For High-Performance on an Instance Field, Use the Double-Check Idiom

LazyField.java

private volatile FieldType field;

FieldType getField() {
    
    FieldType result = field;
    
    if (result == null) { // 1st check (no lock)
        synchronized (this) {
            result = field;
            if (result == null) // 2nd check (w/ lock)
            field = result = computeFieldValue();
        }
    }
    
    return result;
}