How to Directly Output Arrays, Traverse Strings, and Read Keyboard Input in Java

1. Directly Output an Array

int[] arr = {1, 2, 432, 32, 54, 32, 3, 7, 657};
System.out.println(Arrays.toString(arr));
// Output: [1, 2, 432, 32, 54, 32, 3, 7, 657]

2. Two Approaches to Traverse a String

(a) Convert the string to a char array and iterate

Use toCharArray to obtain a character array, then use an enhanced for‑loop to print each character.

String str = "fje你kw我FDQFj你feAF他Eajf他eo2FA我FEjfew";
char[] str2 = str.toCharArray();
for (char c : str2) {
    System.out.println(c);
}

(b) Access characters directly with charAt()

Iterate over the string indices and call charAt(i) to get each character.

String str = "fje你kw我FDQFj你feAF他Eajf他eo2FA我FEjfew";
for (int i = 0; i < str.length(); i++) {
    System.out.println(str.charAt(i));
}

3. Reading Input from the Keyboard

Scanner sc = new Scanner(System.in);
String s = sc.next();          // reads a token separated by whitespace
String line = sc.nextLine();   // reads the rest of the line
int num = sc.nextInt();        // reads an integer

Note: Methods like next() and nextInt() do not consume the line‑break character, while nextLine() does. After calling next() or nextInt(), a subsequent nextLine() may return an empty line. Call an extra nextLine() to consume the leftover newline before reading the intended line.