Question

我正在阅读名为"Effective Java" by Joshua Bloch的书，并且有一段代码会导致内存泄漏。

public class Stack {
 private Object[] elements;
 private int size = 0;
 private static final int DEFAULT_INITIAL_CAPACITY = 16;

public Stack() {
    elements = new Object[DEFAULT_INITIAL_CAPACITY];
}

public void push(Object e) {
    ensureCapacity();
    elements[size++] = e;
}

public Object pop() {
    if (size == 0)
        throw new EmptyStackException();
    return elements[--size];
}

/**
 * Ensure space for at least one more element, roughly
 * doubling the capacity each time the array needs to grow.
 */
private void ensureCapacity() {
    if (elements.length == size)
        elements = Arrays.copyOf(elements, 2 * size + 1);
}

}

pop方法应替换为

public Object pop() {
    if (size == 0)
        throw new EmptyStackException();
    Object result = elements[--size];
    elements[size] = null; // Eliminate obsolete reference
    return result;
}

我很清楚。代码（见下文）会导致内存泄漏吗？例如，我旋转了很多次屏幕，private ArrayList<String> mArrayList = new ArrayList<String>(CAPASITY);每次都会分配内存。

public class MainActivity extends Activity implements OnClickListener {

    private static final int CAPASITY = 10000;
    private ArrayList<String> mArrayList = new ArrayList<String>(CAPASITY);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        // Some work on mArrayList
    }

    @Override
    public void onClick(View v) {
        // Some work on mArrayList
    }

    @Override
    protected void onDestroy() {
        super.onDestroy();
        // TODO: mArrayList = null to prevent memory leaks. Is it necessary to do it?
    }

}

Answer 1

// TODO：mArrayList = null以防止内存泄漏。有必要这样做吗？

不，活动对象及其成员（如mArrayList）可以进行垃圾回收。您的活动代码不会显示任何会不必要地保持对象引用的内容。

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1 个答案: