Java TreeMap Comparator

Author: JavaProgramTo.com

src/main/java/com/javaprogramto/collections/treemap/comparator/TreeMapComparatorByValueExample.java

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+package com.javaprogramto.collections.treemap.comparator;
+
+import java.util.Comparator;
+import java.util.Map;
+import java.util.SortedSet;
+import java.util.TreeMap;
+import java.util.TreeSet;
+
+public class TreeMapComparatorByValueExample {
+
+	public static void main(String[] args) {
+
+		SortedSet<Map.Entry<Customer, Integer>> sortedset = new TreeSet<>(
+				new Comparator<Map.Entry<Customer, Integer>>() {
+					@Override
+					public int compare(Map.Entry<Customer, Integer> e1, Map.Entry<Customer, Integer> e2) {
+						return e1.getValue().compareTo(e2.getValue());
+					}
+				});
+
+		Map<Customer, Integer> customerAgeMap = new TreeMap<>(Comparator.comparing(Customer::getId));
+
+		customerAgeMap.put(new Customer(123, "D"), 30);
+		customerAgeMap.put(new Customer(102, "B"), 70);
+		customerAgeMap.put(new Customer(135, "A"), 40);
+		customerAgeMap.put(new Customer(130, "C"), 50);
+
+		sortedset.addAll(customerAgeMap.entrySet());
+
+		System.out.println("java 8 - treemap sort by value - " + sortedset);
+
+	}
+}

src/main/java/com/javaprogramto/collections/treemap/comparator/TreeMapComparatorCustomObjectsExample.java

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+package com.javaprogramto.collections.treemap.comparator;
+
+import java.util.Map;
+import java.util.TreeMap;
+
+public class TreeMapComparatorCustomObjectsExample {
+
+	public static void main(String[] args) {
+
+		Map<Customer, Integer> customerAgeMap = new TreeMap<>();
+
+		customerAgeMap.put(new Customer(123, "D"), 30);
+		customerAgeMap.put(new Customer(102, "B"), 70);
+		customerAgeMap.put(new Customer(135, "A"), 40);
+		customerAgeMap.put(new Customer(130, "C"), 50);
+
+		System.out.println("treemap - " + customerAgeMap);
+		
+		
+
+	}
+}
+
+class Customer {
+	private int id;
+	private String name;
+
+	public Customer(int id, String name) {
+		super();
+		this.id = id;
+		this.name = name;
+	}
+
+	public int getId() {
+		return id;
+	}
+
+	public void setId(int id) {
+		this.id = id;
+	}
+
+	public String getName() {
+		return name;
+	}
+
+	public void setName(String name) {
+		this.name = name;
+	}
+
+	@Override
+	public String toString() {
+		return "Customer [id=" + id + ", name=" + name + "]";
+	}
+}

src/main/java/com/javaprogramto/collections/treemap/comparator/TreeMapComparatorCustomObjectsExample2.java

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+package com.javaprogramto.collections.treemap.comparator;
+
+import java.util.Comparator;
+import java.util.Map;
+import java.util.TreeMap;
+
+public class TreeMapComparatorCustomObjectsExample2 {
+
+	public static void main(String[] args) {
+
+		Map<Customer, Integer> customerAgeMap = new TreeMap<>(new Comparator<Customer>() {
+			@Override
+			public int compare(Customer o1, Customer o2) {
+				Integer id1 = o1.getId();
+				Integer id2 = o2.getId();
+				return id1.compareTo(id2);
+			}
+		});
+
+		customerAgeMap.put(new Customer(123, "D"), 30);
+		customerAgeMap.put(new Customer(102, "B"), 70);
+		customerAgeMap.put(new Customer(135, "A"), 40);
+		customerAgeMap.put(new Customer(130, "C"), 50);
+
+		System.out.println("treemap with comparator - " + customerAgeMap);
+
+	}
+}

src/main/java/com/javaprogramto/collections/treemap/comparator/TreeMapComparatorCustomObjectsExample3.java

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+package com.javaprogramto.collections.treemap.comparator;
+
+import java.util.Comparator;
+import java.util.Map;
+import java.util.TreeMap;
+
+public class TreeMapComparatorCustomObjectsExample3 {
+
+	public static void main(String[] args) {
+
+		Map<Customer, Integer> customerAgeMap = new TreeMap<>(new Comparator<Customer>() {
+			@Override
+			public int compare(Customer o1, Customer o2) {
+				String name1 = o1.getName();
+				String name2 = o2.getName();
+				
+				return name1.compareTo(name2);
+			}
+		});
+
+		customerAgeMap.put(new Customer(123, "D"), 30);
+		customerAgeMap.put(new Customer(102, "B"), 70);
+		customerAgeMap.put(new Customer(135, "A"), 40);
+		customerAgeMap.put(new Customer(130, "C"), 50);
+
+		System.out.println("treemap - " + customerAgeMap);
+
+	}
+}

src/main/java/com/javaprogramto/collections/treemap/comparator/TreeMapComparatorCustomObjectsExample4.java

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+package com.javaprogramto.collections.treemap.comparator;
+
+import java.util.Comparator;
+import java.util.Map;
+import java.util.TreeMap;
+
+public class TreeMapComparatorCustomObjectsExample4 {
+
+	public static void main(String[] args) {
+
+		Map<Customer, Integer> customerAgeMap = new TreeMap<>(Comparator.comparing(Customer::getId));
+
+		customerAgeMap.put(new Customer(123, "D"), 30);
+		customerAgeMap.put(new Customer(102, "B"), 70);
+		customerAgeMap.put(new Customer(135, "A"), 40);
+		customerAgeMap.put(new Customer(130, "C"), 50);
+
+		System.out.println("java 8 - treemap sort by id - " + customerAgeMap);
+		
+		Map<Customer, Integer> customerAgeMap2 = new TreeMap<>(Comparator.comparing(Customer::getName));
+
+		customerAgeMap2.put(new Customer(123, "D"), 30);
+		customerAgeMap2.put(new Customer(102, "B"), 70);
+		customerAgeMap2.put(new Customer(135, "A"), 40);
+		customerAgeMap2.put(new Customer(130, "C"), 50);
+
+		System.out.println("java 8 - treemap sort by name - " + customerAgeMap2);
+
+	}
+}

src/main/java/com/javaprogramto/collections/treemap/comparator/TreeMapComparatorExample.java

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+package com.javaprogramto.collections.treemap.comparator;
+
+import java.util.Map;
+import java.util.TreeMap;
+
+public class TreeMapComparatorExample {
+
+	public static void main(String[] args) {
+
+		Map<String, Integer> designationSalaryInUSD = new TreeMap<>();
+
+		designationSalaryInUSD.put("Software Engineer", 150_000);
+		designationSalaryInUSD.put("Senior Software Engineer", 210_000);
+		designationSalaryInUSD.put("Manger", 300_000);
+		designationSalaryInUSD.put("Lead Engineer", 250_000);
+
+		System.out.println("treemap - " + designationSalaryInUSD);
+	}
+}