import org.checkerframework.checker.nullness.qual.Nullable;
import org.checkerframework.common.value.qual.IntVal;
import org.checkerframework.common.value.qual.StringVal;

public class StringValNull {

    public static void main(String[] args) {
        @StringVal("itsValue") String nbleString = null;
        @StringVal("itsValue") String nnString = "itsValue";

        System.out.println(toString1(nbleString));
        System.out.println(toString2(nbleString));

        System.out.println(toString1(nnString));
        System.out.println(toString2(nnString));
        // System.out.println(toString3(nnString));

        @IntVal(22) Integer nbleInteger = null;
        @IntVal(22) Integer nnInteger = 22;

        System.out.println(toString4(nbleInteger));
        System.out.println(toString5(nbleInteger));

        System.out.println(toString4(nnInteger));
        System.out.println(toString5(nnInteger));
        System.out.println(toString6(nnInteger));
    }

    static @StringVal("arg=itsValue") String toString1(
            @Nullable @StringVal("itsValue") String arg) {
        // :: error: (return.type.incompatible)
        return "arg=" + arg;
    }

    static @StringVal({"arg=itsValue", "arg=null"}) String toString2(
            @Nullable @StringVal("itsValue") String arg) {
        return "arg=" + arg;
    }

    /* static @StringVal("arg=itsValue") String toString3(@StringVal("itsValue") String arg) {
        return "arg=" + arg;
    } */

    static @StringVal("arg=22") String toString4(@Nullable @IntVal(22) Integer arg) {
        // :: error: (return.type.incompatible)
        return "arg=" + arg;
    }

    static @StringVal({"arg=22", "arg=null"}) String toString5(@Nullable @IntVal(22) Integer arg) {
        return "arg=" + arg;
    }

    static @StringVal("arg=22") String toString6(@IntVal(22) int arg) {
        return "arg=" + arg;
    }

    final @StringVal("hello") String s = null;

    @StringVal("hello") String s2 = null;

    void method2(StringValNull obj) {
        // :: error: (assignment.type.incompatible)
        @StringVal("hello") String l1 = "" + obj.s;
        // :: error: (assignment.type.incompatible)
        @StringVal("hello") String l2 = "" + obj.s2;
    }
}