button01.setOnClickListener(new Button.OnClickListener(){
    @Override
    public void onClick(View v) {
        final String username = edit_account.getText().toString();
        final String password = edit_password.getText().toString();
        txt.setText("帳號資訊:" + username + "/" + password);

        Thread t = new Thread(new Runnable(){
            @Override
            public void run() {
                str = doQuery(username, password);
            }
        });
        t.start();
        ...............................................
        ...............................................
    }
});