JavaBasic syntax and simple programsStrings

Processing strings

Strings and arrays

In some sense, a string looks like an array of characters.

It's possible to convert between strings and character arrays using special methods:

char[] chars = { 'A', 'B', 'C', 'D', 'E', 'F' };

String stringFromChars = String.valueOf(chars); // "ABCDEF"

char[] charsFromString = stringFromChars.toCharArray(); // { 'A', 'B', 'C', 'D', 'E', 'F' }

String theSameString = new String(stringFromChars); // "ABCDEF"

A string can be separated by delimiters to an array of strings. To perform this, call the method split passing a string for splitting.

String text = "a long text";
String[] parts = text.split(" "); // [a, long, text]

Iterating over a string

It's possible to iterate over characters of a string using a loop (while, do-while, for-loop).

See the following example.
String scientistName = "Isaac Newton";

for (int i = 0; i < scientistName.length(); i++) {
    System.out.print(scientistName.charAt(i) + " "); // print the current character
}

The code outputs:

I s a a c   N e w t o n

If you'd like to use the for-each loop, first you should convert a string to an array of characters and iterate it.


String str = "strings are not primitive types!";

int count = 0;
for (char ch : str.toCharArray()) {
    if (Character.isWhitespace(ch)) {
        count++;
    }
}


System.out.println(count); // 4

The code above counts and prints the number of spaces in str. The result is 4.
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