Java Collections - ArrayList.trimToSize() Examples

package com.logicbig.example.arraylist;

import java.util.*;

public class TrimToSizeExample {

    public static void main(String... args) {
        // Trim capacity to current size to save memory
        ArrayList<String> list = new ArrayList<>(100);
        list.add("One");
        list.add("Two");
        System.out.println("Before trim - Size: " + list.size());
        list.trimToSize();
        System.out.println("After trim - Size still: " + list.size());
    }
}

package com.logicbig.example.arraylist;

import java.util.*;

public class TrimToSizeExample2 {

    public static void main(String... args) {
        // After removing many elements, trim to save space
        ArrayList<Integer> numbers = new ArrayList<>(1000);
        for(int i = 0; i < 1000; i++) numbers.add(i);
        numbers.removeIf(n -> n % 2 == 0); // Remove even numbers
        System.out.println("After removal - Size: " + numbers.size());
        numbers.trimToSize();
        System.out.println("After trim - Memory optimized");
    }
}