Android大数据读取与折半查找（初步测试几毫秒）

主要实现了，100万条数据的内存读入，以及高效率的折半查找（折半查找大约几毫秒）

该项目分一个Activity和一个TestWrite类。

具体的看以下代码：

package com.example.androidtime;import gc.android.database.DataBase;import java.io.BufferedReader;import java.io.File;import java.io.FileInputStream;import java.util.Arrays;import android.annotation.SuppressLint;import android.app.Activity;import android.os.Bundle;import android.os.Environment;import android.os.Handler;import android.os.Message;import android.view.View;import android.widget.TextView;public class MainActivity extends Activity {public static DataBase db;private TextView tx;public static long[] arrays;static int i = 0;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);tx = (TextView) findViewById(R.id.tx);// db = new// DataBase(Environment.getExternalStorageDirectory().getPath(),// "/shorts.db");// db.openDataBase();new Thread(new Runnable() {@Overridepublic void run() {try {File shorts = new File(Environment.getExternalStorageDirectory().getPath()+ "/short.txt");arrays = new long[1000000];FileInputStream _in;_in = new FileInputStream(shorts);byte[] b = new byte[4000];while (_in.read(b) == 4000) {fillArrays(b);}_in.close();mhandler.sendMessage(mhandler.obtainMessage(0, "读取完成"));} catch (Exception e1) {}}}).start();}public void onclick(View v) {new Thread(new Runnable() {@Overridepublic void run() {// TODO 自动生成的方法存根// long _start = System.currentTimeMillis();// int _result = str.indexOf("2743097074l");// long _end = System.currentTimeMillis();// mhandler.sendMessage(mhandler.obtainMessage(0,// Arrays.toString(new long[] { _end - _start, _result })));try {mhandler.sendMessage(mhandler.obtainMessage(0,Arrays.toString(TestWrite.main())));} catch (Exception e) {mhandler.sendMessage(mhandler.obtainMessage(0, "err"));}}}).start();}private Handler mhandler = new Handler() {@Overridepublic void handleMessage(Message msg) {// TODO 自动生成的方法存根tx.setText(msg.obj.toString() + "\r\n" + tx.getText().toString());}};public static void fillArrays(byte[] b) {int _c = b.length / 10;for (int t = 0; t < _c; t++) {int _a = 10 * t;MainActivity.arrays[i] = Long.parseLong("" + b[0 + _a] + b[1 + _a]+ b[2 + _a] + b[3 + _a] + b[4 + _a] + b[5 + _a] + b[6 + _a]+ b[7 + _a] + b[8 + _a] + b[9 + _a]);i++;}}}

<pre name="code" class="java">package com.example.androidtime;import java.io.IOException;public class TestWrite {/* * 先按照数组为数据原型写出算法，再写出扩展性算法。数组{49,38,65,97,76,13,27} */public static void quickSort(int[] n, int left, int right) {int pivot;if (left < right) {// pivot作为枢轴，较之小的元素在左，较之大的元素在右pivot = partition(n, left, right);// 对左右数组递归调用快速排序，直到顺序完全正确quickSort(n, left, pivot - 1);quickSort(n, pivot + 1, right);}}public static int partition(int[] n, int left, int right) {int pivotkey = n[left];// 枢轴选定后永远不变，最终在中间，前小后大while (left < right) {while (left < right && n[right] >= pivotkey)--right;// 将比枢轴小的元素移到低端，此时right位相当于空，等待低位比pivotkey大的数补上n[left] = n[right];while (left < right && n[left] <= pivotkey)++left;// 将比枢轴大的元素移到高端，此时left位相当于空，等待高位比pivotkey小的数补上n[right] = n[left];}// 当left == right，完成一趟快速排序，此时left位相当于空，等待pivotkey补上n[left] = pivotkey;return left;}// 数据读取并转int// 导入数组public static long[] main() throws IOException, ClassNotFoundException {long _time = System.currentTimeMillis();// 2743097074lint index = splitHalf(MainActivity.arrays, 21826, 0,MainActivity.arrays.length - 1);long _time1 = System.currentTimeMillis();return new long[] { _time1, _time, index, MainActivity.arrays[index],MainActivity.arrays[0], MainActivity.arrays[999999] };}/** * 功 能：折半查找 *  * @param arrayData *            数组 * @param searchData *            要查找的数据 * @param start *            开始下标 * @param end *            结束下标 * @return 数据在数组中下标的位置，如果数据不在数组中，返回 -1 */public static int splitHalf(long[] arrayData, long searchData, int start,int end) {int index = (start + end) / 2;long data = arrayData[index];if (start > end) {return -1;}if (data == searchData) {return index;} else {if (data < searchData) {return splitHalf(arrayData, searchData, index + 1, end);} else {return splitHalf(arrayData, searchData, start, index - 1);}}}}

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