整理網路文章方法小記。
list - Get unique values from ArrayList in Java - Stack Overflow
1
2
3
4
5
|
List<String> gasList = // create list with duplicates...
Set<String> uniqueGas = new HashSet<String>(gasList);
System.out.println("Unique gas count: " + uniqueGas.size());
uniqueGas.toArray(new String[0]);
|
1
2
3
4
|
String[] unique = new HashSet<String>(Arrays.asList(array)).toArray(new String[0]);
and shorter and simpler in java 8:
String[] unique = Arrays.stream(array).distinct().toArray(String[]::new);
|
java - Array of unique elements? - Stack Overflow
1
|
int[] noDuplicates = IntStream.of(array).distinct().toArray();
|
Java 8 stream distinct by multiple fields - HowToDoInJava
移除 null 方法
Java program to remove nulls from a List Container
各種寫法…大神啦!!
Java program to remove nulls from a List Container - GeeksforGeeks
備份圖
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
|
import java.util.*;
class GFG {
public static void main(String[] args)
{
// Create the list with null values
List<String> list = new ArrayList<>(
Arrays.asList("Geeks",
null,
"forGeeks",
null,
"A computer portal"));
// Print the list
System.out.println("Initial List: " + list);
// Removing nulls using List.remove()
// Repeatedly call remove() till all null are removed
while (list.remove(null)) {
}
// Print the list
System.out.println("Modified List: " + list);
}
}
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
|
import com.google.common.base.Predicates;
import com.google.common.collect.Iterables;
import java.util.*;
class GFG {
public static void main(String[] args)
{
// Create the list with null values
List<String> list = new ArrayList<>(
Arrays.asList("Geeks",
null,
"forGeeks",
null,
"A computer portal"));
// Print the list
System.out.println("Initial List: " + list);
// Removing nulls using Guava Iterables
// using Predicate condition isNull()
Iterables.removeIf(list, Predicates.isNull());
// Print the list
System.out.println("Modified List: " + list);
}
}
|