java - 如何使用函数增加和减少值

Question

大家好，我是 Java 新手。我已经创建了第一个程序。但我无法获得所需的输出..

我希望 j 值为 2，然后我想增加 i 值直到循环结束。但我没有得到该值

    private double i=30;
    private double j=20; 

    private double l=5;



if (l=5)
{

for (; j<=50  ; j+=2)
{
     System.out.printf("value of j is %d\n",j);
     increamenti_Value ();

}
for (; j>=4; j-=2) // i want here the value j to be 20 ... 

{
     System.out.printf("value of decrement is %d\n",j);
      increamenti_Value ();
}

}


private voide increamenti_Value ()

for (; i<=50  ; i+=2)
{
     System.out.printf("value of i is %d\n",i);


}
for (; i>=4; i-=2) // i want here the value j to be 20 ... 

{
     System.out.printf("value of decrement is %d\n",i);
}

Answer 1

请提供一个最小的工作示例。您的代码甚至无法编译(方法之外的代码，“voide”而不是 void)。不管怎样，我整理了一些对你有用的东西:

package test;

public class Test
{
    static private int i=30;
    static private int  j=20; 
    static private int l=5;

    public static void main(String[] args)
    {
        if (l==5)
        {

            for (; j<=50  ; j+=2)
            {
                System.out.printf("value of j is %d\n",j);
                increamenti_Value ();
            }
            for (; j>=4; j-=2) // i want here the value j to be 20 ... 

            {
                System.out.printf("value of decrement is %d\n",j);
                increamenti_Value ();
            }
        }
    }

    private static void increamenti_Value ()
    {
        for (; i<=50  ; i+=2) {System.out.printf("value of i is %d\n",i);}  
    }

}

输出如下。这是你所期望的吗？

value of j is 20
value of i is 30
value of i is 32
value of i is 34
value of i is 36
value of i is 38
value of i is 40
value of i is 42
value of i is 44
value of i is 46
value of i is 48
value of i is 50
value of j is 22
value of j is 24
value of j is 26
value of j is 28
value of j is 30
value of j is 32
value of j is 34
value of j is 36
value of j is 38
value of j is 40
value of j is 42
value of j is 44
value of j is 46
value of j is 48
value of j is 50
value of decrement is 52
value of decrement is 50
value of decrement is 48
value of decrement is 46
value of decrement is 44
value of decrement is 42
value of decrement is 40
value of decrement is 38
value of decrement is 36
value of decrement is 34
value of decrement is 32
value of decrement is 30
value of decrement is 28
value of decrement is 26
value of decrement is 24
value of decrement is 22
value of decrement is 20
value of decrement is 18
value of decrement is 16
value of decrement is 14
value of decrement is 12
value of decrement is 10
value of decrement is 8
value of decrement is 6
value of decrement is 4