Develop Reference

GetText compare

So i have a EditText field, which i want to, check if the age is above and under my limits.
if (Integer.parseInt(age.getText().toString()) < 18 && Integer.parseInt(age.getText().toString()) >= 0)
But also, i want to simply check if the field is empty, for what i used.
else if (age.getText().toString().isEmpty())
Unluckly this one is not working, i think it sort of get in to conflict with the first one or something, because i tried with just one condition of both, and it works..
I also tried to store in String variable the method to check isEmpty(), and also in int one, to do the age comparation, but it still not working.
Thanks in advance.

The code should be:
if (age.getText().toString().trim().isEmpty()){
//The EditText field is empty
}else{
try{
if (Integer.parseInt(age.getText().toString().trim()) < 18 && Integer.parseInt(age.getText().toString().trim()) >= 0){
//Your code here
}else{
//Input value is over 18 or under 0
}
}catch(Exception ex){
//There was an error parsing the input (if your user writes letters, parseInt fails)
}
}

Java (Android) - can't detect first character of string?

Not sure if I've missed something really obvious. I know for sure that my String is as follows:
1This is a test message
I'm trying to detect whether the first character is '1', so here's some of my code:
//This outputs '1'
Toast noCmd = Toast.makeText(Play.this, decodedMessage.substring(0,1), Toast.LENGTH_SHORT);
noCmd.show();
if (decodedMessage.charAt(0) == 1) {
noCmd = Toast.makeText(Play.this, "This should show up", Toast.LENGTH_SHORT);
noCmd.show();
noCmd = Toast.makeText(Play.this, finalMessage + " from " + sender, Toast.LENGTH_SHORT);
noCmd.show();
}
if (decodedMessage.substring(0,1) == "1") {
noCmd = Toast.makeText(Play.this, "This should show up", Toast.LENGTH_SHORT);
noCmd.show();
noCmd = Toast.makeText(Play.this, finalMessage + " from " + sender, Toast.LENGTH_SHORT);
noCmd.show();
}
As you can see, I'm trying two methods to get the toasts inside the if statement to show up. Weirdly, when the code is run, only the top (unconditional) toast displays.
Any ideas?

For the first one, the char is '1'. What's currently happening in your code is that because you're comparing a char with an integer, the char is being converted to an int using its character code. For a 1, that comes out as 49, which is not equal to the integer 1. You need to compare the char you're retrieving from the String with the char representing a digit "1", and that means you need to write it as '1'.
For the second one, you need to use .equals() to test for String equality, rather than ==. If you take two String objects s and t that have the same content, then you still will find that s==t will come out as false, unless they happen to be pointing at the same bit of memory (i.e., they're the same instance). To check whether they have the same content, you check
s.equals(t)
rather than
s==t
So, in summary, make the first one
if (decodedMessage.charAt(0) == '1') {
//toast stuff
}
and the second one
if ("1".equals(decodedMessage.substring(0,1))) {
//toast stuff
}
The reason, by the way, for not writing
if (decodedMessage.substring(0,1).equals("1")) {
//toast stuff
}
instead is that if the String on which you call .equals() is null then you'll end up with a NullPointerException, which usually you want to avoid. Actually in this case it would be fine, because the substring() call won't return null, but in the general case if you want to test whether s and "something" are equal then you use
"something".equals(s)
rather than
s.equals("something")
just in case s is null.

1 is an integer with value 1. If you want the ASCII 1, use '1' in single quotes which has the integer value of 49.
For comparing strings, use equals() and not ==. See How do I compare strings in Java?

To compare strings you need to use equals method:
if("1".equals(decodedMessage.charAt(0))){
}

Most efficient way of comparing long arrays of strings

I'm using the speech recognizer to get a voice input from the user, it returns an array of 5 strings which I pass to this method
public int analyzeTag(ArrayList<String> voiceResults,Editor editor, Context context){
for (String match : voiceResults) {
Log.d(TAG, match);
if (match.equalsIgnoreCase(context.getResources().getString(R.string.first_tag))){
editor.append(context.getResources().getString(R.string.first_tag));
return 1;
}
else if (match.equalsIgnoreCase(context.getResources().getString(R.string.second_tag))){
editor.append(context.getResources().getString(R.string.second_tag));
return 1;
}
//etc....(huge list of tags)
//Some tags might also have acceptable variations, example:
else if (match.equalsIgnoreCase("img") || match.equalsIgnoreCase("image")
{
editor.append("img"); //the string to append is always taken from the first variation
}
}
return 0;
}
This method compares the results with a list of tags, the tag list will be pretty big with hundreds of tags so I would like to find the most efficient way to do this operation.
I need help with:
1.Is my way of comparing results the most efficient? Is there a better way? (from the user experience perspective, I don't want users waiting a long time to get a result).
The voice input will be a big part of my app so this method will be called quite often
2.I have a long list of tags, obviously the if(), elseIf() route is gonna be quite repetitive, is there a way to iterate this? Considering the fact that some tags might have variations (even more than 1)and that the variation 1 ("img") will be the same for everyone, but other variations will be locale/language sensitive example: "image" for english users "immagini" for italian users etc.
Text appended to the editor will be always taken from the first variation

How about puting tags in a StringArray and then iterate though the array ?
String[] tags = context.getResources().getStringArray(R.array.tags);
for (String match : voiceResults) {
for (int index = 0; index < tags.length; index++ ) {
if (match.equalsIgnoreCase(tags[index]) {
editor.append(tags[index]);
}
}
}
Here's the doc on StringArray

Only else part is executed [duplicate]

This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
How do I compare strings in Java?
even whel length is 0 and flag9 is null only else part is executed.can someone help me
Log.d(TAG, "flag8 "+ getIntent().getExtras().getString("flag").length());
Log.d(TAG, "flag9 "+ getIntent().getExtras().getString("flag"));
if( getIntent().getExtras().getString("flag")=="0" ||getIntent().getExtras().getString("flag").length()==0)
{
Log.d(TAG, "hidebeta "+ getIntent().getExtras().getString("flag"));
beta.putExtra("beta", "hidebeta");
flag=1;
beta.putExtra("flag", "1");
}
else {
beta.putExtra("beta","showbeta");
Log.d(TAG, "showbeta "+ getIntent().getExtras().getString("flag"));
flag=0;
beta.putExtra("flag","0");
}

In Java you cannot use == to compare Strings, you must use:
if(string.equals("example"))
So let's use equals() in your conditional and optimize it:
String flag = getIntent().getStringExtra("flag");
if(flag.equals("0") || flag.length()==0)
(Also you ought to be safe and check if getIntent() and flag are not null before trying to access them.)
Read How do I compare strings in Java? or the documentation on Comparing Strings for more information.

use equals to compare strings, not == (which compares references to objects)

You should never use == operator for comparing two Strings, as it compares the actual references, not their values. Use equals() method instead. Hope this helps.

IfElse or regex

Which one of these would be the best way to do this when you have very long IfElse?
if (text.contains("text"))
{
// do the thing
}
else if (text.contains("foo"))
{
// do the thing
}
else if (text.contains("bar"))
{
// do the thing
}else ...
Or
if (text.contains("text") || text.contains("foo") || ...)
{
// do the thing
}
Or maybe
Pattern pattern = Pattern.compile("(text)|(foo)|(bar)|...");
Matcher matcher = pattern.matcher(text);
if(matcher.find())
{
// do the thing
}
And I mean ONLY when you have to check a lot of these. Thanks!

I would personally use a set as I think it is easier to read and the contains will be efficient in O(1):
Set<String> keywords = new HashSet<String>();
keywords.add("text");
keywords.add("foo");
keywords.add("bar");
if(keywords.contains(text)) {
//do your thing
}
And if you like it compact, you can also write:
Set<String> keywords = new HashSet<String>(Arrays.asList("text", "foo", "bar"));
if(keywords.contains(text)) {
//do your thing
}
And finally, if you always use the same list, you can make keywords private static final instead of recreating it each time you run the method.
EDIT
Following a comment, it is true that what is above is equivalent to using a condition with text.equals("xxx"), not text.contains("xxx"). If you really meant to use contains, then you would have to iterate over the set and test each string, but it becomes an O(n) operation:
for (String key : keywords) {
if (text.contains(key)) {
//do your stuff
break;
}
}

Usually long If else statements are replaced with case statements, but this is not always possible. If I where to recommend, I would go for the second option, option 1 will give you a bunch of If else if else statements which do the same thing while for the third case, regular expressions tend to grow pretty large pretty fast.
Again depending on how much alot is, it could eventually be better to just throw all your strings in a data structure and iterate over it to see if the element is in it.

String[] storage = {
"text",
"foo",
"bar",
"more text"
};
for(int i=0; i < storage.length(); i++){
//Do Something
}
Does this help?