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Java 8 Streams - Stream.allMatch Examples

Java 8 Streams Java Java API 

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Interface:

java.util.stream.Stream

java.lang.AutoCloseableAutoCloseablejava.util.stream.BaseStreamBaseStreamjava.util.stream.StreamStreamLogicBig

Method:

boolean allMatch(Predicate<? super T> predicate)

This terminal-short-circuiting operation returns whether all elements match the provided predicate criteria. It returns 'false' on finding the first mismatch hence short-circuiting (just like boolean && operator).

If the stream is empty then this method returns true and the predicate is not evaluated.


Examples


package com.logicbig.example.stream;

import java.util.Arrays;
import java.util.List;

public class AllMatchExample {

    public static void main(String... args) {
        List<Integer> list = Arrays.asList(2, 4, 6, 8);
        boolean b = list.stream().allMatch(i -> i % 2 == 0);
        System.out.println(b);
    }
}

Output

true




package com.logicbig.example;

import java.util.stream.Stream;

public class AllMatchExample {
    public static void main (String[] args) {
        Stream<String> stream = Stream.of("one", "two", "Three", "four");
        boolean match = stream.allMatch(s -> s.length() > 0 &&
                            Character.isLowerCase(s.charAt(0)));
        System.out.println(match);
    }
}

Output

false
Original Post




An empty stream will return true 

package com.logicbig.example.stream;

import java.util.ArrayList;

public class AllMatchExample2 {

    public static void main(String... args) {
        boolean b = new ArrayList<>().stream()
                                     .allMatch(e -> false);
        System.out.println(b);
    }
}

Output

true

See Also