Extract substring from a string

what is the best 开发者_JAVA百科way to extract a substring from a string in android?

If you know the Start and End index, you can use

String substr=mysourcestring.substring(startIndex,endIndex);

If you want to get substring from specific index till end you can use :

String substr=mysourcestring.substring(startIndex);

If you want to get substring from specific character till end you can use :

String substr=mysourcestring.substring(mysourcestring.indexOf("characterValue"));

If you want to get substring from after a specific character, add that number to .indexOf(char):

String substr=mysourcestring.substring(mysourcestring.indexOf("characterValue") + 1);

substring():

str.substring(startIndex, endIndex); 

Here is a real world example:

String hallostring = "hallo";
String asubstring = hallostring.substring(0, 1); 

In the example asubstring would return: h

There is another way , if you want to get sub string before and after a character

String s ="123dance456";
String[] split = s.split("dance");
String firstSubString = split[0];
String secondSubString = split[1];

check this post- how to find before and after sub-string in a string

substring(int startIndex, int endIndex)

If you don't specify endIndex, the method will return all the characters from startIndex.

startIndex : starting index is inclusive

endIndex : ending index is exclusive

Example:

String str = "abcdefgh"

str.substring(0, 4) => abcd

str.substring(4, 6) => ef

str.substring(6) => gh

you can use this code

    public static String getSubString(String mainString, String lastString, String startString) {
    String endString = "";
    int endIndex = mainString.indexOf(lastString);
    int startIndex = mainString.indexOf(startString);
    Log.d("message", "" + mainString.substring(startIndex, endIndex));
    endString = mainString.substring(startIndex, endIndex);
    return endString;
}

in this mainString is a Super string.like "I_AmANDROID.Devloper" and lastString is a string like"." and startString is like"_". so this function returns "AmANDROID". enjoy your code time.:)

use text untold class from android:
TextUtils.substring (charsequence source, int start, int end)

You can use subSequence , it's same as substr in C

 Str.subSequence(int Start , int End)

When finding multiple occurrences of a substring matching a pattern

    String input_string = "foo/adsfasdf/adf/bar/erqwer/";
    String regex = "(foo/|bar/)"; // Matches 'foo/' and 'bar/'

    Pattern pattern = Pattern.compile(regex);
    Matcher matcher = pattern.matcher(input_string);

    while(matcher.find()) {
      String str_matched = input_string.substring(matcher.start(), matcher.end());
        // Do something with a match found
    }

The best way to get substring in Android is using (as @user2503849 said) TextUtlis.substring(CharSequence, int, int) method. I can explain why. If you will take a look at the String.substring(int, int) method from android.jar (newest API 22), you will see:

public String substring(int start) {
    if (start == 0) {
        return this;
    }
    if (start >= 0 && start <= count) {
        return new String(offset + start, count - start, value);
    }
    throw indexAndLength(start);
}

Ok, than... How do you think the private constructor String(int, int, char[]) looks like?

String(int offset, int charCount, char[] chars) {
    this.value = chars;
    this.offset = offset;
    this.count = charCount;
}

As we can see it keeps reference to the "old" value char[] array. So, the GC can not free it.

In the newest Java it was fixed:

String(int offset, int charCount, char[] chars) {
    this.value = Arrays.copyOfRange(chars, offset, offset + charCount);
    this.offset = offset;
    this.count = charCount;
}

Arrays.copyOfRange(...) uses native array copying inside.

That's it :)

Best regards!

All of The responders gave good answers. However, I am giving you all relatable methods for this so that any one can get from one place, I'll edit my answer if I find something new.

1. substring(0)- use for cut string from given specific char.

2. Substring(0,2)- give you sub string from starting(0) and ending(2) characters.

3. Split("NAME")- return you string in two parts first is that you use in split "NAME" and another part is rest of string combine.

4. subSequence(0,3) - returns sequence of give start(0) and ending index(3).

   This one is not specifically use for split string but though it may be use full for some one

5. startswith("A",3)- returns string for specific starting character.

   For example:

   String s = "StackOverflow";
   String[] split = s.split("Stack");
   
   System.out.println("STRING NAME:"+s.substring(2));
   System.out.println("STRING NAME:"+s.substring(2,3));
   System.out.println("STRING NAME:"+split[1]);
   System.out.println("STRING NAME:"+split[0]);
   System.out.println("STRING NAME:"+s.subSequence(2,5));
   

   Output:

    1)ackOverflow
    2)a
    3)Overflow
    4)stack
    5)ack
   

I hope this will give you enough information that you require.