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Stack.java
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36 lines (30 loc) · 817 Bytes
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// Can you spot the "memory leak"?
package effectivejava.chapter2;
import java.util.Arrays;
import java.util.EmptyStackException;
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();
// 上面的过期已用没有清除，所以会发生内存泄露
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);
}
}