Introduction to String Indexing
String Indexing
Each character of a String literal has an associated index, or label, with the first character being index 0 and each subsequent index is one more than the last. Consider the following example.
- The index of
D is 0.
- The index of
u is 1.
- The index of
k is 2.
- The index of
e is 3.
char charAt(int index)
This method returns the char value at the specified index.
Your Turn
Let's try it in the Java Playground.
- add a statement to use
charAt to access the last character of phrase and assign it to a variable named last.
start is assigned D since that is the character at index 0.middle is assigned v since that is the 8th character in phrase or the character at index 7.
int indexOf(String str)
This method returns
- the index within this string of the first occurrence of the parameter
str.
- -1 if this word does not contain an occurrence of
str.
Your Turn
Let's try it in the Java Playground.
- Predict the values of
index1, index2, and index3.
- Run the code to see if your predictions are correct.
index1 is assigned the value 7. Starting with A being at index 0, the n in ness is at index 7. index2 is assigned the value 3. Starting with A being at index 0, the s in some is at index 3.index3 is assigned teh value -1. This method distinguishes between upper and lowercase letters, so Awesome and awesome are considered different values. As such, awesome does not appear in word.
There are multiple indexOf methods that take different parameters, some specifying the range of indexes where str is being searched.
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