This post covers the following topics on search and filter:
– Search for a sub string or char in a string
– Search for a string in a list
– Filter a string in a list
– Filter a sub string in a list
– Search for a string in an array
Example 1: Search for a sub string or char in a string
String.contains() matches the exact input string, or a sub string, or a character.
private void searchSring()
{
String str = “abc3xy1cz”;
System.out.printf( “Original string: %s %n”, str );
System.out.printf( “Contains c3: %s %n”, str.contains( “c3” ) );
System.out.printf( “Contains A: %s %n”, str.contains( “A” ) );
System.out.printf( “Contains Z: %s %n”, str.contains( “Z” ) );
System.out.printf( “Contains Z: %s %n”, str.toLowerCase().contains( “Z”.toLowerCase() ) );
}
Output:
Original string: abc3xy1cz
Contains c3: true
Contains A: false
Contains Z: false
Contains Z: true
Example 2: Search for a string in a list
List.contains() searches for the exact input string.
private void searchList()
{
List<String> originalList = new ArrayList<String>();
originalList.add( “abc” );
originalList.add( “a7c” );
originalList.add( “xyZ” );
System.out.printf( “Original list: %s %n”, originalList );
System.out.printf( “Contains a: %s %n”, originalList.contains( “a” ) );
System.out.printf( “Contains abc: %s %n”, originalList.contains( “abc” ) );
}
Output:
Original list: [abc, a7c, xyZ]
Contains a: false
Contains abc: true
Example 3: Filter a string in a list
Filter out elements in a list which exactly matches the input string.
private void filterList()
{
List<String> originalList = new ArrayList<String>();
originalList.add( “abc” );
originalList.add( “ABC” );
originalList.add( “a7c” );
originalList.add( “xyZ” );
List<String> filteredList = new ArrayList<String>();
String[] originalArray = { “abc”, “x” };
for ( String str : originalArray )
{
if ( originalList.contains( str ) )
{
filteredList.add( str );
}
}
System.out.printf( “Original list: %s, Filtered list: %s %n”, originalList, filteredList );
}
Output:
Original list: [abc, ABC, a7c, xyZ], Filtered list: [abc]
Example 4: Filter a sub string in a list
Filter out elements in a list which matches the input sub string.
private void filterListSubString()
{
List<String> originalList = new ArrayList<String>();
originalList.add( “abc” );
originalList.add( “ABC” );
originalList.add( “a7c” );
originalList.add( “xyZ” );
List<String> filteredList = originalList.stream()
.filter( str -> str.contains( “a” ) )
.collect( Collectors.toList() );
System.out.printf( “Original list: %s, Filtered list: %s %n”, originalList, filteredList );
}
Output:
Original list: [abc, ABC, a7c, xyZ], Filtered list: [abc, a7c]
Example 5: Search for a string in an array
Methods contains(), or stream anyMatch() can be used to check if a string exactly matches with the elements in an array.
private void searchArray()
{
String[] originalArray = { “aaa”, “bbb”, “ccc” };
System.out.printf( “Original array: %s %n”, Arrays.asList( originalArray ) );|
System.out.printf( “Contains a: %s %n”, Arrays.asList( originalArray ).contains( “a” ) );
System.out.printf( “Contains aaa: %s %n”, Arrays.asList( originalArray ).contains( “aaa” ) );
System.out.printf( “AnyMatch a: %s %n”, Arrays.stream( originalArray ).anyMatch( “a” :: equals ) );
System.out.printf( “AnyMatch aaa: %s %n”, Arrays.stream( originalArray ).anyMatch( “aaa” :: equals ) );
System.out.printf( “AnyMatch AAA: %s %n”, Arrays.stream( originalArray ).anyMatch( “AAA” :: equalsIgnoreCase ) );
}
Output:
Original array: [aaa, bbb, ccc]
Contains a: false
Contains aaa: true
AnyMatch a: false
AnyMatch aaa: true
AnyMatch AAA: true