CloseGuard Class
Definition
Important
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CloseGuard is a mechanism for flagging implicit finalizer cleanup of resources that should have been cleaned up by explicit close methods (aka "explicit termination methods" in Effective Java).
[Android.Runtime.Register("android/util/CloseGuard", ApiSince=30, DoNotGenerateAcw=true)]
public sealed class CloseGuard : Java.Lang.Object[<Android.Runtime.Register("android/util/CloseGuard", ApiSince=30, DoNotGenerateAcw=true)>]
type CloseGuard = class
inherit Object- Inheritance
- Attributes
Remarks
CloseGuard is a mechanism for flagging implicit finalizer cleanup of resources that should have been cleaned up by explicit close methods (aka "explicit termination methods" in Effective Java).
A simple example:
{@code
class Foo {
private final CloseGuard guard = new CloseGuard();
...
public Foo() {
...;
guard.open("cleanup");
}
public void cleanup() {
guard.close();
...;
if (Build.VERSION.SDK_INT >= 28) {
Reference.reachabilityFence(this);
}
// For full correctness in the absence of a close() call, other methods may also need
// reachabilityFence() calls.
}
protected void finalize() throws Throwable {
try {
// Note that guard could be null if the constructor threw.
if (guard != null) {
guard.warnIfOpen();
}
cleanup();
} finally {
super.finalize();
}
}
}
}
In usage where the resource to be explicitly cleaned up is allocated after object construction, CloseGuard protection can be deferred. For example:
{@code
class Bar {
private final CloseGuard guard = new CloseGuard();
...
public Bar() {
...;
}
public void connect() {
...;
guard.open("cleanup");
}
public void cleanup() {
guard.close();
...;
if (Build.VERSION.SDK_INT >= 28) {
Reference.reachabilityFence(this);
}
// For full correctness in the absence of a close() call, other methods may also need
// reachabilityFence() calls.
}
protected void finalize() throws Throwable {
try {
// Note that guard could be null if the constructor threw.
if (guard != null) {
guard.warnIfOpen();
}
cleanup();
} finally {
super.finalize();
}
}
}
}
When used in a constructor, calls to open should occur at the end of the constructor since an exception that would cause abrupt termination of the constructor will mean that the user will not have a reference to the object to cleanup explicitly. When used in a method, the call to open should occur just after resource acquisition.
Java documentation for android.util.CloseGuard.
Portions of this page are modifications based on work created and shared by the Android Open Source Project and used according to terms described in the Creative Commons 2.5 Attribution License.
Constructors
| CloseGuard() |
Constructs a new CloseGuard instance. |
Properties
| Class |
Returns the runtime class of this |
| Handle |
The handle to the underlying Android instance. (Inherited from Object) |
| JniIdentityHashCode | (Inherited from Object) |
| JniPeerMembers | |
| PeerReference | (Inherited from Object) |
| ThresholdClass |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. (Inherited from Object) |
| ThresholdType |
This API supports the Mono for Android infrastructure and is not intended to be used directly from your code. (Inherited from Object) |
Methods
| Clone() |
Creates and returns a copy of this object. (Inherited from Object) |
| Close() |
Marks this CloseGuard instance as closed to avoid warnings on finalization. |
| Dispose() | (Inherited from Object) |
| Dispose(Boolean) | (Inherited from Object) |
| Equals(Object) |
Indicates whether some other object is "equal to" this one. (Inherited from Object) |
| GetHashCode() |
Returns a hash code value for the object. (Inherited from Object) |
| JavaFinalize() |
Called by the garbage collector on an object when garbage collection determines that there are no more references to the object. (Inherited from Object) |
| Notify() |
Wakes up a single thread that is waiting on this object's monitor. (Inherited from Object) |
| NotifyAll() |
Wakes up all threads that are waiting on this object's monitor. (Inherited from Object) |
| Open(String) |
Initializes the instance with a warning that the caller should have explicitly called the
|
| SetHandle(IntPtr, JniHandleOwnership) |
Sets the Handle property. (Inherited from Object) |
| ToArray<T>() | (Inherited from Object) |
| ToString() |
Returns a string representation of the object. (Inherited from Object) |
| UnregisterFromRuntime() | (Inherited from Object) |
| Wait() |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>. (Inherited from Object) |
| Wait(Int64, Int32) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
| Wait(Int64) |
Causes the current thread to wait until it is awakened, typically by being <em>notified</em> or <em>interrupted</em>, or until a certain amount of real time has elapsed. (Inherited from Object) |
| WarnIfOpen() |
Logs a warning if the caller did not properly cleanup by calling an explicit close method before finalization. |
Explicit Interface Implementations
| IJavaPeerable.Disposed() | (Inherited from Object) |
| IJavaPeerable.DisposeUnlessReferenced() | (Inherited from Object) |
| IJavaPeerable.Finalized() | (Inherited from Object) |
| IJavaPeerable.JniManagedPeerState | (Inherited from Object) |
| IJavaPeerable.SetJniIdentityHashCode(Int32) | (Inherited from Object) |
| IJavaPeerable.SetJniManagedPeerState(JniManagedPeerStates) | (Inherited from Object) |
| IJavaPeerable.SetPeerReference(JniObjectReference) | (Inherited from Object) |
Extension Methods
| JavaCast<TResult>(IJavaObject) |
Performs an Android runtime-checked type conversion. |
| JavaCast<TResult>(IJavaObject) | |
| GetJniTypeName(IJavaPeerable) | |