Java: What is the difference between final, finally, and finalize?

1final int MAX = 100;
2// MAX = 200; // COMPILE ERROR
3
4final List<String> list = new ArrayList<>();
5list.add("item");        // OK — modify object
6// list = new ArrayList<>(); // COMPILE ERROR — reassign

1class Parent {
2    final void important() { System.out.println("Locked method"); }
3}
4class Child extends Parent {
5    // void important() { } // COMPILE ERROR
6}

1final class Immutable {
2    private final int value;
3    Immutable(int v) { this.value = v; }
4}
5// class Sub extends Immutable { } // COMPILE ERROR

1FileInputStream fis = null;
2try {
3    fis = new FileInputStream("data.txt");
4} catch (FileNotFoundException e) {
5    System.err.println("Not found");
6} finally {
7    if (fis != null) try { fis.close(); } catch (IOException e) { }
8    System.out.println("Cleanup done");
9}
10
11// Better: try-with-resources
12try (FileInputStream fis2 = new FileInputStream("data.txt")) {
13    // use file...
14} catch (IOException e) {
15    System.err.println("Error");
16}
17// fis2 closed automatically

1// BAD: old approach
2class OldResource {
3    @Override
4    protected void finalize() throws Throwable {
5        try { /* cleanup */ } finally { super.finalize(); }
6    }
7}
8
9// GOOD: modern approach
10class ModernResource implements AutoCloseable {
11    @Override
12    public void close() {
13        System.out.println("Closed deterministically");
14    }
15}
16try (ModernResource r = new ModernResource()) {
17    // use resource...
18} // close() called immediately