How to convert a string to an int array in Java __java learning

How to convert a string to an array of int: three ways to provide
Import Java.util.Arrays;
public class strtointarr{
public static void Main (string[] args) {
String str = "1234567";
int[] demo01 = demo01 (str);
int[] demo02 = demo02 (str);
int[] demo03 = demo03 (str);
System.out.println (arrays.tostring (demo01));
System.out.println (arrays.tostring (demo02));
System.out.println (arrays.tostring (demo03));
DEMO04 (str);
}
Substring method using the parseint and string classes of the integer class (direct conversion method)
private static int[] demo01 (String str) {
int[] arr = new int[str.length ()];
for (int i=0; i<str.length (); i++) {
Arr[i] = Integer.parseint (str.substring (i,i+1));
}
return arr;
}
Using the Charat method of the string class and the Getnumricvalue method of the character class (indirect conversion method)
private static int[] demo02 (String str) {
int[] arr = new int[str.length ()];
for (int i=0; i<str.length (); i++) {
Arr[i] = Character.getnumericvalue (Str.charat (i));
}
return arr;
}
Another kind of indirect conversion method, ToCharArray method of String class
private static int[] demo03 (String str) {
char[] arr = new char[str.length ()];
int[] arr2 = new int[str.length ()];
arr = Str.tochararray ();
for (int i=0; i<str.length (); i++) {
Arr2[i] = arr[i]-48;//number 0~9 ASCII code is 48~57
}
return arr2;
}
Test the array length transformation in the process of string-turn character array to int array
private static void demo04 (String str) {
char[] arr = new char[str.length ()];
int[] arr2 = new int[str.length ()];
arr = Str.tochararray ();
for (int i=0; i<str.length (); i++) {
Arr2[i] = Arr[i];
}
System.out.println ("String length:" + str.length ());
System.out.println ("character array length:" + arr.length);
SYSTEM.OUT.PRINTLN ("int array length:" + arr.length);
}
}