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/**
*
*/
package com.code;
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Arrays;
import java.util.Collections;
import junit.framework.Assert;
import org.junit.Test;
/**
* @author Chi
*
*/
public class FloatSelector {
// @Test
public void testGenerateData(){
this.generate(100000000);
}
@Test
public void select(){
long start = System.currentTimeMillis();
final int SIZE = 10000;
Float[] selected = new Float[SIZE];
BufferedInputStream in = new BufferedInputStream(this.getClass().getResourceAsStream("data"));
//Set buffer to load array for one time.
final int BUFFER_SIZE = SIZE * 4;
final byte[] buffer = new byte[BUFFER_SIZE];
//1, Fill selected array
int pointer = 0;
int read = 0;
try {
read = in.read(buffer);
for(int i = 0; i < read / 4; i++ ){
selected[pointer ++] = Float.intBitsToFloat(bytes2int(buffer, i*4));
}
//2, sort the array
Arrays.sort(selected, Collections.reverseOrder());
while((read = in.read(buffer)) > 0){
for(int i = 0; i < read / 4; i++ ){
float newValue = Float.intBitsToFloat(bytes2int(buffer, i*4));
int j;
for(j = selected.length - 1; j >= 0 && newValue > selected[j]; j--);
if(j < selected.length - 1){
//move
for(int k = selected.length - 1; k > j + 1; k --){
selected[k] = selected[k - 1];
}