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Java Articles
Page 374 of 450
How to count element after filtering in Java?
Let’s say the following is the String List:List list = new ArrayList(); list.add("Tom"); list.add("John"); list.add("David"); list.add("Paul"); list.add("Gayle"); list.add("Narine"); list.add("Joseph");Now, let’s say you need to filter elements beginning with a specific letter. For that, use filter() and startsWith():long res = list .stream() .filter((s) -> s.startsWith("J")) .count();We have also counted the elements above after filtering using count().The following is an example to count element after filtering in Java:Exampleimport java.util.ArrayList; import java.util.List; public class Demo { public static void main(final String[] args) { List list = new ArrayList(); list.add("Tom"); list.add("John"); ...
Read MoreHow to filter empty string values from a Java List?
Let’s say we have a String List with an empty value. Here, we have empty array elements before Football and after Squash:List sports = Arrays.asList("", "Football", "Cricket", "Tennis", "Squash", "", "Fencing", "Rugby");Now filter the empty string values. At first, we have used Predicate to negate values:Stream stream = sports.stream(); Predicate empty = String::isEmpty; Predicate emptyRev = empty.negate(); stream.filter(emptyRev).collect(Collectors.toList()));The following is an example to filter empty string values from a List:Exampleimport java.util.Arrays; import java.util.List; import java.util.function.Predicate; import java.util.stream.Collectors; import java.util.stream.Stream; public class Demo { public static void main(String[] args) { List sports = Arrays.asList("", "Football", "Cricket", "Tennis", ...
Read MoreHow to filter non-null value in Java?
Let’s say the following is our List with string elements:List leagues = Arrays.asList("BBL", "IPL", "MLB", "FPL", "NBA", "NFL");Now, create a stream and filter elements that end with a specific letter:Stream stream = leagues.stream().filter(leagueName -> leagueName.endsWith("L"));Now, use Objects::nonnull for non-null values:List list = stream.filter(Objects::nonNull).collect(Collectors.toList());The following is an example to filter non-null value in Java:Exampleimport java.util.Arrays; import java.util.List; import java.util.Objects; import java.util.stream.Collectors; import java.util.stream.Stream; public class Demo { public static void main(String[] args) { List leagues = Arrays.asList("BBL", "IPL", "MLB", "FPL", "NBA", "NFL"); Stream stream = leagues.stream().filter(leagueName -> leagueName.endsWith("L")); List list = ...
Read MoreHow can I check if there are any selected items in Java JList
To check if there are any selected items, use the following:boolean res = !list.isSelectionEmpty();The value of res would be TRUE IF we have a selected item in the JList.The following is an example to check if there are any selected items in JList:Examplepackage my; import java.awt.event.*; import java.awt.*; import javax.swing.*; class SwingDemo extends JFrame { static JFrame frame; static JList list; public static void main(String[] args) { frame = new JFrame("JList Demo"); SwingDemo s = new SwingDemo(); JPanel panel = new JPanel(); String sports[]= {"Squash", ...
Read MoreHow to display row count in Java Swing JList
Use JList getVisibleRowCount() method to display the row count in a JList:String sports[]= {"Tennis", "Archery", "Football", "Fencing", "Cricket", "Squash", "Hockey", "Rugby"}; Jlist list = new JList(sports); int rowCount = list.getVisibleRowCount(); System.out.println("Row Count = "+rowCount);The following is an example to display row count in JList:Exampleimport java.awt.event.*; import java.awt.*; import javax.swing.*; class SwingDemo extends JFrame { static JFrame frame; static JList list; public static void main(String[] args) { frame = new JFrame("JList Demo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); String sports[]= {"Tennis", Archery", "Football", "Fencing", "Cricket", "Squash", "Hockey", "Rugby"}; list = ...
Read MoreMap to create new value from int array in Java
Let’s say the following is our int array elements:10, 50, 100, 200, 250, 300, 400, 500Here, we are mapping and creating a new value by incrementing each int element with 1:Arrays.stream(new int[] {10, 50, 100, 200, 250, 300, 400, 500}).map(val -> val + 1)Now find the average:Arrays.stream(new int[] {10, 50, 100, 200, 250, 300, 400, 500}).map(val -> val + 1).average()The following is an example to Map and create new value from int array:Exampleimport java.util.Arrays; public class Demo { public static void main(String[] args) throws Exception { Arrays.stream(new int[] {10, 50, 100, 200, 250, 300, 400, 500}).map(val -> val + 1).average() .ifPresent(System.out::println); } }Output227.25
Read MoreJava Program to select the first item in JList
To select the first item in JList, use setSelectionInterval() method:String values[]= { "One", "Two", "Three", "Four", "Five", "Six"}; JList list = new JList(values); int begn = 0; int end = 0; list.setSelectionInterval(begn, end);The following is an example to select the first item in JList:Examplepackage my; import java.awt.event.*; import java.awt.*; import javax.swing.*; class SwingDemo extends JFrame { static JFrame frame; static JList list; public static void main(String[] args) { frame = new JFrame("JList Demo"); SwingDemo s = new SwingDemo(); JPanel panel = new JPanel(); String values[]= ...
Read MoreJava Program to set Selection Mode for JList only for single selection
To set single selection for JList, use DefaultListSelectionModel and set it to SINGLE_SELECTION:String values[]= { "One", "Two", "Three", "Four", "Five", "Six"}; JList list = new JList(values); list.setSelectionMode(DefaultListSelectionModel.SINGLE_SELECTION);The following is an example to set the selection mode for JList only for single selection:Examplepackage my; import java.awt.event.*; import java.awt.*; import javax.swing.*; class SwingDemo extends JFrame { static JFrame frame; static JList list; public static void main(String[] args) { frame = new JFrame("JList Demo"); SwingDemo s = new SwingDemo(); JPanel panel = new JPanel(); String values[]= { ...
Read MoreHow to store string array in Java JList?
To store string array in JList, at first create String array list:String sports[]= { "Football", "Fencing", "Cricket", "Squash", "Hockey", "Rugby"};Now, set it to JList:JList list = new JList(sports);The following is an example to store string array in JList:Examplepackage my; import java.awt.event.*; import java.awt.*; import javax.swing.*; class SwingDemo extends JFrame { static JFrame frame; static JList list; public static void main(String[] args) { frame = new JFrame("JList Demo"); SwingDemo s = new SwingDemo(); JPanel panel = new JPanel(); String sports[]= {"Football", "Fencing", "Cricket", "Squash", "Hockey", "Rugby"}; ...
Read MoreHow to add JList to Scroll pane in Java?
To add JList to Scroll pane in Java, use JScrollPane:JList list = new JList(sports); JScrollPane scrollPane = new JScrollPane(list);After that set it to Container:Container contentPane = frame.getContentPane(); contentPane.add(scrollPane, BorderLayout.CENTER);The following is an example to add JList to Scroll pane:Examplepackage my; import java.awt.event.*; import java.awt.*; import javax.swing.*; class SwingDemo extends JFrame { static JFrame frame; static JList list; public static void main(String[] args) { frame = new JFrame("JList Demo"); frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); String sports[]= {"Tennis", "Archery", "Football", "Fencing", "Cricket", "Squash", "Hockey", "Rugby"}; list = new JList(sports); ...
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