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Java Collections - Arrays.asList() Examples

Java Collections Java Java API 

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Class:

java.util.Arrays

java.lang.Objectjava.lang.Objectjava.util.Arraysjava.util.ArraysLogicBig

Method:

@SafeVarargs
public static <T> List<T> asList(T... a)

This method returns a fixed-size list backed by the specified array.


Examples


package com.logicbig.example.arrays;

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

public class AsListExample {

    public static void main(String... args) {
        String[] stringArray = {"one", "two", "three"};
        List<String> list = Arrays.asList(stringArray);
        System.out.println(list);
    }
}

Output

[one, two, three]




package com.logicbig.example.arrays;

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

public class AsListExample2 {

public static void main(String... args) {
    List<String> list = Arrays.asList("one", "two", "three");
    System.out.println(list);
}
}

Output

[one, two, three]




Changes to the source array reflect to the List and changes to the List reflect to the source array. 

package com.logicbig.example.arrays;

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

public class AsListExample3 {

    public static void main(String... args) {
        String[] stringArray = {"one", "two", "three"};
        List<String> list = Arrays.asList(stringArray);
        System.out.println(list);

        stringArray[0] = null;
        System.out.println(list);

        list.set(2, "last");
        System.out.println(Arrays.toString(stringArray));
    }
}

Output

[one, two, three]
[null, two, three]
[null, two, last]




Cannot add more elements to the List as it is fixed size. 

package com.logicbig.example.arrays;

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

public class AsListExample4 {

    public static void main(String... args) {
        String[] stringArray = {"one", "two", "three"};
        List<String> list = Arrays.asList(stringArray);
        list.add("four");
    }
}

Output

Caused by: java.lang.UnsupportedOperationException
	at java.util.AbstractList.add(AbstractList.java:148)
	at java.util.AbstractList.add(AbstractList.java:108)
	at com.logicbig.example.arrays.AsListExample4.main(AsListExample4.java:17)
	... 6 more

See Also