Java值对集合？ （元组？）

#1 楼

public class Pair<L,R> {

  private final L left;
  private final R right;

  public Pair(L left, R right) {
    assert left != null;
    assert right != null;

    this.left = left;
    this.right = right;
  }

  public L getLeft() { return left; }
  public R getRight() { return right; }

  @Override
  public int hashCode() { return left.hashCode() ^ right.hashCode(); }

  @Override
  public boolean equals(Object o) {
    if (!(o instanceof Pair)) return false;
    Pair pairo = (Pair) o;
    return this.left.equals(pairo.getLeft()) &&
           this.right.equals(pairo.getRight());
  }

}

#2 楼

java.util.List<java.util.Map.Entry<String,Integer>> pairList= new java.util.ArrayList<>();

java.util.Map.Entry<String,Integer> pair1=new java.util.AbstractMap.SimpleEntry<>("Not Unique key1",1);
java.util.Map.Entry<String,Integer> pair2=new java.util.AbstractMap.SimpleEntry<>("Not Unique key2",2);
pairList.add(pair1);
pairList.add(pair2);

Entry<String,Integer> pair1=new SimpleEntry<>("Not Unique key1",1);
Entry<String,Integer> pair2=new SimpleEntry<>("Not Unique key2",2);
pairList.add(pair1);
pairList.add(pair2);

pairList.add(createEntry("Not Unique key1", 1));
pairList.add(createEntry("Not Unique key2", 2));

TupleList<java.util.Map.Entry<String,Integer>> pair = new TupleList<>();
pair.of("Not Unique key1", 1);
pair.of("Not Unique key2", 2);

#3 楼

@Value
public class Pair<K, V> {
    K key;
    V value;
}

import java.util.Objects;

public class Pair<K, V> {

    public final K key;
    public final V value;

    public Pair(K key, V value) {
        this.key = key;
        this.value = value;
    }

    public boolean equals(Object o) {
        return o instanceof Pair && Objects.equals(key, ((Pair<?,?>)o).key) && Objects.equals(value, ((Pair<?,?>)o).value);
    }

    public int hashCode() {
        return 31 * Objects.hashCode(key) + Objects.hashCode(value);
    }

    public String toString() {
        return key + "=" + value;
    }
}

#4 楼

#5 楼

List<Pair<String, Integer>> myPairs = new ArrayList<Pair<String, Integer>>();
myPairs.add(Pair.of("val1", 11));
myPairs.add(Pair.of("val2", 17));

//...

for(Pair<String, Integer> pair : myPairs) {
  //following two lines are equivalent... whichever is easier for you...
  System.out.println(pair.getLeft() + ": " + pair.getRight());
  System.out.println(pair.getKey() + ": " + pair.getValue());
}

#6 楼

#7 楼

    import org.apache.commons.lang3.tuple.ImmutablePair;
    import org.apache.commons.lang3.tuple.Pair;
    ...
    @SuppressWarnings("unchecked")
    Pair<String, Integer>[] arr = new ImmutablePair[]{
            ImmutablePair.of("A", 1),
            ImmutablePair.of("B", 2)};

    // both access the 'left' part
    String key = arr[0].getKey();
    String left = arr[0].getLeft();

    // both access the 'right' part
    Integer value = arr[0].getValue();
    Integer right = arr[0].getRight();

        <dependency>
            <groupId>org.apache.commons</groupId>
            <artifactId>commons-lang3</artifactId>
            <version>3.4</version>
        </dependency>

#8 楼

#9 楼

class Pair<L,R> {
      final L left;
      final R right;

      public Pair(L left, R right) {
        this.left = left;
        this.right = right;
      }

      static <L,R> Pair<L,R> of(L left, R right){
          return new Pair<L,R>(left, right);
      }
}

    list.add(Pair.of(x,y)); // my preference
    list.add(pairOf(x,y)); // use with import static x.y.Pair.pairOf

#10 楼

#11 楼

#12 楼

//======>  Imports
import java.util.AbstractMap.SimpleEntry;
import java.util.ArrayList;
import java.util.List;
import java.util.Map.Entry;

//======>  Single Entry
SimpleEntry<String, String> myEntry = new SimpleEntry<String, String>("ID", "Text");
System.out.println("key: " + myEntry.getKey() + "    value:" + myEntry.getValue());
System.out.println();

//======>  List of Entries
List<Entry<String,String>> pairList = new ArrayList<>();

//-- Specify manually
Entry<String,String> firstButton = new SimpleEntry<String, String>("Red ", "Way out");
pairList.add(firstButton);

//-- one liner:
pairList.add(new SimpleEntry<String,String>("Gray", "Alternate route"));  //Ananomous add.

//-- Iterate over Entry array:
for (Entry<String, String> entr : pairList) {
    System.out.println("Button: " + entr.getKey() + "    Label: " + entr.getValue());
}

#13 楼

#14 楼

class tuples 
{ 
int x;
int y;
} 

List<tuples> list = new ArrayList<tuples>();

#15 楼

public static void main(String []args)
{    
    HashMap<String, Integer> values = new HashMap<String,Integer>();
    values.put("A", 235);//your custom data, the types may be different
    //more data insertions....
    Set<Map.Entry<String,Integer>> list = values.entrySet();//your list 
    //do as you may with it
}

#16 楼

Pair<String,Integer> pair = Pair.of("Test", 123);
System.out.println(pair.getFirst());
System.out.println(pair.getSecond());

#17 楼

#18 楼

#19 楼

Tuple2<String, Integer> t = Tuples.of("string", 1)

Stream<Tuple2<String, Integer>> s;
s.map(t -> t.mapT2(i -> i + 2));