://developer.android.com/reference/java/lang/Number#doubleValue()() `

Returns the value of the specified number as a `double`.
` abstract float` ` https://developer.android.com/reference/java/lang/Number#floatValue()() `

Returns the value of the specified number as a `float`.
` abstract int` ` https://developer.android.com/reference/java/lang/Number#intValue()() `

Returns the value of the specified number as an `int`.
` abstract long` ` https://developer.android.com/reference/java/lang/Number#longValue()() `

Returns the value of the specified number as a `long`.
` short` ` https://developer.android.com/reference/java/lang/Number#shortValue()() `

Returns the value of the specified number as a `short`.
From class ` https://developer.android.com/reference/java/lang/Object ` ` https://developer.android.com/reference/java/lang/Object` ` https://developer.android.com/reference/java/lang/Object#clone()() `

Creates and returns a copy of this object.
` boolean` ` https://developer.android.com/reference/java/lang/Object#equals(java.lang.Object)(https://developer.android.com/reference/java/lang/Object obj) `

Indicates whether some other object is "equal to" this one.
` void` ` https://developer.android.com/reference/java/lang/Object#finalize()() `

Called by the garbage collector on an object when garbage collection determines that there are no more references to the object.
` final https://developer.android.com/reference/java/lang/Class<?>` ` https://developer.android.com/reference/java/lang/Object#getClass()() `

Returns the runtime class of this `Object`.
` int` ` https://developer.android.com/reference/java/lang/Object#hashCode()() `

Returns a hash code value for the object.
` final void` ` https://developer.android.com/reference/java/lang/Object#notify()() `

Wakes up a single thread that is waiting on this object's monitor.
` final void` ` https://developer.android.com/reference/java/lang/Object#notifyAll()() `

Wakes up all threads that are waiting on this object's monitor.
` https://developer.android.com/reference/java/lang/String` ` https://developer.android.com/reference/java/lang/Object#toString()() `

Returns a string representation of the object.
` final void` ` https://developer.android.com/reference/java/lang/Object#wait(long,%20int)(long timeoutMillis, int nanos) `

Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*, or until a certain amount of real time has elapsed.
` final void` ` https://developer.android.com/reference/java/lang/Object#wait(long)(long timeoutMillis) `

Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*, or until a certain amount of real time has elapsed.
` final void` ` https://developer.android.com/reference/java/lang/Object#wait()() `

Causes the current thread to wait until it is awakened, typically by being *notified* or *interrupted*.

## Public constructors

### DoubleAdder

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public DoubleAdder ()
```

Creates a new adder with initial sum of zero.

<br />

## Public methods

### add

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public void add (double x)
```

Adds the given value.

<br />

| Parameters ||
|---|---|
| `x` | `double`: the value to add <br /> |

### doubleValue

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public double doubleValue ()
```

Equivalent to `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()`.

<br />

| Returns ||
|---|---|
| `double` | the sum <br /> |

### floatValue

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public float floatValue ()
```

Returns the `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()` as a `float` after a narrowing primitive conversion.

<br />

| Returns ||
|---|---|
| `float` | the numeric value represented by this object after conversion to type `float`. <br /> |

### intValue

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public int intValue ()
```

Returns the `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()` as an `int` after a narrowing primitive conversion.

<br />

| Returns ||
|---|---|
| `int` | the numeric value represented by this object after conversion to type `int`. <br /> |

### longValue

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public long longValue ()
```

Returns the `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()` as a `long` after a narrowing primitive conversion.

<br />

| Returns ||
|---|---|
| `long` | the numeric value represented by this object after conversion to type `long`. <br /> |

### reset

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public void reset ()
```

Resets variables maintaining the sum to zero. This method may be a useful alternative to creating a new adder, but is only effective if there are no concurrent updates. Because this method is intrinsically racy, it should only be used when it is known that no threads are concurrently updating.

<br />

### sum

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public double sum ()
```

Returns the current sum. The returned value is *NOT* an atomic snapshot; invocation in the absence of concurrent updates returns an accurate result, but concurrent updates that occur while the sum is being calculated might not be incorporated. Also, because floating-point arithmetic is not strictly associative, the returned result need not be identical to the value that would be obtained in a sequential series of updates to a single variable.

<br />

| Returns ||
|---|---|
| `double` | the sum <br /> |

### sumThenReset

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public double sumThenReset ()
```

Equivalent in effect to `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()` followed by `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#reset()`. This method may apply for example during quiescent points between multithreaded computations. If there are updates concurrent with this method, the returned value is *not* guaranteed to be the final value occurring before the reset.

<br />

| Returns ||
|---|---|
| `double` | the sum <br /> |

### toString

Added in [API level 24](https://developer.android.com/guide/topics/manifest/uses-sdk-element#ApiLevels)

```
public String toString ()
```

Returns the String representation of the `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()`.

<br />

| Returns ||
|---|---|
| `https://developer.android.com/reference/java/lang/String` | the String representation of the `https://developer.android.com/reference/java/util/concurrent/atomic/DoubleAdder#sum()` <br /> |