# [Bld](https://github.com/rife2/rife2/wiki/What-Is-Bld) Extension to Create or Modify Properties Files
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[](https://www.oracle.com/java/technologies/javase/jdk17-archive-downloads.html)
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A `bld` extension for creating or modifying [property files](https://docs.oracle.com/javase/tutorial/essential/environment/properties.html) with [bld](https://github.com/rife2/rife2/wiki/What-Is-Bld). It is inspired by the [ant PropertyFile task](https://ant.apache.org/manual/Tasks/propertyfile.html).
```java
@BuildCommand
public void updateMajor() throws Exception {
new PropertyFileOperation(this)
.file("version.properties")
.entry(new Entry("version.major", Types.INT).defaultValue(0).calc(ADD))
.entry(new Entry("version.minor").set(0))
.entry(new Entry("version.patch").set(0))
.entry(new Entry("build.date", Types.DATE).set("now").pattern("yyyy-MM-dd"))
.execute();
}
```
Invoking the `updateMajor` command, will create the `version.propertees`file:
```sh
./bld updateMajor ...
```
```ini
# version.properties
build.date=2023-04-02
version.major=1
version.minor=0
version.patch=0
```
Invoking the `updateMajor` command again, will increase the `version.major` property:
```sh
./bld updateMajor ...
```
```ini
# version.properties
build.date=2023-04-02
version.major=2
version.minor=0
version.patch=0
```
- [View Examples](https://github.com/rife2/bld-property-file/tree/master/examples)
## Property File
The [PropertyFileOperation](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/PropertyFileOperation.html) class is used to configure the [properties file](https://docs.oracle.com/javase/tutorial/essential/environment/properties.html) location, etc.
| Function | Description | Required |
|:------------------|:----------------------------------------------------------------|:---------|
| `file()` | The location of the properties files to modify. | Yes |
| `comment()` | Comment to be inserted at the top of the properties file. | No |
| `failOnWarning()` | If set to `true`, will cause execution to fail on any warnings. | No |
## Entry
The [Entry](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.html) class is used to specify modifications to be made to the [properties file](https://docs.oracle.com/javase/tutorial/essential/environment/properties.html).
| Function | Description |
|:-----------------|:-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| `key()` | The name of the property name/value pair. |
| `set()` | The value to set the property to, regardless of its previous value. |
| `type()` | The value datatype, either [Types.INT](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Types.html), [Types.DATE](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Types.html), or [Types.STRING](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Types.html). If none specified, [Types.STRING](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Types.html) is assumed. |
| `pattern()` | For [Types.INT](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Types.html) and [Types.DATE](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Types.html) only. If present, will parse the value as [DecimalFormat](https://docs.oracle.com/javase/7/docs/api/java/text/DecimalFormat.html) or [SimpleDateFormat](https://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html) patterns, respectively. |
| `unit()` | The unit value to be used with [Types.DATE](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Types.html) calculations. See [Units](#units). |
- For convenience the `key` (and optional `type`) is first set in the constructor.
- `key` is required. `value` or `defaultValue` are required except when deleting.
- For [Types.DATE](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Types.html), the `now` keyword can be used as the property value.
## Functions
The following function are available:
| Function | Example | Description |
|:-----------|:--------------------------------------------------------------------------------------------------------|:-------------------------------------------|
| `calc()` | `calc(ADD)`
`calc(v -> v + 1)`
`calc(SUB)`
`calc(v -> v - 1)` | Perform a calculation with an entry value. |
| `modify()` | `modify("-foo", String::concat)`
`modify("-foo", (v, s) -> v + s)`
`modify((v, s) -> v.trim())` | Modify an entry value. |
| `delete()` | `delete()` | Delete an entry. |
## Units
The following [Units](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Units.html) are available for [Types.DATE](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Types.html):
* `Units.MILLISECOND`
* `Units.SECOND`
* `Units.MINUTE`
* `Units.HOUR`
* `Units.DAY`
* `Units.WEEK`
* `Units.MONTH`
* `Units.YEAR`
## Differences with the [ant PropertyFile task](https://ant.apache.org/manual/Tasks/propertyfile.html)
* The comments and layout of the original property file will not be preserved.
* The `jdkproperties` parameter is not implemented.
* The default [Types.DATE](https://rife2.github.io/bld-property-file/rife/bld/extension/propertyfile/Entry.Types.html) pattern is `yyyy-MM-dd HH:mm` and not `yyyy/MM/dd HH:mm`.