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## com.trolltech.qt.network
Class QHostInfo

    java.lang.Object
      com.trolltech.qt.internal.QSignalEmitterInternal
          com.trolltech.qt.QSignalEmitter
              com.trolltech.qt.QtJambiObject
                  com.trolltech.qt.network.QHostInfo

All Implemented Interfaces:
  QtJambiInterface, java.lang.Cloneable

    public class QHostInfo

extends QtJambiObject
implements java.lang.Cloneable

The QHostInfo class provides static functions for host name lookups. QHostInfo uses the lookup mechanisms provided by the operating system to find the IP address(es) associated with a host name, or the host name associated with an IP address. The class provides two static convenience functions: one that works asynchronously and emits a signal once the host is found, and one that blocks and returns a QHostInfo object.

To look up a host's IP addresses asynchronously, call `lookupHost()`, which takes the host name or IP address, a receiver object, and a slot signature as arguments and returns an ID. You can abort the lookup by calling `abortHostLookup()` with the lookup ID.

Example:

            // To find the IP address of www.trolltech.com
            QHostInfo.lookupHost("www.trolltech.com",
                     this, "printResults(QHostInfo)");

            // To find the host name for 4.2.2.1
            QHostInfo.lookupHost("4.2.2.1",
                     this, "printResults(QHostInfo)");

The slot is invoked when the results are ready. (If you use Qt for Embedded Linux and disabled multithreading support by defining `QT_NO_THREAD`, `lookupHost()` will block until the lookup has finished.) The results are stored in a QHostInfo object. Call `addresses()` to get the list of IP addresses for the host, and `hostName()` to get the host name that was looked up.

If the lookup failed, `error()` returns the type of error that occurred. `errorString()` gives a human-readable description of the lookup error.

If you want a blocking lookup, use the `QHostInfo::fromName()` function:

            QHostInfo info = QHostInfo.fromName("www.trolltech.com");

QHostInfo supports Internationalized Domain Names (IDNs) through the IDNA and Punycode standards.

To retrieve the name of the local host, use the static `QHostInfo::localHostName()` function.

See also:
  `QAbstractSocket`, and

Nested Class Summary
`static class` | `QHostInfo.HostInfoError` This enum describes the various errors that can occur when trying to resolve a host name.

Nested classes/interfaces inherited from class com.trolltech.qt.QSignalEmitter
`QSignalEmitter.AbstractSignal, QSignalEmitter.Signal0, QSignalEmitter.Signal1, QSignalEmitter.Signal2, QSignalEmitter.Signal3, QSignalEmitter.Signal4, QSignalEmitter.Signal5, QSignalEmitter.Signal6, QSignalEmitter.Signal7, QSignalEmitter.Signal8, QSignalEmitter.Signal9`

Nested classes/interfaces inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`com.trolltech.qt.internal.QSignalEmitterInternal.AbstractSignalInternal`

Field Summary

Fields inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`currentSender`

Constructor Summary
`QHostInfo()` Constructs an empty host info object with lookup ID `id`.
`QHostInfo(int lookupId)` Constructs an empty host info object with lookup ID `id`.
`QHostInfo(QHostInfo d)` Constructs a copy of `other`.

Method Summary
`static void` | `abortHostLookup(int lookupId)` Aborts the host lookup with the ID `id`, as returned by `lookupHost()`.
`java.util.List` | `addresses()` Returns the list of IP addresses associated with `hostName()`.
`QHostInfo` | `clone()`
`QHostInfo.HostInfoError` | `error()` Returns the type of error that occurred if the host name lookup failed; otherwise returns `NoError` .
`java.lang.String` | `errorString()` If the lookup failed, this function returns a human readable description of the error; otherwise "Unknown error" is returned.
`static QHostInfo` | `fromName(java.lang.String name)` Looks up the IP address(es) for the given host `name`.
`java.lang.String` | `hostName()` Returns the name of the host whose IP addresses were looked up.
`static java.lang.String` | `localHostName()` Returns the host name of this machine.
`static int` | `lookupHost(java.lang.String name, QObject receiver, java.lang.String methodName)` Looks up the IP address(es) associated with host name `name`, and returns an ID for the lookup.
`static int` | `lookupHost(java.lang.String name, QSignalEmitter.Signal1 signal)` Looks up the IP address(es) associated with host name `name`, and returns an ID for the lookup.
`int` | `lookupId()` Returns the ID of this lookup.
`void` | `setAddresses(java.util.List addresses)` Sets the list of addresses in this QHostInfo to `addresses`.
`void` | `setError(QHostInfo.HostInfoError error)` Sets the error type of this QHostInfo to `error`.
`void` | `setErrorString(java.lang.String errorString)` Sets the human readable description of the error that occurred to `str` if the lookup failed.
`void` | `setHostName(java.lang.String name)` Sets the host name of this QHostInfo to `hostName`.
`void` | `setLookupId(int id)` Sets the ID of this lookup to `id`.

