Java 对象数组 泛型类

Data Structures and Algorithm Analysis in Java (Second Edition) Reading Notes Series

Function Class:

package com.itechzero.test;

/**
 * ObjectCollection.java
 *
 * @author Techzero
 * @Email techzero@163.com
 * @Time 2014年10月26日 下午6:15:16
 */
public class ObjectCollection {
	/**
	 * The array is used to store objects.
	 */
	private Object storedValue[] = null;

	/**
	 * isEmpty() is used to judge whether the collection is empty.
	 */
	public boolean isEmpty() {
		return storedValue == null ? true : false;
	}

	/**
	 * makeEmpty() is used to empty the collection.
	 */
	public void makeEmpty() {
		storedValue = null;
	}

	/**
	 * insert(Object x) is used to insert an object into the collection.
	 * 
	 * @param x
	 *            The object to insert into the collection.
	 */
	public void insert(Object x) {
		storedValue = storedValue == null ? new Object[1] : new Object[storedValue.length + 1];
		storedValue[storedValue.length - 1] = x;
	}

	/**
	 * remove(Object x) is used to remove an object from the collection.
	 * 
	 * @param x
	 *            The object to remove from the collection.
	 */
	public void remove(Object x) {
		if (storedValue != null) {
			if (storedValue.length == 1) {
				storedValue = null;
				return;
			}
			int pos = -1;
			for (int i = 0; i < storedValue.length; i++) {
				if (storedValue[i].equals(x)) {
					storedValue[i] = null;
					pos = i;
					break;
				}
			}
			if (pos != -1) {
				Object temp[] = storedValue;
				storedValue = new Object[storedValue.length - 1];
				for (int i = 0; i < temp.length; i++) {
					if (i < pos) {
						storedValue[i] = temp[i];
					} else if (i == pos) {
						continue;
					} else {
						storedValue[i - 1] = temp[i];
					}
				}
			}
		}
	}

	/**
	 * isPresent(Object x) is used to judge whether an object is in the collection.
	 * 
	 * @param x
	 *            The object to judge.
	 */
	public boolean isPresent(Object x) {
		int pos = -1;
		if (storedValue != null) {
			for (int i = 0; i < storedValue.length; i++) {
				if (storedValue[i].equals(x)) {
					storedValue[i] = null;
					pos = i;
					break;
				}
			}
		}
		return pos == -1 ? false : true;
	}
}

Test Class:

package com.itechzero.test;

/**
 * ObjectCollectionTest.java
 *
 * @author Techzero
 * @Email techzero@163.com
 * @Time 2014年10月26日 下午6:26:48
 */
public class ObjectCollectionTest {
	public static void main(String[] args) {
		ObjectCollection collection = new ObjectCollection();
		System.out.println("collection.isEmpty(): " + collection.isEmpty());
		collection.insert(123);
		System.out.println("collection.isEmpty(): " + collection.isEmpty());
		collection.remove(123);
		System.out.println("collection.isEmpty(): " + collection.isEmpty());
		collection.insert(123);
		System.out.println("collection.isEmpty(): " + collection.isEmpty());
		System.out.println("collection.isPresent(123): " + collection.isPresent(123));
		collection.makeEmpty();
		System.out.println("collection.isEmpty(): " + collection.isEmpty());
		System.out.println("collection.isPresent(123): " + collection.isPresent(123));
	}
}

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