带输入的简单Java 2D数组

Question

I'm new to Java and got some work at school. Now I don't know how to continue and I hope you can help me.

That's my code till now

    package bp;
import java.util.Scanner;

public class BenzinP {

    private int row = 4;
    private int col = 4;
    private int[][] matrix;

    public BenzinP(int trow, int tcol) {

        this.row = trow;
        this.col = tcol;
    }

    public BenzinP(int trow, int tcol, int[][] m) {

        this.row = trow;
        this.col = tcol;
        this.matrix = m;
    }
    public int[][] fill(){ 
        int[][] data = new int[row][col]; 
        Scanner in = new Scanner(System.in);
        for(int row = 0; row< matrix.length; row++){ 
              for(int col = 0 ;col< matrix.length; col++){ 
                  System.out.println("Date"); 
                  data[row][0] = in.nextInt(); 
                  System.out.println("Price"); 
                  data[row][1] = in.nextInt(); 
               }
              System.out.println(); 
          } 

           for(int row = 0; row< matrix.length; row++){
       for(int col = 0 ;col< matrix[row].length; col++){ 
             System.out.print(data[row][col]);
       } 
      System.out.println(); 
   }
         return data; 
    }



    public static void main(String[] args){
        int[][] ma = new int[3][2];
        BenzinP q2 = new BenzinP(3, 2,ma);
        q2.fill();
    }
}

The task is: Create a Java program which can save the prices for gas for different days and can be outputted in different formats (sort for highes price or date). You should use a 2D Array which can safe data for at least 30 days. Also it should show the average, min. and max price. Also the program should be outsourced in methodes etc.

I hope you can help and keep it simple.

Answer 1

I will make some assumptions in order to be able to answer this:

if BenzinP is a class, that should not contain the main method. Only the main class in your project should contain the main, since that is what the JVM expects to be the "point of entry" in your code.

public static void main(String[] args)

Since this is an exercise, dont worry so far about this.

Then, the BenzinP class has 2 constructors that are not really needed.

I suggest the following:

BenzinP(){
   this.matrix=new int[this.row][this.col];
}

Create the rest of the methods you want, such as query the highest value, lowest, etc.. and start your main

public static void main(String[] args){
    BenzinP q2 = new BenzinP();
    q2.fill();
    q2.getHighest();
    // q2.getLowest();
    // q2.getEtc();
}

As a suggestion, in order to search the highest and lowest value, iterate your array and compare that value with an initialized one, if its bigger/smaller, update the value, at the end of the array, return the initialized value:

public int getHighest(){
   int max = -2147483648; // the lowest possible integer.
   for(int i=0 i<this.row;i++){
      if(matrix[i][1]>max){
         max = matrix[i][1];
      }
   }
   return max;
}