Range Over Built in Java

Here we use range to sum the numbers in a slice. Arrays work like this too.

import java.util.Arrays;
import java.util.List;

public class RangeExample {
    public static void main(String[] args) {
        List<Integer> nums = Arrays.asList(2, 3, 4);
        int sum = 0;
        for (int num : nums) {
            sum += num;
        }
        System.out.println("sum: " + sum);

        for (int i = 0; i < nums.size(); i++) {
            if (nums.get(i) == 3) {
                System.out.println("index: " + i);
            }
        }
        
        java.util.Map<String, String> kvs = java.util.Map.of("a", "apple", "b", "banana");
        for (java.util.Map.Entry<String, String> entry : kvs.entrySet()) {
            System.out.println(entry.getKey() + " -> " + entry.getValue());
        }

        for (String k : kvs.keySet()) {
            System.out.println("key: " + k);
        }

        String str = "go";
        for (int i = 0; i < str.length(); i++) {
            System.out.println(i + " " + (int) str.charAt(i));
        }
    }
}

To run the program, compile the code into a .class file and then use java to execute it.

$ javac RangeExample.java
$ java RangeExample
sum: 9
index: 1
a -> apple
b -> banana
key: a
key: b
0 103
1 111

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Range Over Built in Java