Where (which properties file) does System.getProperty("key") reads from?

Question

My application uses String str = System.getProperty("key","default"); which always returns default because i am not able to set the key-value pair in the properties file.

I tried setting it in deployment.properties file located in users->appdata->locallow->sun->java>deployment and also directly putting key=value in runtime parameter in java control panel but not working.

Please help me to set it correctly or if there exist a different properties file where these values is to be set, kindly share the path ? I google it but couldn't find.Thanks in Advance

Edit: We use jeety server for deployment.And we have many properties file bundled with our souce code.

Answer 1

The Values are set using Native code in runtime. Its set inside the System.c, and a function called Java_java_lang_System_initProperties

Snippet

JNIEXPORT jobject JNICALL
Java_java_lang_System_initProperties(JNIEnv *env, jclass cla, jobject props)
{
    char buf[128];
    java_props_t *sprops = GetJavaProperties(env);
    jmethodID putID = (*env)->GetMethodID(env,
                                          (*env)->GetObjectClass(env, props),
                                          "put",
            "(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;");
    jmethodID removeID = (*env)->GetMethodID(env,
                                          (*env)->GetObjectClass(env, props),
                                          "remove",
            "(Ljava/lang/Object;)Ljava/lang/Object;");
    jmethodID getPropID = (*env)->GetMethodID(env,
                                          (*env)->GetObjectClass(env, props),
                                          "getProperty",
            "(Ljava/lang/String;)Ljava/lang/String;");
    jobject ret = NULL;
    jstring jVMVal = NULL;

    if (sprops == NULL || putID == NULL ) return NULL;

    PUTPROP(props, "java.specification.version",
            JDK_MAJOR_VERSION "." JDK_MINOR_VERSION);
    PUTPROP(props, "java.specification.name",
            "Java Platform API Specification");
    PUTPROP(props, "java.specification.vendor",
            JAVA_SPECIFICATION_VENDOR);

    PUTPROP(props, "java.version", RELEASE);
    PUTPROP(props, "java.vendor", VENDOR);
    PUTPROP(props, "java.vendor.url", VENDOR_URL);
    PUTPROP(props, "java.vendor.url.bug", VENDOR_URL_BUG);
    .......
    .......
    .......

Answer 2

Well, the System.getProperty(String) returns properties that relate to the global system of a JVM. Here you can find a list of available properties.

If you want to load a custom file of properties, you should load this file in your own properties object of which you can find an example here. You should keep this Properties object seperate of the system properties. You should never just load your custom properties into the system properties. (You could do this via System.setProperties(Properties).) This is like defining global variables which is a sign of poor program design.