Several simple basic programming questions

Print the integer from 1 to 100, but the number that contains 7 must be skipped,
Each row outputs seven numbers that meet the conditions, separated by spaces. The print format is as follows:

1 2 3 4 5 6 8

Print the number of data that meets the condition

public class Demo {    public static void main(String[] args) {        int count = 1;        for (int i = 1; i <= 100; i++) {            if(i/7==10||i%10==7){                continue;            }else if(count%7==0){                System.out.println(i);                count++;            }else{                System.out.print(i+" ");                count++;            }        }    }}

Print the multiplication table

public class Demo {    public static void main(String[] args) {        for (int i = 1; i <= 9; i++) {            for (int j = 1; j <=i; j++) {                System.out.print(i+"*"+j+"="+(i*j)+" ");            }            System.out.println();        }    }}

1. Define the arraylist set and save it to the following strings: "ABC", "123", "Java", "MySQL", and "Don't run"
2. traverse the set, fill the left side of the element with a length less than 4 with a string of 0, and print out all the elements in the modified set on the console.
Output result format: [0abc, 0123, Java, MySQL, 0 don't run]

Package review; import Java. util. arraylist; import Java. util. arrays;/* idea * defines the arraylist set ---> arraylist <string> xxx = new arraylist <> (); * stores the set ---> XXX. add (data); * traverse the set ---> XXX. fori ---> XXX. get (I) **/public class demo {public static void main (string [] ARGs) {arraylist <string> List = new arraylist <> (); list. add ("ABC"); list. add ("123"); list. add ("Java"); list. add ("MySQL"); list. add ("Don't run"); system. out. print ("["); For (INT I = 0; I <list. size (); I ++) {if (I = List. size ()-1) {system. out. print ("0" + list. get (I) + "]");} else if (list. get (I ). length () <4) {system. out. print ("0" + list. get (I) + ",");} else {system. out. print (list. get (I) + ",");}}}}

Method 2

Package review; import Java. util. arraylist; import Java. util. arrays; public class demo {public static void main (string [] ARGs) {arraylist <string> List = new arraylist <> (); list. add ("ABC"); list. add ("123"); list. add ("Java"); list. add ("MySQL"); list. add ("Don't run"); arraylist <string> list1 = new arraylist <> (); For (INT I = 0; I <list. size (); I ++) {If (list. get (I ). length () <4) {list1.add ("0" + list. get (I);} else {list1.add (list. get (I) ;}} system. out. println (list1 );}}

Several simple basic programming questions