java - 使用 Qr 扫描仪扫描无效字符串时我的应用程序崩溃

Question

我是 android 初学者...通过 qr 扫描仪我正在扫描数据...代码正在运行好吧...假设如果我扫描像 abc 这样的字符串...我的应用程序正在崩溃...因为字符较少...如何避免崩溃...如果我扫描下面代码中的一些无效字符串...任何人都可以帮忙我...

  public void onActivityResult(int requestCode, int resultCode, Intent data) {
    //    super.onActivityResult(requestCode, resultCode, data);
    if (requestCode == 0) {
        if (resultCode == Activity.RESULT_OK) {
            String contents = data.getStringExtra("SCAN_RESULT");

            String Id = contents.substring(0, 10),
                    password = contents.substring(10, 14);
            //    formatTxt.setText("FORMAT: " + contents);
            //  contentTxt.setText("CONTENT: " + format);

            Toast toast = Toast.makeText(getActivity(), "" + contents, Toast.LENGTH_LONG);
            toast.show();
          setdetails(id.toString(), password.toString());



      } else if (resultCode == Activity.RESULT_CANCELED) {
      // Handle cancel
       Toast toast = Toast.makeText(getActivity(), " Cancelled", Toast.LENGTH_SHORT);

       toast.show();

  }

    } else
        super.onActivityResult(requestCode, resultCode, data);
}

java.lang.RuntimeException: Failure delivering result ResultInfo{who=android:fragment:0, request=0, result=-1, data=Intent { act=com.google.zxing.client.android.SCAN flg=0x80000 (has extras) }} to activity {com.application}: java.lang.StringIndexOutOfBoundsException: length=7; regionStart=0; regionLength=10

                                                                           at android.app.ActivityThread.deliverResults(ActivityThread.java:3720)
                                                                          Caused by: java.lang.StringIndexOutOfBoundsException: length=7; regionStart=0; regionLength=10

Answer 1

你需要确保字符串长度不小于14(在你的情况下)而且它也不为空使用此代码:

//...some code ...
String contents = data.getStringExtra("SCAN_RESULT");
if(contents!=null && contents.length() >= 14){
    String Id = contents.substring(0, 10),
    password = contents.substring(10, 14);
    //    formatTxt.setText("FORMAT: " + contents);
    //  contentTxt.setText("CONTENT: " + format);

    Toast toast = Toast.makeText(getActivity(), "" + contents, Toast.LENGTH_LONG);
    toast.show();
    setdetails(id.toString(), password.toString());   
}else{
    Toast toast = Toast.makeText(getActivity(), "Invalid Data", Toast.LENGTH_LONG);
    toast.show();
}