What is substring in AP® Computer Science A?

substring

String methods substring(from, to), which returns the characters from index from to to - 1, and substring(from), which goes to the end.

Appears in the course and exam description (CED): 1.15.B.21.15.B.3

The number of characters returned is to - from. substring(i, i + 1) gives the single character at index i.

String word = "INTERFACE";
System.out.println(word.substring(0, 5));
System.out.println(word.substring(5));
System.out.println(word.substring(2, 3));

Output:

INTER
FACE
T