在找到anagram时，程序在if else语句中崩溃

Question

在下面的代码中，我试图从用户那里获取一个输入，如果用户输入了一个像？AEIRST的输入？由A-Z中的字母替换，然后从文件中检查字谜。但程序崩溃了。请帮忙。

以下是程序崩溃的部分的代码片段：

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    anagram=(EditText)findViewById(R.id.inputtext);
    submit=(Button)findViewById(R.id.submit);
    viewall=(TextView)findViewById(R.id.list);
    viewall.setMovementMethod(new ScrollingMovementMethod());
    submit.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            String a =anagram.getText().toString();
            checkword("cswfifteen.txt",a);



        }
    });

}
private void checkword(String Filename,  String a) {

    StringBuilder builder = null;
    BufferedReader reader = null;
    ArrayList<String> words = new ArrayList<>();

    try {
        builder = new StringBuilder();
        reader = new BufferedReader(new InputStreamReader(
                getAssets().open(Filename)

        ));


        String Line;
        while ((Line = reader.readLine()) != null) {

            builder.append(Line).append("\n");

        }
        String[] dict = builder.toString().split("\n");
        if (a.matches("[?]+")) {


            for (String i : dict) {


                char[] b = i.toString().toCharArray();
                Arrays.sort(b);

                char[] c = a.toCharArray();
                Arrays.sort(c);
                if (b.length == a.length()) {
                    words.add(i);
                }
            }
        } else if (a.indexOf("?")!=-1) {
            for (String i : dict) {

            for (char j : alphabets) {
                a = a.replace('?', j);
                char[] c=a.toUpperCase().toCharArray();
                Arrays.sort(c);
                viewall.setText(String.valueOf(c));

                char[] b = i.toString().toCharArray();
                Arrays.sort(b);
                    if (String.valueOf(b).contains(String.valueOf(c)) && b.length==c.length) {
                        words.add(i);
                    }
                }
            }
        } else {
            for (String i : dict) {


                char[] b = i.toString().toCharArray();
                Arrays.sort(b);

                char[] c = a.toUpperCase().toCharArray();
                Arrays.sort(c);
                if (String.valueOf(b).contains(String.valueOf(c)) && b.length==c.length) {
                    words.add(i);
                }
            }

        }


        Collections.sort(words);
        StringBuilder result = new StringBuilder();
            for (String i : words)
            {

                result.append(i + "\n");
            }
            viewall.setText(result.toString());


    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            reader.close();
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}