java.util.AbstractSequentialList类的retainAll()方法用于从此列表保留指定集合中包含的所有元素。
用法:
public boolean retainAll(Collection c)
参数:此方法将集合c作为包含要从此列表保留的元素的参数。
返回值:如果此列表由于调用而更改,则此方法返回true。
异常:如果此列表包含null元素并且指定的集合不允许null元素(可选),或者指定的collection为null,则此方法引发NullPointerException。
以下示例说明了retainAll()方法。
范例1:
// Java program to demonstrate
// retainAll() method for Integer value
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// Creating object of AbstractSequentialList<Integer>
AbstractSequentialList<Integer>
arrlist1 = new LinkedList<Integer>();
// Populating arrlist1
arrlist1.add(1);
arrlist1.add(2);
arrlist1.add(3);
arrlist1.add(4);
arrlist1.add(5);
// print arrlist1
System.out.println("AbstractSequentialList before "
+ "retainAll() operation:"
+ arrlist1);
// Creating another object of AbstractSequentialList<Integer>
AbstractSequentialList<Integer>
arrlist2 = new LinkedList<Integer>();
arrlist2.add(1);
arrlist2.add(2);
arrlist2.add(3);
// print arrlist2
System.out.println("Collection Elements"
+ " to be retaind:"
+ arrlist2);
// Removing elements from arrlist
// specified in arrlist2
// using retainAll() method
arrlist1.retainAll(arrlist2);
// print arrlist1
System.out.println("AbstractSequentialList after "
+ "retainAll() operation:"
+ arrlist1);
}
catch (NullPointerException e) {
System.out.println("Exception thrown:" + e);
}
}
}
输出:
AbstractSequentialList before retainAll() operation:[1, 2, 3, 4, 5] Collection Elements to be retaind:[1, 2, 3] AbstractSequentialList after retainAll() operation:[1, 2, 3]
范例2:对于NullPointerException
// Java program to demonstrate
// retainAll() method for Integer value
import java.util.*;
public class GFG1 {
public static void main(String[] argv) throws Exception
{
try {
// Creating object of AbstractSequentialList<Integer>
AbstractSequentialList<Integer>
arrlist1 = new LinkedList<Integer>();
// Populating arrlist1
arrlist1.add(1);
arrlist1.add(2);
arrlist1.add(3);
arrlist1.add(4);
arrlist1.add(5);
// print arrlist1
System.out.println("AbstractSequentialList before "
+ "retainAll() operation:"
+ arrlist1);
// Creating another object of AbstractSequentialList<Integer>
AbstractSequentialList<Integer>
arrlist2 = null;
// print arrlist2
System.out.println("Collection Elements"
+ " to be retaind:"
+ arrlist2);
System.out.println("\nTrying to pass "
+ "null as a specified element\n");
// Removing elements from arrlist
// specified in arrlist2
// using retainAll() method
arrlist1.retainAll(arrlist2);
// print arrlist1
System.out.println("AbstractSequentialList after "
+ "retainAll() operation:"
+ arrlist1);
}
catch (NullPointerException e) {
System.out.println("Exception thrown:" + e);
}
}
}
输出:
AbstractSequentialList before retainAll() operation:[1, 2, 3, 4, 5] Collection Elements to be retaind:null Trying to pass null as a specified element Exception thrown:java.lang.NullPointerException
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注:本文由纯净天空筛选整理自Code_r大神的英文原创作品 AbstractSequentialList retainAll() method in Java with Example。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。