(1)变量计算两个数的和
import javax.swing.*;
public class LianXi
{
public static void main(String[] args)
{
int a, b,sum;
a =10;
b = 30;
sum = a+b;
JOptionPane.showMessageDialog(null, "a+b = "+sum);
System.exit(0);
}
}
(2)输入一个数字N,输出1~N中7的倍数,以及数字中7的个数,
import java.util.*;
public class StringTest {
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner c = new Scanner(System.in);
System.out.println("请输入一个数字N:");
int N = c.nextInt();
int count = 0;
for(int i = 1;i<=N;i++)
{ String n = String.valueOf(i);
if(i%7==0||n.contains("7"))
{
System.out.println(i);
count++;
}
}
System.out.println("一共"+count+"个");
}
}