Main.java

package org.example;

import com.ibm.as400.access.AS400ZonedDecimal;

import java.math.BigDecimal;
import java.nio.charset.Charset;

public class Main {
    // EBCDIC charset (IBM037)
    static Charset ebcdicCharset = Charset.forName("IBM037");
    public static void showEBCDICHexVal(byte[] bytes){
        for (byte b : bytes) {
            // Convert byte to hexadecimal string
            String hexValue = String.format("%02X", b);
            // Convert byte to EBCDIC character
            String ebcdicChar = new String(new byte[]{b}, ebcdicCharset);
            System.out.printf("Hex: %s, EBCDIC: %s%n", hexValue, ebcdicChar);
        }
    }


    public static void main(String[] args) {
        //BigDecimal nNum = new BigDecimal("-120");

        BigDecimal nNum = new BigDecimal("120");

        AS400ZonedDecimal converter = new AS400ZonedDecimal(3, 0);
        byte[] nNumBytesArray = converter.toBytes(nNum);

        // Display byte array in hexadecimal and EBCDIC decoded characters
        System.out.println("Hexadecimal and EBCDIC Representation:");
        showEBCDICHexVal(nNumBytesArray);
    } //main
} //class

Get 120 , output

120
Hex: F1, EBCDIC: 1
Hex: F2, EBCDIC: 2
Hex: F0, EBCDIC: 0

Not expected 12{

Main2.java

package org.example;

import java.math.BigDecimal;
import com.ibm.as400.access.AS400ZonedDecimal;
import java.nio.charset.Charset;

public class Main2 {
    // EBCDIC charset (IBM037)
    static Charset ebcdicCharset = Charset.forName("IBM037");
    public static void showEBCDICHexVal(byte[] bytes){
        for (byte b : bytes) {
            // Convert byte to hexadecimal string
            String hexValue = String.format("%02X", b);
            // Convert byte to EBCDIC character
            String ebcdicChar = new String(new byte[]{b}, ebcdicCharset);
            System.out.printf("Hex: %s, EBCDIC: %s%n", hexValue, ebcdicChar);
        }
    }
    public static void main(String[] args) throws Exception {
        // EBCDIC string "12}" representing the zoned decimal encoded -120
        //String ebcdicString = "12}";
        String ebcdicString = "12{";

        // EBCDIC charset (IBM037)
        Charset ebcdicCharset = Charset.forName("IBM037");

        // Convert the string to EBCDIC byte array
        byte[] ebcdicBytes = ebcdicString.getBytes(ebcdicCharset);

        showEBCDICHexVal(ebcdicBytes);

        // Interpret the byte array as a zoned decimal to convert it back to BigDecimal
        // AS400ZonedDecimal takes length and scale, here length is 3 (for 3 digits) and scale is 0 (no decimal places)
        AS400ZonedDecimal converter = new AS400ZonedDecimal(3, 0);

        // Convert byte array to BigDecimal
        BigDecimal result = (BigDecimal) converter.toObject(ebcdicBytes);

        // Print the result
        System.out.println("Converted BigDecimal: " + result);
    }
}

Input 12{ get 120

Hex: F1, EBCDIC: 1
Hex: F2, EBCDIC: 2
Hex: C0, EBCDIC: {
Converted BigDecimal: 120

compare

Hex: F1, EBCDIC: 1 | Hex: F1, EBCDIC: 1
Hex: F2, EBCDIC: 2 | Hex: F2, EBCDIC: 2
Hex: F0, EBCDIC: 0 | Hex: C0, EBCDIC: {

if input positive number, you must change FX to CX.
(X is 0,1,3,4,5,6,7,8,9)

hard code rule:

modify the last element of the byte array.

You can do it yourself.

Hex value F0 to C0, F1 to C1,…..

• Hex: F0 -> C0, EBCDIC: 0 -> {
• Hex: F1 -> C1, EBCDIC: 1 -> …

You can use put your string (12{) into Main2.java get output BigDecimal (120) to verify your encode string.

