> For the complete documentation index, see [llms.txt](https://oci-pronghorn.gitbook.io/pronghorn/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://oci-pronghorn.gitbook.io/pronghorn/chapter-5-utility-classes/appendables.md).

# Appendables

In order to allow for mostly garbage-free behavior, standard Java string concatenation using the “+” operator is not ideal. Pronghorn has its own Appendables class that allows for garbage-free, single pass creation of text.

The API follows a fluent pattern where every method returns the same Appendable which was passed in. It is located in `PronghornPipes`.

#### Examples <a href="#examples" id="examples"></a>

**Append Array**

Append an array to a StringBuilder

```java
byte[] a = new byte[1000];
Random r = new Random(101);
r.nextBytes(a);
StringBuilder str = new StringBuilder();
Appendables.appendArray(str, a);
```

**Append Value**

Append value(s) to an existing StringBuilder

```java
StringBuilder str = new StringBuilder();
Appendables.appendValue(str, "Label: ", 5, " -Suffix");
```

**Append Fixed Decimal Digits**

Append fixed decimals to a StringBuilder

```java
StringBuilder str = new StringBuilder();
Appendables.appendFixedDecimalDigits(str, -42,10 );
```

**Append Base64-encoded String**

Creates a Base64-encoded String and appends it

```java
String value = "Man is distinguished, not only by his reason, but by this singular passion from "
	    	+"other animals, which is a lust of the mind, that by a perseverance of delight "
	    	+"in the continued and indefatigable generation of knowledge, exceeds the short "
	    	+"vehemence of any carnal pleasure.";

byte[] b = value.getBytes();

StringBuilder str = new StringBuilder();
Appendables.appendBase64(str, b, 0, b.length, Integer.MAX_VALUE);
```

**Append Base64-decoded String**

Decodes a Base64 string and writes it to target

```java
String value = "TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb24sIGJ1dCBieSB0aGlz"
               +"IHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBhbmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2Yg"
               +"dGhlIG1pbmQsIHRoYXQgYnkgYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGlu"
               +"dWVkIGFuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBleGNlZWRzIHRo"
               +"ZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVhc3VyZS4=";

byte[] encBytes = value.getBytes();
byte[] target = new byte[value.length()];

Appendables.decodeBase64(encBytes, 0, encBytes.length, Integer.MAX_VALUE, target, 0, Integer.MAX_VALUE);
```

**Append Epoch Time**

Append an epoch time to a string

```java
StringBuilder str = new StringBuilder();
Appendables.appendEpochTime(str, 10000); //10 seconds
```

**Append Hex Value**

Convert an integer to its hex value and append that to the StringBuilder

```java
StringBuilder str = new StringBuilder();
int value = 400;

Appendables.appendHexDigits(str, value);
```

**Append Hex Fixed Value**

Convert an integer to its fixed hex value and append that to the StringBuilder

```java
StringBuilder str = new StringBuilder();
int value = 400;
int bits = 8;

Appendables.appendFixedHexDigits(str, value, bits);
```

**Append Hex Array**

Add hex array to the StringBuilder

```java
int[] a = new int[1000];
Random rand = new Random(101);

byte [] b = new byte[1000];
rand.nextBytes(b);

for(int i = 0;i<a.length;i++){
  a[i] = rand.nextInt(0x10) + 0x10;  // Generates a random number between 0x10 and 0x20
}

StringBuilder str = new StringBuilder();
Appendables.appendHexArray(str, 'L', a, 0, 0xFF, 'R', a.length);
```