Methods inherited from class com.trolltech.qt.QtJambiObject
`dispose, disposed, equals, finalize, reassignNativeResources, tr, tr, tr`

Methods inherited from class com.trolltech.qt.QSignalEmitter
`blockSignals, disconnect, disconnect, signalsBlocked, signalSender, thread`

Methods inherited from class com.trolltech.qt.internal.QSignalEmitterInternal
`__qt_signalInitialization`

Methods inherited from class java.lang.Object
`getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Methods inherited from interface com.trolltech.qt.QtJambiInterface
`disableGarbageCollection, nativeId, nativePointer, reenableGarbageCollection, setJavaOwnership`

Constructor Detail

### QHostInfo

    public QHostInfo(QHostInfo d)

  Constructs a copy of `other`.

### QHostInfo

    public QHostInfo()

  Constructs an empty host info object with lookup ID `id`.

See also:
  `lookupId()`.

### QHostInfo

    public QHostInfo(int lookupId)

  Constructs an empty host info object with lookup ID `id`.

See also:
  `lookupId()`.

Method Detail

### addresses

    public final java.util.List addresses()

  Returns the list of IP addresses associated with `hostName()`. This list may be empty.

  Example:

              QHostInfo info = new QHostInfo();
              // ...
              if (!info.addresses().isEmpty()) {
              QHostAddress address = info.addresses().get(0);
              // use the first IP address
              }

See also:
  `setAddresses()`, `hostName()`, and `error()`.

### error

    public final QHostInfo.HostInfoError error()

  Returns the type of error that occurred if the host name lookup failed; otherwise returns `NoError` .

See also:
  `setError()`, and `errorString()`.

### errorString

    public final java.lang.String errorString()

  If the lookup failed, this function returns a human readable description of the error; otherwise "Unknown error" is returned.

See also:
  `setErrorString()`, and `error()`.

### hostName

    public final java.lang.String hostName()

  Returns the name of the host whose IP addresses were looked up.

See also:
  `setHostName()`, and `localHostName()`.

### lookupId

    public final int lookupId()

  Returns the ID of this lookup.

See also:
  `setLookupId()`, `abortHostLookup()`, and `hostName()`.

### setAddresses

    public final void setAddresses(java.util.List addresses)

  Sets the list of addresses in this QHostInfo to `addresses`.

See also:
  `addresses()`.

### setError

    public final void setError(QHostInfo.HostInfoError error)

  Sets the error type of this QHostInfo to `error`.

See also:
  `error()`, and `errorString()`.

### setErrorString

    public final void setErrorString(java.lang.String errorString)

  Sets the human readable description of the error that occurred to `str` if the lookup failed.

See also:
  `errorString()`, and `setError()`.

### setHostName

    public final void setHostName(java.lang.String name)

  Sets the host name of this QHostInfo to `hostName`.

See also:
  `hostName()`.

### setLookupId

    public final void setLookupId(int id)

  Sets the ID of this lookup to `id`.

See also:
  `lookupId()`, and `lookupHost()`.

### abortHostLookup

    public static void abortHostLookup(int lookupId)

  Aborts the host lookup with the ID `id`, as returned by `lookupHost()`.

See also:
  `lookupHost()`, and `lookupId()`.

### fromName

    public static QHostInfo fromName(java.lang.String name)

  Looks up the IP address(es) for the given host `name`. The function blocks during the lookup which means that execution of the program is suspended until the results of the lookup are ready. Returns the result of the lookup in a QHostInfo object.

  If you pass a literal IP address to `name` instead of a host name, QHostInfo will search for the domain name for the IP (i.e., QHostInfo will perform a reverse lookup). On success, the returned QHostInfo will contain both the resolved domain name and IP addresses for the host name.

See also:
  `lookupHost()`.

### localHostName

    public static java.lang.String localHostName()

  Returns the host name of this machine.

See also:
  `hostName()`.

### lookupHost

    public static int lookupHost(java.lang.String name,
                                 QObject receiver,
                                 java.lang.String methodName)

  Looks up the IP address(es) associated with host name `name`, and returns an ID for the lookup. When the result of the lookup is ready, the specified method in `receiver` is called with a `QHostInfo` argument. The `QHostInfo` object can then be inspected to get the results of the lookup.

  Parameters:
    `name` - The host name.
    `receiver` - The object on which the method will be called.
    `methodName` - The name of a method which takes a single `QHostInfo` argument.

### lookupHost

    public static int lookupHost(java.lang.String name,
                                 QSignalEmitter.Signal1 signal)

  Looks up the IP address(es) associated with host name `name`, and returns an ID for the lookup. When the result of the lookup is ready, the specified signal is emitted with a `QHostInfo` argument. The `QHostInfo` object can then be inspected to get the results of the lookup.

  Parameters:
    `name` - The host name.
    `signal` - The signal to emit. Must take a single `QHostInfo` argument, and must be contained in a `QObject` subclass.

### clone

    public QHostInfo clone()

  Overrides:
    `clone` in class `java.lang.Object`

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