利用程序输出如下图形

利用程序输出如下图形:
*
***
*****
*******
*****
***
*

public class day4_4{
public static void main(String[] args ){
int i = 1,j,k = 1;
while(i <= 4){
j = 1;
while(j < 2*i){
System.out.print("* ");
j++;
}
i++;
System.out.println();
}
j = 2*(i-1);
while(i>4 && i <= 7){
k = 1;
while(k < j-(i-4)*2){
System.out.print("* ");
k++;
}
i++;
System.out.println();
}
}
}

public class Example4 {

/**
*利用程序输出如下图形:
*
* *
* **
* ****
* ******
* ****
* **
* *
*/
public static void main(String[] args) {

int sum = 5; //一半的大小

for (int i = 1; i <= sum; i++) { //行数循环
for (int j = 1; j <= i * 2 - 1; j++) { //星号个数循环
System.out.print("*");
}
System.out.println();
}

for (int i = sum - 1; i > 0; i--) {//行数循环
for (int j = 1; j <= i * 2 - 1; j++) {//星号个数循环
System.out.print("*");
}
System.out.println();
}

}

}