Why does this code trigger a force close in Android?
`score.setText(Integer.parseInt((String) score.getText())+1);`
score is a TextView, and I am simply increasing the number by 1. I have predefined a String resource to be the initial number in the score TextView.
I am quite frustrated.
First off you should try breaking down your code so you can actually see what is going on with it.
Instead of
score.setText(Integer.parseInt((String) score.getText())+1);
try
String tmp = score.getText().toString();
int score;
score = Integer.parseInt(tmp) + 1;
score.setText(String.valueOf(score));
EDIT: Upon further reading of the documentation, setText has several overloads, one of which DOES take an int, but it takes the int of a resource ID. My guess is that your score is not a valid resource ID, thus crashing your application.
public final void setText (int resid)
Oh and as far as the frequent FC's when beginning Android Dev, it happens to the best of us. The key is to learn WHY the FC's happen, and have a LOT of patience.
mostly u need to do this
score.setText(Integer.parseInt(score.getText().toString())+1);
coz.. getText() returns a Editable Object which cannot be parsed to Integer. So it give NumberFormat Exception.
AndMake sure to set TextView,s Text to an integer initially..
try this way
score.setText(String.valueOf(Integer.parseInt(score.getText().toString())+1));
as you can pass the integer value that's why getting force the application
TextEdit.setText takes a CharSequence as input.
You are supplying an integer through Integer.parseInt((String) score.getText())+1
See, if converting it back to string and using it in setText helps.
You can convert an integer to string using Integer.toString.
PS: I am new to java myself.
The compiler should have ideally caught this error.
It's possible java uses some implicit type conversions from string to int.
Related
I am creating a calculator app in android. It should calculate anonymously whatever is on textBox. For e.g. I enter 1+2.5-5*8 in textBox. But when I call addition method the app gets crashed. Because the input is in string format and answer I want is in numeric format. I used string buffer. I tried in java that when I enter (1+1+3-1) in stringBuffer and I display using println() method it give correct answer but same does not happen with string buffer when I take that value from editText.
You have to convert string into integer or float.
Use Integer.parseInt("") method to covert to integer and Float.parseFloat("") to convert to float.
First of all welcome to StackOverFlow
It might help if you add code and the error log in the question
So I am gonna cover all the possible things that might be happening wrong in your program:
NumberFormatException- you might not be converting the string "12" into int 12 to do so use Interger.parseInt(your string buffer with number only here);
Try using a stack and a queue for your solution (google it you will get details)
You might be making a mistake in getting string from edittext it sometimes give NullPointerException
if above is not enough comment and add your code asap
I am making an android application where i got a set of strings that i load from SharedPreferences so that i can save the strings. The strings contain only numbers, but it is not an int value, its a string value. And i wounder how i can minus the numbers that's in there, becuase usually, i would have been using something like an int value = value - value; But that doesn't seem to work since it's a string and not an int value. How can i do this even though it's a string? I know i could use int values instead, but as i didn't think of this before now, when i'm almost done, it would be alot of work changing all of the code that's related to this. Please help me and thanks so much in advance!
You will have to convert your strings to ints first, then operate on them, then save the string back:
String value = preferences.getString("key:");
int intValue = Integer.valueOf(value);
intValue = intValue - 1;
preferences.edit().putString("key", Integer.toString(intValue)).commit();
Try using Integer.valueOf(string) or Integer.parseInt(string).
Learning basic programming the the concept of casting will help you tremendously. One datatype can be converted to another using the base classes, which often times deal with String. For instance look at the Documentation of Integer.
Well as you have said that it is a lot of work to change the code and save it as int, I would suggest converting the string into an integer, refer to this link for more information, someone has asked about converting strings to integers, and as Android is Java-based, this can apply to your project:
Converting a string to an integer on Android
Hope this helps.
I FINALLY have the map and points(arrays) working for my app. Quick question: I have a fatal exception with substring(), a "stringIndexOutOfBoundException"
In general, what is that referring to?
An I going past the end of a string using substring()?
Thanks,
testing.substring(1,2);
(I want to parse each character to find specific characters)
I wouldn't use substring() for grabbing 1-length strings (which is just a single character), but rather charAt(int) for specific positions. If you need to go over all characters in the string, you're probably better off with by converting the whole thing to a char[] first (using toCharArray()) and iterate over that.
Yes, you're going past the end of your strings bounds generally.
The Java API even tells you so...
IndexOutOfBoundsException - if beginIndex is negative or larger than the length of this String object.
You should get used to using the API. It tells you what exceptions a method throws and why.
Try printing the Strings length and value before attempting substring. That'll help you see the problem.
For example...
String testing = "Hello StackOverflow";
System.out.println("Length of testing = " + testing.length);
System.out.println("Value of testing = " + testing);
testing.substring(1,2);
Like stated in the official doc here:
public String substring(int beginIndex)
Returns a new string that is a substring of this string. The substring begins with the character at the specified index and extends to the end of this string.
Throws: IndexOutOfBoundsException - if beginIndex is negative or
larger than the length of this String object.
I need calculate a thing. but my formula sentence has occur some problem.
TextView ticketP = (TextView)findViewById (R.id.ticketQ);
ticketP.setText(oneSession.getTicketOder());
String Ctotal = "";
Ctotal = jsonObject.optString("price");
String OneTotal = oneSession.getTicketOder() * Ctotal; // this part has occur the problem which is the operator * .
You'll need to convert the Strings to numeric type before performing any multiplication. Depending on the type of numeric value you are using take a look Double.parseDouble(String string) or Integer.parseInt(String string).
int oneTotal = Integer.valueOf(oneSession.getTicketOder()) * Integer.valueOf(Ctotal);
to convert it again to String use
String.valueOf(oneTotal)
Yes. Your going to have to use the parsing methods in order to convert the string to a native numerical type. You also need to be care about a few things with your code.
json.optString() can return null. opt = optional.
I would suggest using json.getInt() or json.getDouble() this will not only give you the correct type, but also throw an exception if the values aren't correct.
Secondly your going to have to convert your numerical answer back to a string if you want to display it. But this is easy enough with a .toString() or + "" if you are lazy.
So I have a simple Edit-text with number input.
User enters his phone number and it is saved into DB obviously that is the goal.
now every time i do
int contactNumber=Integer.parseInt(mContactNumber.getText().toString());
I get an error thrown saying NumberFormatException for some reason it doesn't like a string of number. I have made sure that mContactNumber field in the android input field has the
android:input="number"
now i also tried just to be sure
int contactNumber=Integer.parseInt(mContactNumber.getText().toString().trim());
still the same error
Guys any ideas?
Try putting the Type to ' long ' instead of ' int '. Hope that will work for you.
This might be because you are leaving the text field empty. Are you sure you are not parsing an empty string?
You need to put a simple condition:
if(mContactNumber.getText().length()>0)
{
int contactNumber=Integer.parseInt(mContactNumber.getText().toString().trim());
}
For phone Number you can not take it as Integer. try to take it as string only and after getting that string you can do the check for the numbers only by
TextUtils.isDigitsOnly(str);