问题

我在编程世界和 Java 世界都是新手。
我正在尝试学习使用 for 循环并用它来解决图案问题。

我想使用 for 循环绘制以下图案：

    *
    **
    ***
    ****
    *****

我正在使用以下代码来实现：

```java
public class PatterWithForLoop {

    public static void main(String args[]){
        for(int i = 0; i <= 5; i++){
            System.out.println("*" + "\n");
        }
    }
}

但是，我只得到了在 15 行中都是 *，而不是图案。
请问有谁能帮忙解决这个问题吗？

提前谢谢。

<details>
<summary>英文:</summary>

I am very new in the programming world and in Javaland too. 
I am trying to learn for loop and solving pattern with it. 

I want to draw this pattern using for loop : 

    *
    **
    ***
    ****
    *****

I am using this code to achieve this:

public class PatterWithForLoop {

public static void main(String args[]){
    for(int i = 0; i <= 5; i++){
        System.out.println("*" + "\n");
    }
}

}

But, I am only getting * in 15 lines, not in the pattern. 
Please, anyone can help to solve this issue here? 

Thanks in advance. 

</details>


# 答案1
**得分**: 4

如果您使用的是JDK 11，您可以编写以下代码：

```java
for (int i = 0; i < 5; i++) {
    System.out.println("*".repeat(i + 1));
}

通过String.repeat()，您可以用更少的代码实现相同的效果。

for(int i = 0; i < 5; i++) {
    System.out.println("*".repeat(i+1));
}

答案2

得分: 2

Your for-loop seems strange.

The loop should be read like this:

"For int i starting at 0, loop as long as i<5 and after every iteration, do i++"

for(int i = 0; i<5; i++){
   System.out.println("*" \n);
}

This will print 5 rows:

*

*

*

*

*

Now in every row, you want one more *, and you might want to remove the \n which is already included in println. So instead of printing "*", you create a String before the loop and you add one new * to it every iteration:

String line = "";             // we start with an empty string
for(int i=0; i<5; i++){      
   line = line + "*";           // before printing we add a new *
   System.out.println(line); // then we print it 
}

It should (haven't tested it) result in this:

*
**
***
****
*****

for(int i = 0; i<5, i++){
   System.out.println("*" \n);
}

*

*

*

*

*

String line ="";             // we start with an empty string
for(int i=0; i<5; i++){      
   line= line+"*";           // before printing we add a new *
   System.out.println(line); // then we print it 
}

*
**
***
****
*****

答案3

得分: 1

以下是您要的翻译内容：

尝试这段代码：

    public class Main {
        public static void main(String[] args) {

            int i, j, n = 5;
            for(i = 0; i < n; i++) {
                for(j = 0; j <= i; j++) {
                    System.out.print("*");
                }
                System.out.println();
            }
        }
    }

public class Main {
	public static void main(String[] args) {

		int i, j, n =5;  
        for(i=0; i<n; i++) {           
            for(j=0; j<=i; j++) {       
                System.out.print("*");
            }
            System.out.println();
        }
    }     	
}