Android应用性能优化之使用SparseArray

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。

一，我们来看看SparseArray点击进去包含了那些方法：

//
// 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!");
}
}

二，增加

public void put(int key, E value) {
throw new RuntimeException("Stub!");
}
public void append(int key, E value) {
throw new RuntimeException("Stub!");
}

通过键值对方式存储。

三，删除

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!");
}

delete，remove根据key来删除，removeAt根据下标删除，removeAtRange根据下标范围删除。

四，改变

public void setValueAt(int index, E value) {
throw new RuntimeException("Stub!");
}
public void put(int key, E value) {
throw new RuntimeException("Stub!");
}

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。

五，查找

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!");
}

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。

构造方法：

public SparseArray(int initialCapacity) {
throw new RuntimeException("Stub!");
}

可以初始化长度，SparseArray array=new SparseArray<>(5);

SparseIntArray intArray=new SparseIntArray();
SparseBooleanArray booleanArray=new SparseBooleanArray();
SparseLongArray longArray=new SparseLongArray();

来取代相应的HashMap