# Apache Beam: ToString Transform

## Overview

If you want to convert every input element from a PCollection to a string, you should check out the `ToString` transforms. It can do everything from simply converting an object to a string by implicitly calling its `toString()` method to concatenate a kv pair with a custom delimiter.

## When You Should Use the ToString Transform

You should use the `ToString` transforms when you want to perform the following transformations on your input data:

1. Transform each element into a string using the `Object.toString()` method
    
2. Transform an input element of type `Iterables` into a string using a delimiter
    
3. Transform an input element of type `KV` into a string using a delimiter
    

## How to Use the ToString Transform

Just apply the built-in transform to a PCollection of elements, lists, or KVs. The output PCollection will always have the type of the `String`.

## Example: Convert KV to String

```java
    // Create key-value pairs
    PCollection<KV<String, String>> pairs =
        pipeline.apply(
            Create.of(
                KV.of("fall", "apple"),
                KV.of("spring", "strawberry"),
                KV.of("winter", "orange"),
                KV.of("summer", "peach"),
                KV.of("spring", "cherry"),
                KV.of("fall", "pear")));
    // Use ToString on key-value pairs
    PCollection<String> result = pairs.apply(ToString.kvs());

    // results in a PCollection containing
    // fall,apple
    // string,strawberry
    // ...etc
```

## Conclusion

Check out other useful transforms from the [official Apache Beam documentation](https://beam.apache.org/documentation/transforms/java/overview/).