java - 具有最终未初始化字段的抽象类

Question

我想知道下面的代码是否有意义，因为编译器警告说“空白的最终字段对象可能尚未初始化”。有更好的方法吗？

public abstract Test {
  protected final ArrayList<Object> objects;
}

public TestSubA extends Test {

  public TestSubA() {
    objects = new ArrayList<Objects>(20);
    // Other stuff
  }
}

public TestSubB extends Test {

  public TestSubB() {
    objects = new ArrayList<Objects>(100);
    // Other stuff
  }
}

Answer 1

我会将字段设为 final 并强制构造函数向上传递值:

public abstract class Test {
  private final ArrayList<Object> objects;

  protected ArrayList<Object> getObjects() {
    return objects;
  }

  protected Test(ArrayList<Object> objects) {
    this.objects = objects;
  }
}

public class TestSubA extends Test {

  public TestSubA() {
    super(new ArrayList<Object>(20));
    // Other stuff
  }
}

public class TestSubB extends Test {

  public TestSubB() {
    super(new ArrayList<Object>(100));
    // Other stuff
  }
}