java - 在java中通过方法使用数组，返回数组

Question

提示:http://puu.sh/lvdIG/404ebfba03.png

我快完成了。我需要修复我遇到的三个错误:在 treeReport+= line 上，我收到错误:"cannot find symbol"for minSeeds, totalSeeds 和 totalTrees。我不能将它们声明为类的成员，也不能在它们之前使用 static。我也只能使用一个类。

import javax.swing.JOptionPane;

public class TreeCalc {

    public static void main(String[] args) {
        String[] treeTypes = new String[] {"Fir", "Pine", "Spruce"};
        int[] desiredYield = new int[treeTypes.length];
        double[] decayRate = new double[] {0.07, 0.12, 0.08};
        desiredYield = getYield(decayRate, desiredYield, treeTypes);
        getCalculate(decayRate, desiredYield, treeTypes);
        printMessage(decayRate, desiredYield, treeTypes);
    }

    //Asks user to input # of trees for each tree type
    public static int[] getYield(double[] decayRate, int[] desiredYield, String[] treeTypes) {
        int index = 0;
        for (int i = 0; i < treeTypes.length; i++) {
            try {
                desiredYield[index] = Integer.parseInt(JOptionPane.showInputDialog("Please enter your desired yield for: " + treeTypes[i]));
            } catch (NumberFormatException e) {
                desiredYield[index] = 0;
                JOptionPane.showMessageDialog(null, "Error: Please enter your desired yield for " + treeTypes[i]);
            }
            if (desiredYield[index] <= 0) {
                JOptionPane.showMessageDialog(null, "Error: Please enter your desired yield for " + treeTypes[i]);
            } else {
                index++;
            }
        }
        return desiredYield;
    }

    //Calculates totals and minimums
    public static int[] getCalculate(double[] decayRate, int[] desiredYield, String[] treeTypes) {
        int totalSeeds = 0;
        int totalTrees = 0;
        int minSeeds = 0;
        int index = 0;
        for (int i = 0; i < treeTypes.length; i++) {
            minSeeds += (desiredYield[index] * (decayRate[index] * 7)) + desiredYield[index];
            totalSeeds += minSeeds;
            totalTrees += desiredYield[index];
        }
        return desiredYield;
    }

    public static void printMessage(double[] decayRate, int[] desiredYield, String[] treeTypes) {
        getCalculate(decayRate, desiredYield, treeTypes);
        String treeReport = "Tree Type | Minimum Seeds | Total Seeds | Total Trees ";
        for (int i = 0; i < treeTypes.length; i++) {
            treeReport += "\n" + treeTypes[i] + " " + minSeeds + " " + totalSeeds + " " + totalTrees;
        }
        JOptionPane.showMessageDialog(null, treeReport);
    }
}

Answer 1

不是从 getCalculate() 返回 desiredYield int 数组，您根本没有在 printMessage() 中使用它，您可以准备并返回一个更有意义的 int 数组，即包含 minSeeds、totalSeeds 和 totalTrees 的结果。然后在您的 printMessage() 中使用它。

这样，您就无需将这些变量声明为类级别或静态。这就是您的要求。

我在我的回答代码片段中用//Updated code... 注释了更新的代码，以方便您引用。

对于 int 数组，您需要使用基于索引的方法来访问数组，如果您希望使用更具可读性的方法，那么另一种方法可以准备并返回一个HashMap。

   public static int[] getCalculate(double[]decayRate, int[]desiredYield, String[]treeTypes){
  int totalSeeds =0;
  int totalTrees=0;
  int minSeeds=0;      
  int index=0;
  int[] finalResult = new int[3];  //Updated code...
  for(int i=0; i<treeTypes.length;i++){
      minSeeds+=(desiredYield[index] * (decayRate[index]*7))+desiredYield[index];
      totalSeeds+=minSeeds;
      totalTrees+=desiredYield[index];

      }
     finalResult[0] = minSeeds; //Updated code...
     finalResult[1] = totalSeeds; //Updated code...
     finalResult[2] = totalTrees; //Updated code...
   return finalResult; //Updated code...
}

   public static void printMessage(double[]decayRate, int[]desiredYield, String[]treeTypes){
   finalResult = getCalculate(decayRate, desiredYield, treeTypes); //Updated code...

   String treeReport = "Tree Type | Minimum Seeds | Total Seeds | Total Trees ";
   for(int i=0; i<treeTypes.length; i++){
    treeReport += "\n"+treeTypes[i] + " " + finalResult[0] + " " + finalResult[1] + " " + finalResult[2]; //Updated code...
   }
   JOptionPane.showMessageDialog(null, treeReport);
  }