打印菱形

public class TestFor19{
    public static void main(String [] args){
        int size =32;
        int startNum=size/2+1;
        int endNum=size/2+1;
        boolean flag = true;
        for(int j=1;j<=size;j++){
            for(int i=1;i<=size;i++){
                if(i==startNum||i==endNum){//前面为空心菱形，//i>=startNum&&i<=endNum实心菱形
                    System.out.print("*");
                }else{
                    System.out.print(" ");
                }
            
            }
        System.out.println();
        if(endNum==size){
            flag=false;
        }
        if(flag){//flag是true相当于在菱形的上班层
            startNum--;
            endNum++;    
        }else{
            startNum++;
            endNum--;
        }
        
        }
        
    }
    
}