Question

java中用for循环怎样打印三角行啊，主要是不理解什么情况外层循环递增什么时候递减，如等腰三角形

java中用for循环怎样打印三角行啊，主要是不理解什么情况外层循环递增什么时候递减，如等腰三角形外层循环递增，而倒直角三角形外层循环递减，原理是什么啊，求解啊？

Answer 1

public class Test1
{
public static void main(String[] params)
{
String str = sanjiao(11);
System.out.println(str);
String str2 = sijiao(11);
System.out.println(str2);
}

public static String sijiao(int num)
{
StringBuffer sb = new StringBuffer();
for (int i = 1; i <= num; i++)
{
if (i == 1 || i == num)
{
String str = numStr("*", num);
sb.append(str + "\n");
}
else if (i % 2 == 0)
{

}
else if (i % 2 == 1)
{
String str = middlePad("*", ' ', num - 2);
sb.append(str + "\n");
}
}
return sb.toString();
}

public static String sanjiao(int num)
{
StringBuffer sb = new StringBuffer();
for (int i = 1; i <= num; i++)
{
if (i == num)
{
String str = numStr("*", num);
sb.append(str + "\n");
}
else if (i == 1)
{
int j = (num - i)/2;
String str = leftPad("*", ' ', j);
str = rightPad(str, ' ', j);
sb.append(str + "\n");
}
else if (i % 2 == 0)
{

}
else if (i % 2 == 1)
{
int j = (num - i)/2;
String str = middlePad("*", ' ', i - 2);
str = leftPad(str, ' ', j);
str = rightPad(str, ' ', j);
sb.append(str + "\n");
}
}
return sb.toString();
}

public static String numStr(String str, int num)
{
StringBuffer sb = new StringBuffer();
for (int i = 0; i < num; i++)
{
sb.append(str);
}
return sb.toString();
}

public static String leftPad(String str, char c, int num)
{
StringBuffer sb = new StringBuffer();
for (int i = 0; i < num; i++)
{
sb.append(c);
}
sb.append(str);
return sb.toString();
}

public static String rightPad(String str, char c, int num)
{
StringBuffer sb = new StringBuffer();
sb.append(str);
for (int i = 0; i < num; i++)
{
sb.append(c);
}
return sb.toString();
}

public static String middlePad(String str, char c, int num)
{
StringBuffer sb = new StringBuffer();
sb.append(str);
for (int i = 0; i < num; i++)
{
sb.append(c);
}
sb.append(str);
return sb.toString();

}

}

Answer 2

for(int i=1;i<败伏=7;i=i+2)
{

for(int k=1;k<=(7-i)/2;k++)
{
System.out.print(" "轿液);
}
for(int j=1;j<察帆携=i;j++)
{
System.out.print("*");
}
System.out.println();
}