# Debug Logs

> Log is the most important part of the debugging process, `YukiHookAPI` encapsulates a set of stable and efficient debugging log functions for developers.

## Normal Logs

You can call `YLog.debug`, `YLog.info`, `YLog.warn` to print normal logs to the console.

The usage method is as follows.

> The following example

```kotlin
YLog.debug(msg = "This is a log")
```

At this ponit, `YukiHookAPI` will call `android.util.Log` and log function in (Xposed) Host environment to print this log at the same time.

The default `TAG` of the log is the value you set in `YLog.Configs.tag`.

You can also customize this value dynamically, but it is not recommended to modify `TAG` easily to prevent logs from being filtered.

> The following example

```kotlin
YLog.debug(tag = "YukiHookAPI", msg = "This is a log")
```

The printed result is as shown below.

> The following example

```:no-line-numbers
[YukiHookAPI][D][host package name] This is a log
```

You can also use `YLog.EnvType` to customize the type of log printing.

You can choose to use `android.util.Log` or the log function in the (Xposed) Host environment to print logs.

The default type is `YLog.EnvType.BOTH`, which means that both methods are used to print logs.

For example we only use `android.util.Log` to print logs.

> The following example

```kotlin
YLog.debug(tag = "YukiHookAPI", msg = "This is a log", env = YLog.EnvType.LOGD)
```

Or just use the log function that in the (Xposed) Host environment to print the log, this method can only be used in the (Xposed) Host environment.

> The following example

```kotlin
YLog.debug(tag = "YukiHookAPI", msg = "This is a log", env = YLog.EnvType.XPOSED_ENVIRONMENT)
```

If you want to intelligently distinguish the (Xposed) Host environment from the Module environment, you can write it in the following form.

> The following example

```kotlin
YLog.debug(tag = "YukiHookAPI", msg = "This is a log", env = YLog.EnvType.SCOPE)
```

In this way, the API will intelligently select the specified method type to print this log in different environments.

::: tip

For more functions, please refer to [YLog.debug](../public/com/highcapable/yukihookapi/hook/log/YLog#debug-method), [YLog.info](../public/com/highcapable/yukihookapi/hook/log/YLog#info-method) and [YLog.warn](../public/com/highcapable/yukihookapi/hook/log/YLog#warn-method) methods.

:::

## Error Logs

You can call `YLog.error` to print `E` level logs to the console.

The usage method is as follows.

> The following example

```kotlin
YLog.error(msg = "This is an error")
```

The error log is the highest level, regardless of whether you have filtered only `E` level logs.

For error-level logging, you can also append an exception stack.

```kotlin
// Assume this is the exception that was thrown
val throwable = Throwable(...)
// Print log
YLog.error(msg = "This is an error", e = throwable)
```

The printed result is as shown below.

> The following example

```:no-line-numbers
[YukiHookAPI][E][host package name] This is an error
```

At the same time, the log will help you print the entire exception stack.

> The following example

```:no-line-numbers
java.lang.Throwable
    at com.demo.Test.<init>(...)
    at com.demo.Test.doTask(...)
    at com.demo.Test.stop(...)
    at com.demo.Test.init(...)
    at a.a.a(...)
    ... 3 more
```

In the error log, you can also use `YLog.EnvType` to specify the method type currently used to print the log.

::: tip

For more functions, please refer to the [YLog.error](../public/com/highcapable/yukihookapi/hook/log/YLog#error-method) method.

:::

## Save Logs and Custom Elements

You can save all currently printed logs directly to a file using the `YLog.saveToFile` method.

> The following example

```kotlin
// Please note
// The saved file path must have read and write permissions
// Otherwise an exception will be thrown
YLog.saveToFile("/sdcard/Documents/debug_log.log")
```

You can also use `YLog.contents` to get all the log file contents that have been printed so far.

> The following example

```kotlin
// Get the contents of all log files that have been printed so far
val fileContent = YLog.contents
```

If you need an array of real-time log data structures, you can directly get the content of `YLog.inMemoryData`.

> The following example

```kotlin
// Get the currently printed real-time log data structure array
YLog.inMemoryData.forEach {
     it.timestamp // Get timestamp
     it.time // Get UTC time
     it.priority // Get priority
     it.msg // Get message
     it.throwable // Get exception
     // ...
}
```

If you want to format or save the obtained custom log data to a file, you only need to use the following method.

> The following example

```kotlin
// Assume this is the custom log data you get
val data: List<YLogData>
// Format log data to String
val dataString = YLog.contents(data)
// Save log data to file
// Please note
// The saved file path must have read and write permissions
// Otherwise an exception will be thrown
YLog.saveToFile("/sdcard/Documents/debug_log.log", data)
```

::: danger

You need to enable **YLog.Configs.isRecord** to get the contents of **YLog.inMemoryData**.

The obtained log data is isolated from each other in the Host App and the Module App's process.

You can only get the corresponding log data in the corresponding process.

If you need to get these log data in real time anywhere, please refer to [Xposed Module and Host Channel](xposed-channel), [Register Module App's Activity](host-inject#register-module-app-s-activity).

If you only want to get log data in real time through Module App or Host App, Please refer to the optional solution [YukiHookDataChannel.obtainLoggerInMemoryData](../public/com/highcapable/yukihookapi/hook/xposed/channel/YukiHookDataChannel#obtainloggerinmemorydata-method) method.

:::

You can also use `YLog.Configs.elements` to customize the elements that debug logs display externally.

This function requires `YukiHookAPI.Configs` to be configured in `onInit` of the Hook entry class.

> The following example

```kotlin
override fun onInit() = configs {
    debugLog {
        // ...
        elements(TAG, PRIORITY, PACKAGE_NAME, USER_ID)
    }
    // ...
}
```

::: tip

For more functions, please refer to [YLog.inMemoryData](../public/com/highcapable/yukihookapi/hook/log/YLog#inmemorydata-field), [YLog.contents](../public/com/highcapable/yukihookapi/hook/log/YLog#contents-field), [YLog.contents](../public/com/highcapable/yukihookapi/hook/log/YLog#contents-method), [YLog.saveToFile](../public/com/highcapable/yukihookapi/hook/log/YLog#savetofile-method) methods and [YLog.Configs](../public/com/highcapable/yukihookapi/hook/log/YLog#configs-object).

:::