如何在Java中使用LinkedList类？

Question

So I'm trying to design a program in java that provides average daily temperate (low and high) for a certain month of a year.I've created a class that include two methods one for the average low and one for the average high temperature.

Now I'm trying to add a method that consumes a date (day, month, year) and a List of readings (nominally for that date) and stores a daily report for the given date (computing the high and low temperature readings from the given list of readings for that date).

I am struggling with the last method, i don't fully understand how am i supposed to go on doing it (I am not supposed to enter examples for each day, rather just calculate the average of available readings of the days in a certain month).

So anyone could point me in the right direction, this is supposed to be a practice for using LinkedList class in java.

 Public class DailyReadings{

  int day;
  int month;
  int year;
  int highTemperature;
  int lowTemperature;

public DailyReading(int day, int month, int year, int highTemperature, int lowTemperature){

 this.day = day;
 this.month = month;
 this.year = year;
 this.highTemperature = highTemperature;
 this.lowTemperature= lowTemperature;
}

}

public class WeatherMonitor extends DailyReadings {


int averageHighForMonth (this.month, this.year) {
int tempHighAvg = 0;
int tempSum = 0;  
int x = 0;
for ( DailyReadings highTemperature : Report ) {
 if (this.month=this.month){
 tempSum = tempSum + highTemperature;
  x  = x++;
 }
 }
 tempHighAverage = tempSum/x; 
}
return tempHighAverage;
}

int averageLowForMonth (this.month, this.year){
 int tempLowAvg = 0;
 int tempSum = 0;
 int x = 0;
 for ( DailyReadings lowTemperature : Report ) {
  if (this.month = this.month) {
  tempSum = tempSum + lowTemperature;
  x  = x++;
  }
  }
 tempLowAverage = tempSum/x;
 } 
 return tempLowAverage;
}

int addDailyReport(int date, LinkedList<DailyReadings>  ) {



  }

 } 

class Examples {

 LinkedList<DailyReadings> Report = new  LinkedList<DailyReadings>;


}

Here's what I've go so far. I'm supposed to store some readings as described and use it in the "temperateHighAverage, and temperatureLowAverage). I'm not sure how to first create the list and also storing the data in it using the "addDailyReport" method.

Answer 1

Try this:

import java.util.Iterator;
import java.util.LinkedList;

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

        WeatherMonitor wM = new WeatherMonitor();

        DailyReadings dR = new DailyReadings(1,1,2020, 10, -20);
        wM.addDailyReport(dR);

        dR = new DailyReadings(1,2,2020, 10, -21);
        wM.addDailyReport(dR);

        dR = new DailyReadings(1,3,2020, 11, -20);
        wM.addDailyReport(dR);

        //...

        System.out.println(wM.averageHighForMonth(1, 2020));
        System.out.println(wM.averageLowForMonth(1, 2020));

    }
}


class DailyReadings {
    int day;
    int month;
    int year;
    int highTemperature;
    int lowTemperature;

    public DailyReadings(int day, int month, int year, int highTemperature, int lowTemperature){

        this.day = day;
        this.month = month;
        this.year = year;
        this.highTemperature = highTemperature;
        this.lowTemperature= lowTemperature;
    }
}

class WeatherMonitor {

    LinkedList<DailyReadings> Readings = new  LinkedList<DailyReadings>();

    int averageHighForMonth (int month, int year) {
        int tempHighAvg = 0;
        int count = 0;
        Iterator<DailyReadings> it =  Readings.iterator();
        DailyReadings tmp;
        while( (tmp = it.next()) != null) {
            if (tmp.month == month && tmp.year == year) {
                tempHighAvg += tmp.highTemperature;
                count++;
            }
        }
        return tempHighAvg / count;
    }

    int averageLowForMonth (int month, int year) {
        int tempLowAvg = 0;
        int count = 0;
        Iterator<DailyReadings> it =  Readings.iterator();
        DailyReadings tmp;
        while( (tmp = it.next()) != null) {
            if (tmp.month == month && tmp.year == year) {
                tempLowAvg += tmp.lowTemperature;
                count++;
            }
        }
        return tempLowAvg / count;
    }

    void addDailyReport(DailyReadings dR) {
        Readings.add(dR);
    }
} 

//-----------------------

But some points that you should know :

int averageLowForMonth (this.month, this.year){// This is wrong!

You cannot define a method this way, parameters should be defined like this:

(type name, type name ,...)

BTW, you should use Composition in situations like this, not Inheritance .

Answer 2

First of all, your list parameter needs a name, something like

 int addDailyReport(int date, LinkedList<DailyReadings> reportList ) 

Then you can use it inside the method and add the report with

  reportList.add(this);