java编程 计算8+88+888+8888+...

用for循环计算8+88+888+8888+...的前10项的和 请给出步骤 谢谢！

public class Test{
public static void main(String[] args)
{
String strNum = "";
int result =0;
for(int i=0;i<8;i++){
strNum+="8";
result+=Integer.parseInt(strNum);
}
System.out.println("8+88+888+8888...的结果为："+result);


}
}

int sum=0; int m=8 for(int i=0;i<10;i++){ sum=sum+m; m=m*10+8; }

public class test { public static void main(String [] args) { long a = 8, b = 8; long s = 8; String str = "8"; for ( int i = 1; i < 10; ++i ) { s += a; a = a * 10 + b; str += "+" + String.valueOf( a ); } System.out.println( str + "=\n" + s ); } }