** Hard code test**

Main2.java

//byte[] ebcdicBytes = ebcdicString.getBytes(ebcdicCharset);

byte[] ebcdicBytes = {(byte)0xF1, (byte)0xF2, (byte)0xC1};

12A -> 121

Hex: F1, EBCDIC: 1
Hex: F2, EBCDIC: 2
Hex: C1, EBCDIC: A
Converted BigDecimal: 121

    // Custom method to convert BigDecimal to EBCDIC Zoned Decimal format
    public static byte[] convertToZonedDecimal(BigDecimal number) {
        // Convert the BigDecimal to string representation
        String numStr = number.abs().toPlainString();
        int length = numStr.length();

        // Create a byte array for the EBCDIC zoned decimal
        byte[] ebcdicBytes = new byte[length];

        // Fill the byte array with EBCDIC values for the digits
        for (int i = 0; i < length - 1; i++) {
            ebcdicBytes[i] = (byte) (0xF0 + (numStr.charAt(i) - '0'));
        }

        // Handle the last byte with the appropriate sign
        char lastChar = numStr.charAt(length - 1);
        if (number.signum() >= 0) {
            // Positive: Convert last digit with positive sign encoding
            ebcdicBytes[length - 1] = (byte) (0xC0 + (lastChar - '0'));  // Positive sign -> C0, C1, ..., C9
        } else {
            // Negative: Convert last digit with negative sign encoding
            ebcdicBytes[length - 1] = (byte) (0xD0 + (lastChar - '0'));  // Negative sign -> D0, D1, ..., D9
        }

        return ebcdicBytes;
    }

Your Code:

byte[] convertedBytesArray = converter.toBytes(new BigDecimal("-120"));

Use convertToZonedDecimal code:

byte[] convertedBytesArray = convertToZonedDecimal(new BigDecimal("-120"));

Final Answer:

Main.java

package org.example;

import com.ibm.as400.access.AS400ZonedDecimal;

import java.math.BigDecimal;
import java.nio.charset.Charset;

public class Main {
    // EBCDIC charset (IBM037)
    static Charset ebcdicCharset = Charset.forName("IBM037");

    // Custom method to convert BigDecimal to EBCDIC Zoned Decimal format
    public static byte[] convertToZonedDecimal(BigDecimal number) {
        // Convert the BigDecimal to string representation
        String numStr = number.abs().toPlainString();
        int length = numStr.length();

        // Create a byte array for the EBCDIC zoned decimal
        byte[] ebcdicBytes = new byte[length];

        // Fill the byte array with EBCDIC values for the digits
        for (int i = 0; i < length - 1; i++) {
            ebcdicBytes[i] = (byte) (0xF0 + (numStr.charAt(i) - '0'));
        }

        // Handle the last byte with the appropriate sign
        char lastChar = numStr.charAt(length - 1);
        if (number.signum() >= 0) {
            // Positive: Convert last digit with positive sign encoding
            ebcdicBytes[length - 1] = (byte) (0xC0 + (lastChar - '0'));  // Positive sign -> C0, C1, ..., C9
        } else {
            // Negative: Convert last digit with negative sign encoding
            ebcdicBytes[length - 1] = (byte) (0xD0 + (lastChar - '0'));  // Negative sign -> D0, D1, ..., D9
        }

        return ebcdicBytes;
    }
    public static void showEBCDICHexVal(byte[] bytes){
        for (byte b : bytes) {
            // Convert byte to hexadecimal string
            String hexValue = String.format("%02X", b);
            // Convert byte to EBCDIC character
            String ebcdicChar = new String(new byte[]{b}, ebcdicCharset);
            System.out.printf("Hex: %s, EBCDIC: %s%n", hexValue, ebcdicChar);
        }
    }


    public static void main(String[] args) {
        BigDecimal nNum = new BigDecimal("121");
        //AS400ZonedDecimal converter = new AS400ZonedDecimal(3, 0);
        //byte[] nNumBytesArray = converter.toBytes(nNum);
        byte[] nNumBytesArray = convertToZonedDecimal(nNum);
        // Display byte array in hexadecimal and EBCDIC decoded characters
        System.out.println("Hexadecimal and EBCDIC Representation:");
        showEBCDICHexVal(nNumBytesArray);
    } //main
} //class