在ArrayList中连接字符串和双精度

Question

Is it possible to connect a string and a double in a ArrayList ?

It should look this way:

[itemA 1, itemB 10, itemC 5, ...]

I tried it with write the double also as String in the ArrayList , but then
Collections.sort(list) won't sort the doubles correct.

Answer 1

That's when you make a class.

class MyObject {
 private String someString;
 private double someDouble;
 // Getters & setters
}

List<MyObject> myList = new ArrayList<>();

You can just keep a list of this custom object.

If you want to be able to sort your list on the double value, simply construct your class to implement the Comparable interface.

class MyObject : Comparable<MyObject>{
 private String someString;
 private double someDouble;

 @override
 public int compareTo(MyObject o) {
     return this.someDouble.compareTo(o.getSomeDouble());
 }
}

Answer 2

You can use Pair from apache commons:

List<Pair<String, Double>> list = new ArrayList<>();

list.add(new ImmutablePair<>("STRING", 2.0));

Answer 3

You can create a class like, MyClass and create a String variable and double value.

Like,

class MyClass
{
   private String strVlaue;

   private String doubleValue;

   //Constructor using fields, and getter/setter method
}

Since you want to make it in order by double Value.

You can either make MyClass implement Comparable and implement custom order in compareTo method OR create a comparator for MyClass

1 Implements Comparable

public class MyClass implements Comparable {

private String strVlaue;

private double doubleValue;

public MyClass(String strVlaue, double doubleValue) {
    this.strVlaue = strVlaue;
    this.doubleValue = doubleValue;
}

@Override
public int compareTo(Object o) {

    MyClass mc = (MyClass) o;

    return Double.compare(this.doubleValue, mc.getDoubleValue());
}

public String getStrVlaue() {
    return strVlaue;
}

public void setStrVlaue(String strVlaue) {
    this.strVlaue = strVlaue;
}

public double getDoubleValue() {
    return doubleValue;
}

public void setDoubleValue(double doubleValue) {
    this.doubleValue = doubleValue;
}
}

Use Collections.sort(List<MyClass>) to sort.

2 Keep MyClass not implement Comparable, create a comparator.

public class MyComparator implements Comparator<MyClass>{

@Override
public int compare(MyClass o1, MyClass o2) {

    return Double.compare(o1.getDoubleValue(), o2.getDoubleValue());
}

}

Use Collections.sort(List<MyClass>, new MyComparator()) to sort.