MethodTypeVars7.java

// Test case based on checker-framework discuss mailing list discussion
// "Generics problem with @Nullable method parameter" from May 16, 2014
// https://groups.google.com/d/msg/checker-framework-discuss/-gPGQ7mHjYI/YxCtjjBWx5cJ

import org.checkerframework.checker.nullness.qual.*;

abstract class MethodTypeVars7 {

    abstract <T> T val(@Nullable T value, T defaultValue);

    void tests(@Nullable String t1, @NonNull String t2) {
        @Nullable String s3 = val(t1, null);
    }

    <T> T validate(@Nullable T value, T defaultValue) {
        return value != null && !value.toString().isEmpty() ? value : defaultValue;
    }

    <T> T validateIf(@Nullable T value, T defaultValue) {
        if (value != null && !value.toString().isEmpty()) {
            return value;
        } else {
            return defaultValue;
        }
    }

    <T> T validate2(@Nullable T value, T defaultValue) {
        return value == null || value.toString().isEmpty() ? defaultValue : value;
    }

    <T> T validate3(@Nullable T value, T defaultValue) {
        return value != null ? value : defaultValue;
    }

    <T> T validate4(@Nullable T value, T defaultValue) {
        return value == null ? defaultValue : value;
    }

    <T> T validatefail(@Nullable T value, T defaultValue) {
        //:: error: (return.type.incompatible)
        return ((value == null || !value.toString().isEmpty()) ? value : defaultValue);
    }

    <T> T validate2fail(@Nullable T value, T defaultValue) {
        //:: error: (return.type.incompatible)
        return ((value != null && value.toString().isEmpty()) ? defaultValue : value);
    }

    <T> T validate3fail(@Nullable T value3, T defaultValue3) {
        //:: error: (return.type.incompatible)
        return value3 == null ? value3 : defaultValue3;
    }

    <T> T validate4fail(@Nullable T value, T defaultValue) {
        //:: error: (return.type.incompatible)
        return value != null ? defaultValue : value;
    }

    String test1(@Nullable String t1, @NonNull String t2) {
        @Nullable String s1 = validate(t1, null);
        @Nullable String s2 = validate(t2, null);
        @NonNull String s3 = validate(t1, "N/A");
        @NonNull String s4 = validate(t2, "N/A");
        return "[" + s1 + "\t" + s2 + "\t" + s3 + "\t" + s4 + "]";
    }

    String test2(@Nullable String t1, @NonNull String t2) {
        @Nullable String s1 = validate(t1, t1);
        @Nullable String s2 = validate(t2, t1);
        @NonNull String s3 = validate(t1, t2);
        @NonNull String s4 = validate(t2, t2);
        return "[" + s1 + "\t" + s2 + "\t" + s3 + "\t" + s4 + "]";
    }

    void main(String[] args) {
        System.out.println("test 1 " + test1("s_1", "s_2"));
        System.out.println("test 2 " + test2("s_1", "s_2"));
        System.out.println("test 1 " + test1(null, "s_2"));
        System.out.println("test 2 " + test2(null, "s_2"));
    }
}