Android应用性能优化之使用SparseArray
ig1032
8年前
<p>最近在看一些Android应用性能优化的文章时，发现提到了SparseArray替代HashMap可以优化app性能，就对SparseArray做了一番了解，并记录使用心得。</p> <h2><strong>我们来看看SparseArray点击进去包含了那些方法</strong></h2> <pre> <code class="language-java">// // Source code recreated from a .class file by IntelliJ IDEA // (powered by Fernflower decompiler) // package android.util; public class SparseArray<E> implements Cloneable { public SparseArray() { throw new RuntimeException("Stub!"); } public SparseArray(int initialCapacity) { throw new RuntimeException("Stub!"); } public SparseArray<E> clone() { throw new RuntimeException("Stub!"); } public E get(int key) { throw new RuntimeException("Stub!"); } public E get(int key, E valueIfKeyNotFound) { throw new RuntimeException("Stub!"); } public void delete(int key) { throw new RuntimeException("Stub!"); } public void remove(int key) { throw new RuntimeException("Stub!"); } public void removeAt(int index) { throw new RuntimeException("Stub!"); } public void removeAtRange(int index, int size) { throw new RuntimeException("Stub!"); } public void put(int key, E value) { throw new RuntimeException("Stub!"); } public int size() { throw new RuntimeException("Stub!"); } public int keyAt(int index) { throw new RuntimeException("Stub!"); } public E valueAt(int index) { throw new RuntimeException("Stub!"); } public void setValueAt(int index, E value) { throw new RuntimeException("Stub!"); } public int indexOfKey(int key) { throw new RuntimeException("Stub!"); } public int indexOfValue(E value) { throw new RuntimeException("Stub!"); } public void clear() { throw new RuntimeException("Stub!"); } public void append(int key, E value) { throw new RuntimeException("Stub!"); } public String toString() { throw new RuntimeException("Stub!"); } } </code></pre> <h2><strong>增加</strong></h2> <pre> <code class="language-java"> public void put(int key, E value) { throw new RuntimeException("Stub!"); } public void append(int key, E value) { throw new RuntimeException("Stub!"); }</code></pre> <p>通过键值对方式存储。</p> <h2><strong>删除</strong></h2> <pre> <code class="language-java"> public void delete(int key) { throw new RuntimeException("Stub!"); } public void remove(int key) { throw new RuntimeException("Stub!"); } public void removeAt(int index) { throw new RuntimeException("Stub!"); } public void removeAtRange(int index, int size) { throw new RuntimeException("Stub!"); } public void clear() { throw new RuntimeException("Stub!"); }</code></pre> <p>delete，remove根据key来删除，removeAt根据下标删除，removeAtRange根据下标范围删除。</p> <h2><strong>改变</strong></h2> <pre> <code class="language-java"> public void setValueAt(int index, E value) { throw new RuntimeException("Stub!"); } public void put(int key, E value) { throw new RuntimeException("Stub!"); }</code></pre> <p>setValueAt根据下标来重新赋值，put通过key来重新赋值，有就重新赋值，没有就添加。</p> <h2><strong>查找</strong></h2> <pre> <code class="language-java"> public E get(int key) { throw new RuntimeException("Stub!"); } //设置没有查找到的返回信息 public E get(int key, E valueIfKeyNotFound) { throw new RuntimeException("Stub!"); } public int keyAt(int index) { throw new RuntimeException("Stub!"); } public E valueAt(int index) { throw new RuntimeException("Stub!"); } public int indexOfKey(int key) { throw new RuntimeException("Stub!"); } public int indexOfValue(E value) { throw new RuntimeException("Stub!"); } </code></pre> <p>get根据key来查找。keyAt根据下标查找key值，valueAt通过下标查找value，indexOfKey通过key查询下标，indexOfValue通过value查找下标。</p> <h2><strong>构造方法</strong></h2> <pre> <code class="language-java"> public SparseArray(int initialCapacity) { throw new RuntimeException("Stub!"); }</code></pre> <p>可以初始化长度，SparseArray array=new SparseArray<>(5);</p> <pre> <code class="language-java">SparseIntArray intArray=new SparseIntArray(); SparseBooleanArray booleanArray=new SparseBooleanArray(); SparseLongArray longArray=new SparseLongArray();</code></pre> <p>来取代相应的HashMap</p> <p> </p> <p>来自： <a href="/misc/goto?guid=4959675051591855644" rel="nofollow">http://blog.csdn.net/qq_16131393/article/details/51821210</a></p> <p> </p>