如何从文本文件但每3行读取ArrayList

Question

Here is the sample text file:

Brisbane
03163012
Australia
Tokyo
041022200
Japan

now I want to read three data together then put in different variables. Then take another three and so on.

location = brisbane;  
phoneNumber  = 03163012;
country = Australia; 

Afterwards, passed into the constructor.

And there is a MAXIMUM LOCATION = 10 that have to be read

public boolean data()
{
boolean isValid = true;
boolean check = true;
int a = 0;

try
{
    BufferedReader reader = new BufferedReader(newFileReader("location.txt"));
    String data = reader.readLine();

    while (data != null && check)
    {
        if (a != MAX_NUMBER)
        {
            for (int i = 0; i < 3; i++)
            {
                ?????????
                locations.add(newLocation);
                a++;
            }
        else
            check = false;

        data =reader.readLine;
        }
}
reader.close();
}

Can anyone help me with this one. I dont know what should I write in ???? thanks in advance

Answer 1

You probably want something like this inside your for loop:

            locations.add(data);
            data = reader.readLine();
            if(data!=null) 
                phoneNumber.add(data);
            else
                break;
            data = reader.readLine();
            if(data!=null) 
                country.add(data);
            else
                break;
            a++;

You want to read 3 lines, and add to locations, then phoneNumber, then country. There's all kinds of other problems with your code though (like a misplaced } and newFileReader )

Answer 2

Use Guava's method that reads file by lines and gives output as List<String>

Files.readLines(java.io.File, java.nio.charset.Charset)

Using it will make your code look much simplier, you will get rid of all those try-catch-finally and file buffers.

Iterate that list and use those strings as variables for:

location = brisbane;  
phoneNumber  = 03163012;
country = Australia;

iterating can look like this:

public static void main(String[] args) {

            //it's you a mock
    List<String> lines = new ArrayList<String>();
    lines.add("a");
    lines.add("1");
    lines.add("aa");

    lines.add("b");
    lines.add("2");
    lines.add("bb");


            //Iterating String from file.
    for (int i = 0; i < lines.size(); i += 3) {

        String location = lines.get(i);
        String phoneNumber = lines.get(i + 1);
        String country = lines.get(i + 2);

                    //somehow use red variables
        System.out.println(location);
        System.out.println(phoneNumber);
        System.out.println(country);
    }
}

Note that in code above I filled my list, yours fill be filled after reading file.

Answer 3

What you need is another object for location, so you can store your values like this:

String data = reader.readLine();
int counter = 0;
MyLocation newLocation = null;
while (data != null && ((counter/3) != MAX_NUMBER)){
    switch(counter % 3){
        case 0:
            newLocation = new MyLocation();
            newLocation.setLocation(data);
            break;
        case 1:
            newLocation.setPhone(data);
            break;
        case 2:
            newLocation.setCountry(data);
            locations.add(newLocation);
            newLocation = null;
            break;
    }
    counter++;
}

if(null != newLocation){
    //Error management
}

The MyLocation class will look like this:

private String location = null;

private String phone = null;

private String country = null;

public String getLocation() {
    return location;
}

public void setLocation(String location) {
    this.location = location;
}

public String getPhone() {
    return phone;
}

public void setPhone(String phone) {
    this.phone = phone;
}

public String getCountry() {
    return country;
}

public void setCountry(String country) {
    this.country = country;
}