Question

Using Java

1.) Write Integers to a File – This time build a class WriteInts. This class, when instantiated, will create a new file and write an array of integers to this new file. All the code to write the data to the file goes in the Constructor.

[i.e.   // This code goes in main()

int myArr[] = {16, 31, 90, 45, 89};

        WriteInts wi = new WriteInts(“mydata.dat”, myArr);   ]

2.) Read Integers from a File – This time build a class ReadInts. This class, when instantiated, will read the integers from the file given, and print them to the Console. All the code to write the data to the file goes in the Constructor.

[i.e.   // This code goes in main()

        ReadInts ri = new ReadInts(“mydata.dat”);     ]

3.) Write a String to a File using PrintStream – This time build a class WriteString. This class, when instantiated, will write a string to a file by using a PrintStream object connected to a FileOutputStream Object.

[i.e. // This code goes in main()

WriteString ws = new WriteString(“f1.txt”,“Hello world”);]

Answer 1

import java.io.FileNotFoundException;
import java.io.PrintWriter;

public class WriteInts {

    public WriteInts(String fileName, int arr[]){
        PrintWriter printWriter = null;
        try {
            printWriter = new PrintWriter(fileName);
            for(int i = 0; i < arr.length; ++i) {
                printWriter.println(arr[i]);
            }
            printWriter.flush();
            printWriter.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
}

public class TestWriteInts {

    public static void main(String[] args) {
        int myArr[] = {16, 31, 90, 45, 89};
        new WriteInts("mydata.dat", myArr);
    }

}

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