java for语法

package ne;
 
import java.util.List;
import java.util.stream.Stream;
 
public class c3 {
    public static void main(String[] args) {
        for (int i = 1; i <= 15; i++) {
            System.out.printf("%03d\t", i);
            System.out.println();
            for (int ix = 15; ix >= 1; ix -= 2) {
                System.out.printf("%03d\t", ix);
            }
//计算1+2+3+...+100 = ?
            int sum = 0;
            for (int iv = 1; iv <= 100; iv++) {
                sum = sum + iv;
            }
            System.out.println("\n1+2+3+...+100=" + sum);
        }
 
        System.out.printf("===============================\n");
        /*
        for (;;) {
        System.out.println("aaa");
        }
        */
        for (int i = 3; i <= 13; i++) {
            System.out.printf("%02d ", i);
        }
        System.out.println();
        for (int i = 3; i <= 13; i++) {
            if (i % 2 != 0) {
                System.out.printf("%02d ", i);
            }
        }
        System.out.println();
        for (int i = 1; i < 20; i++) {
            if (i % 2 != 0) {
                System.out.printf("%d ", i);
            }
        }
 
        System.out.printf("===============================\n");
        for (int i = 1; i < 7; i++) {
            System.out.printf("%d ", i);
        }
        System.out.println();
        for (int i = 6; i >= 1; i--) {
            System.out.printf("%d ", i);
        }
 
        System.out.printf("===============================\n");
        int num = 15;
        for (int i = 1; i < 15; i += 2) {
//String str = " ".repeat(num--) + "*".repeat(i);
//System.out.println(str);
            for (int n = --num; n >= 0; n--) {
                System.out.print(" ");
            }
            for (int j = 1; j <= i; j++) {
                System.out.print("*");
            }
            System.out.println();
        }
 
 
        System.out.printf("===============================\n");
//        for in（javascript)
//        foreach(方法，不能使用continue和break)
//        for of （javascript)
        //forin  foreachforof循环集合数组
        int[] nums = {10, 20, 30};
        //toList()java16增加的方法
        for (int i : Stream.of(1, 2, 3, 4, 5, 6).toList()) {
            System.out.println(i);
        }
 
        //List.of()接口方法是java9新增方法
        for (int i : List.of(10, 20, 30)) {
            System.out.println(i);
        }
 
        for (int i : Stream.of(11, 22, 33).toList()) {
            System.out.println(i);
        }
 
        for (int am : nums) {
            System.out.println(am);
            break;
        }
 
        for (String s : new String[]{"java", "php", "python"}) {
            System.out.println(s);
        }
 
        for (char c : "javascript".toCharArray()) {
            System.out.println(c);
        }
 
        System.out.println("--------------------------------");
        for (String value : System.getenv().values()) {
            System.out.println(value);
        }
        System.out.printf("===============================\n");
        System.out.printf("===============================\n");
        System.out.printf("===============================\n");
 
 
    }
 
}