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for(i=1;i=4;i++)
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{
这个小的for是打印每一行前边的空格
for(j=1;j=4-i;j++)
System.out.print(" ");
这个是打印星星的
for(j=1;j=2*i-1;j++)
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=1;i=3;i++)
{
for(j=1;j=i;j++)
System.out.print(" ");
for(j=1;j=7-2*i;j++)
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();
java打印菱形方法：
package circulationDemo;
import java.util.Scanner;
public class Test {
public static void main(String[] args) {
Scanner input = new Scanner(System.in);
System.out.println("请输入要打印的行数：");
int num = input.nextInt();
t1(num);// 正直角
split();
t2(num);// 倒直角
split();
t3(num);// 等腰三角
split();
t4(num);// 等腰倒三角++
split();
t5(num);// 等腰倒三角--
split();
t6(num);// 实心菱形
split();
t7(num);// 空心菱形(1)
split();
t8(num);// 空心菱形(2)
split();
t9(num);// 空心菱形(3)
}
private static void t9(int num) {
for (int k = 1; k = num; k++) {
for (int i = 1; i = (num - k); i++) {
System.out.print(" ");
}
System.out.print("*");
for (int i = 1; i = ((k - 2) * 2 + 1); i++) {
System.out.print(" ");
}
if (k != 1) {
System.out.print("*");
}
System.out.println();
}
for (int k = num-1; k = 1; k--) {
for (int i = 1; i = (num - k); i++) {
System.out.print(" ");
}
System.out.print("*");
for (int i = 1; i = ((k - 2) * 2 + 1); i++) {
System.out.print(" ");
}
if (k != 1) {
System.out.print("*");
}
System.out.println();
}
}
private static void t8(int num) {
// 上半部分
for (int i = 1; i = num; i++) {
// 打印上半部分空格
for (int j = 1; j = num - i; j++) {
System.out.print(" ");
}
// 打印原本实心的*部分
for (int j = 1; j = 2 * i - 1; j++) {
// 仅在一行的开头和末尾打印*
if (j == 1 || j == 2 * i - 1) {
System.out.print("*");
} else {
System.out.print(" ");
}
}
System.out.println();
}
// 下半部分
for (int i = 1; i = num - 1; i++) {
for (int j = 1; j = i; j++) {
System.out.print(" ");
}
for (int j = 1; j = 2 * (num - i - 1) + 1; j++) {
if (j == 1 || j == 2 * (num - i - 1) + 1) {
System.out.print("*");
} else {
System.out.print(" ");
}
}
System.out.println();
}
}
private static void t7(int num) {
// 打印上半部分
for (int i = 1; i = num; i++) {
// 打印空格
for (int j = 1; j = (num - i); j++) {
System.out.print(" ");
}
// 打印*的个数
if (i == 1) {
System.out.print("*");
} else {
System.out.print("*");
// 打印菱形里的空格
for (int j = 1; j = (2 * i - 3); j++) {
System.out.print(" ");
}
System.out.print("*");
}
System.out.println();
}
// 打印下半部分
for (int i = num - 1; i 0; i--) {
// 打印空格
for (int j = 1; j = (num - i); j++) {
System.out.print(" ");
}
// 打印*的个数
if (i == 1) {
System.out.print("*");
} else {
System.out.print("*");
// 打印菱形里的空格
for (int j = 1; j = (2 * i - 3); j++) {
System.out.print(" ");
}
System.out.print("*");
}
System.out.println();
}
}
private static void t6(int num) {
// 上半部分
for (int i = 1; i = num; i++) {
for (int j = 1; j = num - i; j++) {
System.out.print(" ");
}
for (int j = 1; j = 2 * i - 1; j++) {
System.out.print("*");
}
System.out.println();
}
// 下半部分
for (int i = 1; i = num - 1; i++) {
for (int j = 1; j = i; j++) {
System.out.print(" ");
}
for (int j = 1; j = 2 * (num - 1 - i) + 1; j++) {
System.out.print("*");
}
System.out.println();
}
}
private static void t5(int num) {
for (int i = num; i 0; i--) {
for (int j = 1; j = num - i; j++) {
System.out.print(" ");
}
for (int j = 1; j = 2 * i - 1; j++) {
System.out.print("*");
}
System.out.println();
}
回答于 2022-12-14
Java利用for循环输出空心菱形的实例代码
编写程序，在控制台上输出空心菱形，对角距离为6.
代码如下：
public class Diamond {
public static void main(String[] args) {
printHollowRhombus(6);
}
public static void printHollowRhombus(int size) {
if (size % 2 == 0) {
size++;// 计算菱形大小
}
for (int i = 0; i size / 2 + 1; i++) {
for (int j = size / 2 + 1; j i + 1; j--) {
System.out.print(" ");// 输出左上角位置的空白
}
for (int j = 0; j 2 * i + 1; j++) {
if (j == 0 || j == 2 * i) {
System.out.print("* ");// 输出菱形上半部边缘
} else {
System.out.print(" ");// 输出菱形上半部空心
}
}
System.out.println(""); //换行
}
for (int i = size / 2 + 1; i size; i++) {
for (int j = 0; j i - size / 2; j++) {
System.out.print(" ");// 输出菱形左下角空白
}
for (int j = 0; j 2 * size - 1 - 2 * i; j++) {
if (j == 0 || j == 2 * (size - i - 1)) {
System.out.print("* ");// 输出菱形下半部边缘
} else {
System.out.print(" ");// 输出菱形下半部空心
}
}
System.out.println(""); //换行
}
}
}
效果如图：