Java – Stream has already been operated upon or closed

package com.mkyong.java8;

import java.util.Arrays;
import java.util.stream.Stream;

public class TestJava8 {

public static void main(String[] args) {

String[] array = {"a", "b", "c", "d", "e"};
Stream<String> stream = Arrays.stream(array);

// loop a stream
stream.forEach(x -> System.out.println(x));

// reuse it to filter again! throws IllegalStateException
long count = stream.filter(x -> "b".equals(x)).count();
System.out.println(count);

}

Output

java.lang.IllegalStateException: stream has already been operated upon or closed
at java.util.stream.AbstractPipeline.(AbstractPipeline.java:203)
at java.util.stream.ReferencePipeline.(ReferencePipeline.java:94)
at java.util.stream.ReferencePipeline$StatelessOp.(ReferencePipeline.java:618)
at java.util.stream.ReferencePipeline$2.(ReferencePipeline.java:163)
at java.util.stream.ReferencePipeline.filter(ReferencePipeline.java:162)
at com.hostingcompass.whois.range.run.TestJava8.main(TestJava8.java:25)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

2. Example – Reuse a stream
package com.mkyong.java8;

import java.util.function.Supplier;
import java.util.stream.Stream;

public class TestJava8 {

public static void main(String[] args) {

String[] array = {"a", "b", "c", "d", "e"};

Supplier<Stream<String>> streamSupplier = () -> Stream.of(array);

//get new stream
streamSupplier.get().forEach(x -> System.out.println(x));

//get another new stream
long count = streamSupplier.get().filter(x -> "b".equals(x)).count();
System.out.println(count);

}

}
Output

a
b
c
d
e
1

http://www.mkyong.com/java8/java-stream-has-already-been-operated-upon-or-closed/

巴特西

Java – Stream has already been operated upon or closed

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