求面向对象的笔记和总结 ,   各位大神帮帮忙

int i, j;
for (i = 1; i <= 4; i++) {
for (j = 1; j <= 4 - i; j++)
System.out.print(" ");
for (j = 1; j <= 2 * i - 1; j++)
System.out.print("*");
System.out.println();