1.打印等腰三角形
import java.util.Scanner;//引入Scanner包，用于输入值public class HomeWork01 {public static void main(String[] args) {Scanner sc=new Scanner(System.in);System.out.println("请输入打印的等腰三角形的行数:");int line=sc.nextInt();for (int i = 0; i < line; i++) {//控制打印的行数for (int j = 1; j <line-i; j++) {System.out.print(" ");//打印空格}for (int k= 0; k<=i ; k++) {System.out.print("* ");//打印*加空格}System.out.println();//换行}}}
输入需要打印的行数n，即可打印出n行的等腰三角形
2. 打印菱形
import java.util.Scanner;public class HomeWork02 {public static void main(String[] args) {Scanner sc = new Scanner(System.in);System.out.println("请输出打印菱形的边长：");int bian = sc.nextInt();for (int i = 0; i < bian; i++) {for (int j = 1; j < bian - i; j++) {System.out.print(" ");}for (int k = 0; k <= i; k++) {System.out.print("* ");}System.out.println();}for (int i = 0; i < bian; i++) {for (int j = 0; j <= i; j++) {System.out.print(" ");}for (int k = 1; k < bian - i; k++) {System.out.print("* ");}System.out.println();}}}
//打印菱形的方法和打印等腰三角形的方法如出一辙，只不过是到了n行的时候继续打印n+1行，然后打印*的个数减一。
输入要打印菱形的边数n，这里演示n=10；运行结果如下：
3.打印平行四边形
import java.util.Scanner;public class HomeWork03 {public static void main(String[] args) {Scanner sc = new Scanner(System.in);System.out.println("请输出打印平行四边形的边长：");int line = sc.nextInt();for (int i = 0; i < line; i++) {for (int j = 0; j <line-i ; j++) {System.out.print(" ");}for (int k = 0; k < line; k++) {System.out.print("* ");}System.out.println();}}}
输入需要打印的平行四边形行数n，这里演示n=8；
有更多简单好的方法，小伙伴可以在下边评论哦！！！！！
