

------------------------------------
代码:
public class PrintTriangle {
    
    public static void main(String[] args) {
        System.out.println("======左边正三角形======");
        printTopLeft(5);
        System.out.println("======左边倒三角形======");
        printDownLeft(5);
        System.out.println("======打印右正三角形======");
        printTopRight(5);
        System.out.println("======打印右倒三角形======");
        printDownRight(5);
        System.out.println("======打印正中三角形======");
        printTopCenter(5);
        System.out.println("======打印倒中三角形======");
        printDownCenter(5);
        System.out.println("======打印中正空三角形======");
        printTopMidBlank(5);
        System.out.println("======打印中倒空三角形======");
        printDownMidBlank(5);
        System.out.println("======打印正人字状======");
        printTopRen(5);
    }
    /**//*
     * 打印正人字状
     */
    public static void printTopRen(int n){
        for(int i = 1; i <= n; i ++){
            for(int j = i; j < n; j ++){
                System.out.print("   ");
            }
            //左半部分
            for(int j = 1; j <= i; j++){
                if(j == 1)
                    System.out.print(" * ");
                else
                    System.out.print("   ");
            }
            //右半部分
            for(int j = 1; j < i; j++){
                if(j == i - 1)
                    System.out.print(" * ");
                else 
                    System.out.print("   ");
            }
            System.out.println();
        }
    }
    /**//*
     * 打印倒空三角形
     */
    public static void printDownMidBlank(int n){
        for(int i = 1; i <= n; i ++){
            for(int j = 1; j < i; j ++){
                System.out.print("   ");
            }
            for(int j = i; j <= n; j ++){
                if(i == 1 || j == i|| i == n)
                    System.out.print(" * ");
                else
                    System.out.print("   ");
            }
            for(int j = i; j < n; j ++){
                if(i == 1 || j == n - 1)
                    System.out.print(" * ");
                else
                    System.out.print("   ");
            }
            System.out.println();
        }
    }
    /**//*
     * 打印中正空三角形
     */
    public static void printTopMidBlank(int n){
        for(int i = 1; i <= n; i ++){
            for(int j = i; j < n; j ++){
                System.out.print("   ");
            }
            //左半部分
            for(int j = 1; j <= i; j++){
                if(j == 1 || i == n)
                    System.out.print(" * ");
                else
                    System.out.print("   ");
            }
            //右半部分
            for(int j = 1; j < i; j++){
                if(j == i - 1 || i == n)
                    System.out.print(" * ");
                else 
                    System.out.print("   ");
            }
            System.out.println();
        }
    }
    /**//*
     * 打印倒中三角形
     */
    public static void printDownCenter(int n){
        for(int i = 1; i <= n; i ++){
            for(int j = 1; j < i; j ++){
                System.out.print("   ");
            }
            for(int j = i; j <= n; j ++){
                System.out.print(" * ");
            }
            for(int j = i; j < n; j ++){
                System.out.print(" * ");
            }
            System.out.println();
        }
    }
    /**//*
     * 打印正中三角形
     */
    public static void printTopCenter(int n){
        for(int i = 1; i <= n; i ++){
            for(int j = i; j < n; j ++){
                System.out.print("   ");
            }
            //左半部分
            for(int j = 1; j <= i; j++){
                System.out.print(" * ");
            }
            //右半部分
            for(int j = 1; j < i; j++){
                System.out.print(" * ");
            }
            System.out.println();
        }
    }
    /**//*
     * 打印右倒三角形
     */
    public static void printDownRight(int n){
        for(int i = n; i >= 1; i --){
            for(int j = n; j > i; j --){
                System.out.print("   ");
            }
            for(int j = i; j >= 1; j --){
                System.out.print(" * ");
            }
            System.out.println();
        }
    }
    /**//*
     * 打印右正三角形
     */
    public static void printTopRight(int n){
        for(int i = 1; i <= n; i ++){
            for(int j = n; j > i; j --){
                System.out.print("   ");
            }
            for(int j = i; j >= 1; j--){
                System.out.print(" * ");
            }
            System.out.println();
        }
    }
    /**//*
     * 打印左正三角型
     */
    public static void printTopLeft(int n){
        for(int i = 1; i <= n; i ++){
            for(int j = 1; j <= i; j ++){
                System.out.print(" * ");
            }
            System.out.println();
        }
    }
    /**//*
     * 打印左倒三角形
     */
   public static void printDownLeft(int n){
       for(int i = 1; i <= n; i ++){
           for(int j = n; j >= i; j --){
                System.out.print(" * ");
            }
            System.out.println();
        }
    }
}