When accessing Java/Kotlin code from a C# script in Unity, you can pass certain data types. The following table outlines the data types you can send between Java/Kotlin code and C# script, and the ones that you cannot.
| Supported data types | Unsupported data types |
|---|---|
|
|
The following code examples demonstrate how you can send all the supported data types between Java and C# code. You can save these Java and C# code files anywhere in your Unity project.
The following C# script uses AndroidJavaClass to call the Java functions to transfer variable data.
using UnityEngine;
public class TransferTypes : MonoBehaviour
{
void Start()
{
using (AndroidJavaClass pluginClass = new AndroidJavaClass("com.unity3d.player.JavaTransferTypesExample"))
{
//Receive data from Java functions
Debug.Log($"Received from Java Byte: " + pluginClass.CallStatic<sbyte>("getByte"));
Debug.Log($"Received from Java Short: " + pluginClass.CallStatic<short>("getShort"));
Debug.Log($"Received from Java Int: " + pluginClass.CallStatic<int>("getInt"));
Debug.Log($"Received from Java Long: " + pluginClass.CallStatic<long>("getLong"));
Debug.Log($"Received from Java Float: " + pluginClass.CallStatic<float>("getFloat"));
Debug.Log($"Received from Java Double: " + pluginClass.CallStatic<double>("getDouble"));
Debug.Log($"Received from Java Boolean: " + pluginClass.CallStatic<bool>("getBoolean"));
Debug.Log($"Received from Java Char: " + pluginClass.CallStatic<char>("getChar"));
Debug.Log($"Received from Java String: " + pluginClass.CallStatic<string>("getString"));
//Send data to Java functions
pluginClass.CallStatic("setByte", (sbyte)9);
pluginClass.CallStatic("setShort", (short)87);
pluginClass.CallStatic("setInt", 6);
pluginClass.CallStatic("setLong", (long)5);
pluginClass.CallStatic("setFloat", 4.32f);
pluginClass.CallStatic("setDouble", 9.987);
pluginClass.CallStatic("setBoolean", false);
pluginClass.CallStatic("setChar", 'b');
pluginClass.CallStatic("setString", "This string is sent from C#");
}
}
}
The following Java code provides functions that the C# script calls to transfer data.
package com.unity3d.player;
public class JavaTransferTypesExample {
// Java functions to send data
public static byte getByte() {
return 12;
}
public static short getShort() {
return 34;
}
public static int getInt() {
return 5;
}
public static long getLong() {
return 6;
}
public static float getFloat() {
return 7.89f;
}
public static double getDouble() {
return 1.123;
}
public static boolean getBoolean() {
return true;
}
public static char getChar() {
return 'a';
}
public static String getString() {
return "This string is sent from Java";
}
//Java functions to receive data
public static void setByte(byte value) {
android.util.Log.i("Example", "Received from C# Byte: " + value);
}
public static void setShort(short value) {
android.util.Log.i("Example", "Received from C# Short: " + value);
}
public static void setInt(int value) {
android.util.Log.i("Example", "Received from C# Int: " + value);
}
public static void setLong(long value) {
android.util.Log.i("Example", "Received from C# Long: " + value);
}
public static void setFloat(float value) {
android.util.Log.i("Example", "Received from C# Float: " + value);
}
public static void setDouble(double value) {
android.util.Log.i("Example", "Received from C# Double: " + value);
}
public static void setBoolean(boolean value) {
android.util.Log.i("Example", "Received from C# Boolean: " + value);
}
public static void setChar(char value) {
android.util.Log.i("Example", "Received from C# Char: " + value);
}
public static void setString(String value) {
android.util.Log.i("Example", "Received from C# String: " + value);
}
}
The following C# script calls the Java functions to transfer complex data types, such as class/object.
using UnityEngine;
using System;
public class PassComplexStructure : MonoBehaviour
{
[Serializable]
public class DataTypes
{
public int number;
public float floatNumber;
public bool boolValue;
public string phrase;
}
void Start()
{
var example = new DataTypes
{
number = 123,
floatNumber = 4.56f,
boolValue = true,
phrase = "Testing passing an object from C# - successful"
};
using var pluginClass = new AndroidJavaClass("com.unity3d.player.JavaPassObject");
var jsonString = JsonUtility.ToJson(example);
pluginClass.CallStatic("setDataSet", jsonString);
var jsonFromJava = pluginClass.CallStatic<string>("getDataSet");
var receivedData = JsonUtility.FromJson<DataTypes>(jsonFromJava);
Debug.Log($@"C# Deserialized from Java JSON: Number: {receivedData.number}, Float: {receivedData.floatNumber}, Bool: {receivedData.boolValue}, String: {receivedData.phrase}");
}
}
The following Java code provides functions that the C# script calls.
package com.unity3d.player;
import org.json.JSONException;
import org.json.JSONObject;
public class JavaPassObject {
public static class DataTypes
{
public int number;
public float floatNumber;
public boolean boolValue;
public String phrase;
public DataTypes(int number, float floatNumber, boolean boolValue, String phrase) {
this.number = number;
this.floatNumber = floatNumber;
this.boolValue = boolValue;
this.phrase = phrase;
}
@Override
public String toString() {
return "Java Deserialized from C# JSON:" +
" Number: " + number +
", Float: " + floatNumber +
", Bool: " + boolValue +
", String: " + phrase;
}
}
public static void setDataSet(String value)
{
try {
var jsonObject = new JSONObject(value);
int number = (int) jsonObject.getInt("number");
float floatNumber = (float) jsonObject.getDouble("floatNumber");
boolean boolValue = (boolean) jsonObject.getBoolean("boolValue");
String phrase = (String) jsonObject.getString("phrase");
var receivedData = new DataTypes(number, floatNumber, boolValue, phrase);
android.util.Log.i("Test", receivedData.toString());
} catch (JSONException e) {
System.err.println("Error parsing JSON: " + e.getMessage());
}
}
public static String getDataSet() throws JSONException
{
var example = new DataTypes(987, 6.54f, false, "Testing passing an object from Java - successful");
var jsonObject = new JSONObject();
jsonObject.put("number", example.number);
jsonObject.put("floatNumber", example.floatNumber);
jsonObject.put("boolValue", example.boolValue);
jsonObject.put("phrase", example.phrase);
return jsonObject.toString();
}
}