使用anyMatch无法解析方法startsWith

Question

Can some one tell me please what is wrong here. My code is fine until I added this portion of code if (!tmp.isEmpty()) { return e.isEmpty(); } The error is: Cannot resolve method startsWith(java.lang.String)

@Test
    public void TestData() {
        ArrayList<String> rootOpts = new ArrayList<String>();
        rootOpts.add("aa");
        rootOpts.add("bb");
        rootOpts.add("ac");
        ArrayList<String> allSiblings = new ArrayList<String>();
        allSiblings.add("aa");
        allSiblings.add("ac");
        allSiblings.add("abc");

        System.out.println("allMatch " + rootOpts.stream()
                .map((e) -> {
                    System.out.println("e = " + e);
                    List<String> tmp = new ArrayList<String>();
                    tmp.addAll(allSiblings);
                    String[] CHs = {"ab","aa","ac"};
                    for (String chh : CHs) {
                        tmp.remove(chh);
                    }
                    if (!tmp.isEmpty()) {
                        return e.isEmpty();
                    }
                    return e;
                })
                .anyMatch(v -> v.startsWith("a")));
    }

I am trying to rewrite the following code below(this code is contained in a method that is supposed to return a boolean value true or false):

for (Option e : rootOpts) {
            List<String> tmp = new ArrayList<String>();
            tmp.addAll(allSiblings);
            if (e.getData() != null && !e.getData().getString().isEmpty()) {
                String[] chs = {"ab","aa","ac"};
                for (String ch : chs) {
                    tmp.remove(ch);
                }
            } else {
                return false;
            }
            if (!tmp.isEmpty()) {
                return false;
            }
        }
        return true;

Thank you for your help guys

Answer 1

e.isEmpty() returns a boolean . In the following method anyMatch you want to invoke the method startsWith on this boolean but this method does not exist on boolean . So change your code to:

            if (!tmp.isEmpty()) {
                return ""; //or whatever string makes sense
            }

Answer 2

e is of type String while e.isEmpty() is of type Boolean .

Therefore the return type of your function is Object .

Finally, Object does not have a startsWith function, contrary to the original String type that was returned which is why the compiler is complaining.

Answer 3

Look at the return type of isEmpty() - it's boolean . How are you planning to do startsWith on a boolean true/false ? :) Stream predicts that it's possible to get boolean, and thus it cannot let you do startsWith on it.

if (!tmp.isEmpty()) {
    return e.isEmpty();
}