Java - Überprüfen Sie, ob das Array einen bestimmten Wert enthält?
Java-Beispiele, um zu überprüfen, ob ein Array (String- oder Primitivtyp) bestimmte Werte enthält, die mit Java 8-Stream-APIs aktualisiert wurden.
1. String-Arrays
1.1 Check if a String Array contains a certain value “A”.
StringArrayExample1.java
package com.example.core; import java.util.Arrays; import java.util.List; public class StringArrayExample1 { public static void main(String[] args) { String[] alphabet = new String[]{"A", "B", "C"}; // Convert String Array to List Listlist = Arrays.asList(alphabet); if(list.contains("A")){ System.out.println("Hello A"); } } }
Ausgabe
Hello A
In Java 8 können Sie dies tun:
// Convert to stream and test it boolean result = Arrays.stream(alphabet).anyMatch("A"::equals); if (result) { System.out.println("Hello A"); }
1.2 Example to check if a String Array contains multiple values :
StringArrayExample2.java
package com.example.core; import java.util.Arrays; import java.util.List; public class StringArrayExample2 { public static void main(String[] args) { String[] alphabet = new String[]{"A", "C"}; // Convert String Array to List Listlist = Arrays.asList(alphabet); // A or B if (list.contains("A") || list.contains("B")) { System.out.println("Hello A or B"); } // A and B if (list.containsAll(Arrays.asList("A", "B"))) { System.out.println("Hello A and B"); } // A and C if (list.containsAll(Arrays.asList("A", "C"))) { System.out.println("Hello A and C"); } } }
Ausgabe
Hello A or B Hello A and C
2. Primitive Arrays
2.1 For primitive array like int[]
, you need to loop it and test the condition manually :
PrimitiveArrayExample1.java
package com.example.core; import java.util.Arrays; import java.util.List; public class PrimitiveArrayExample1 { public static void main(String[] args) { int[] number = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; if(contains(number, 2)){ System.out.println("Hello 2"); } } public static boolean contains(final int[] array, final int v) { boolean result = false; for(int i : array){ if(i == v){ result = true; break; } } return result; } }
Ausgabe
Hello 2
2.2 With Java 8, coding is much simpler ~
ArrayExample1.java
package com.example.core; import java.util.stream.IntStream; import java.util.stream.LongStream; public class TestDate { public static void main(String[] args) { int[] number = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; //Java 8 boolean result = IntStream.of(number).anyMatch(x -> x == 4); if (result) { System.out.println("Hello 4"); } else { System.out.println("Where is number 4?"); } long[] lNumber = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}; boolean result2 = LongStream.of(lNumber).anyMatch(x -> x == 10); if (result2) { System.out.println("Hello 10"); } else { System.out.println("Where is number 10?"); } } }
Ausgabe
Hello 4 Hello 10
Note
Um zu überprüfen, ob ein primitives Array mehrere Werte enthält, konvertieren Siethe array
into a List und vergleichen Sie es wie in Beispiel 1.2 oben.