public static void main (String args[]){

      int TotalLayer=9 

      for(int layer=1 layer<=TotalLayer layer++) {

         for(int space=1 space<=Math.abs((TotalLayer+1)/2-layer) space++){

            System.out.print(" ")

         }

         for(int b=1 b<=TotalLayer-2*Math.abs((TotalLayer+1)/2-layer) b++){

            System.out.print("*")

         }

         System.out.println()

      }

   }

}

用3个for循环打出菱形，可以改变TotalLayer的值来改变菱形的大小

第一个for循环规定多少行

第二个for循环规定每行有多少个空格

第三个for循环规定每行有多少个星号

然后换行，重复2,3循环直到完成第一个循环

最后菱形完成

for(i=1i<=4i++)

{

这个小的for是打印每一行前边的空格

for(j=1j<=4-ij++)

System.out.print(" ")

这个是打印星星的

for(j=1j<=2*i-1j++)

System.out.print("*")

这个是打印完一行的换行

System.out.println("")

}

下边的是一样的  只不过每一行的空格和星星数   和上边是翻过来的

for(i=1i<=3i++)

{

for(j=1j<=ij++)

System.out.print(" ")

for(j=1j<=7-2*ij++)

System.out.print("*")

System.out.println("")

}

java.sql.SQLException: 无效的列索引

无效的列索引

at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:111)

at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:145)

at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:207)

atoracle.jdbc.driver.OraclePreparedStatement.setStringInternal(OraclePreparedStatement.java:5328)

atoracle.jdbc.driver.OraclePreparedStatement.setString(OraclePreparedStatement.java:5320)

at untitled5.addreader1.validID(addreader1.java:128)

at untitled5.addreader1.jButton1_actionPerformed(addreader1.java:97)

at untitled5.addreader1_jButton1_actionAdapter.actionPerformed(addreader1.java:175)

at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)

at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)

at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)

at javax.swing.DefaultButtonModel.setPressed(Unknown Source)

at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)

at java.awt.Component.processMouseEvent(Unknown Source)

at javax.swing.JComponent.processMouseEvent(Unknown Source)

at java.awt.Component.processEvent(Unknown Source)

at java.awt.Container.processEvent(Unknown Source)

at java.awt.Component.dispatchEventImpl(Unknown Source)

at java.awt.Container.dispatchEventImpl(Unknown Source)

at java.awt.Component.dispatchEvent(Unknown Source)

at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)

at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source

at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)

at java.awt.Container.dispatchEventImpl(Unknown Source)

at java.awt.Window.dispatchEventImpl(Unknown Source)

at java.awt.Component.dispatchEvent(Unknown Source)

at java.awt.EventQueue.dispatchEvent(Unknown Source)

at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)

at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)

at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)

at java.awt.EventDispatchThread.pumpEvents(Unknown Source)

at java.awt.EventDispatchThread.pumpEvents(Unknown Source)

at java.awt.EventDispatchThread.run(Unknown Source)

代码：String driverName = "oracle.jdbc.OracleDriver"

Driver driver = (Driver) Class.forName(driverName).newInstance()

//连接数据库

Connection con = DriverManager.getConnection(

"jdbc:oracle:thin:@LONG:1521:orcl", "sysman", "tongfang")

PreparedStatement pstmt = con.prepareStatement(

" insert into reader values(?)")

pstmt.setString(1, str1)

pstmt.setString(2,str2)

pstmt.setString(3,str3)

pstmt.setString(4,str4)

ResultSet res = pstmt.executeQuery()

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

package demo

public class Demo01 {

public static void main(String[] args) {

int i, j, k

for (i = 1i <= 5i++) {

for (j = 1j <= 5 - ij++)

System.out.print(" ")

for (k = 1k <= 2 * i - 1k++)

System.out.print("*")

System.out.println("")

}

for (i = 1i <= 4i++) {

for (j = 1j <= ij++)

System.out.print(" ")

for (k = 1k <= 9 - 2 * ik++)

System.out.print("*")

System.out.println("")

}

}

}

绘制算法：

1、分为两部分，上半部分和下半部分

2、输出空格部分换个输出*部分

3、最后一个标签需要换行