Example 17.5-1

class FinalFieldExample { 
    final int x;
    int y; 
    static FinalFieldExample f;

    public FinalFieldExample() {
        x = 3; 
        y = 4; 
    } 

    static void writer() {
        f = new FinalFieldExample();
    } 

    static void reader() {
        if (f != null) {
            int i = f.x;  // guaranteed to see 3  
            int j = f.y;  // could see 0
        } 
    } 
}

Example 17.5-1 version 2

class FinalFieldExample { 
    static HasFinalField f;

    static void writer() {
        f = new HasFinalField();
    } 

    static void reader() {
        if (f != null) {
            int i = f.x;  // guaranteed to see 3  
            int j = f.y;  // could see 0
        } 
    } 
}

class HasFinalField {
    final int x;
    int y; 

    public HasFinalField() {
        x = 3; 
        y = 4; 
    } 
}

Example 17.5-1 version 3

class FinalFieldExample { 
    HasFinalField f;

    void writer() {
        f = new HasFinalField();
    } 

    void reader() {
        if (f != null) {
            int i = f.x;  // guaranteed to see 3  
            int j = f.y;  // could see 0
        } 
    } 
}

class HasFinalField {
    final int x;
    int y; 

    public HasFinalField() {
        x = 3; 
        y = 4; 
    } 
}