如何使用函數增加和減少值

Question

嗨，大家好，我是Java的新手。我創建了第一個程序。 但我無法獲得所需的輸出。

我想將j的值設置為2，然后我想讓其值保持不變，直到循環結束。但是我沒有得到該值

    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

請提供一個最小的工作示例。 您的代碼甚至無法編譯（方法之外的代碼，“ voide”而不是void）。 無論如何，我整理出一些適合您的方法：

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);}  
    }

}

輸出如下。 那是您期望的嗎？

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

Answer 2

使用j和i作為static int變量，例如static int i