Java Combining assert statement and instanceof pattern matching

AssertPatternMatching.java

public class AssertPatternMatching {
    public static void main(String[] args) {
        Object obj = args.length == 0 ? Integer.valueOf(42) : "Hello";

        afterAssert(obj);
        insideMessage(obj);
    }

    private static void afterAssert(Object obj) {
        assert obj instanceof String str;
        str.length();
    }

    private static void insideMessage(Object obj) {
        assert !(obj instanceof String str) : "Is a string: " + str.length();
        obj.hashCode();
    }

    private static void afterAssertIf(Object obj) {
        if(obj instanceof String str) {
            str.length();
        } else {
            throw new AssertionError();
        }
    }

    private static void insideMessageIf(Object obj) {
        if (!(obj instanceof String str)) {
            obj.hashCode();
        } else {
            throw new AssertionError("Is a string: "+ str.length());
        }
    }
}