/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* @author Administrator
*/
public class 測試代碼2 {
public static void main(String args[]) {
int intSize = 0;
try {
//for (int i = 191059999; i <= 191160000; i++) {
//內存開到3個g可以跑4開頭的9位數int
for (int i = 447483646; i <= 2147483647; i++) {
intSize = i;
int[] allInt = new int[i];
System.out.println("allInt:" + allInt.length);
}
} catch (Exception e) {
} finally {
System.out.println("intSize:" + intSize);
}
}
}
import java.util.ArrayList;
/*
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* and open the template in the editor.
*/
/**
*
* @author Administrator
*/
public class 測試代碼1 {
static ArrayList<Integer> dataList = new ArrayList<Integer>();
public static void main(String args[]) {
int judgeListmaxCount = 0;
try {
for (int i = 0; i <= 500000000; i++) {
judgeListmaxCount = i;
dataList.add(i);
}
} catch (Exception e) {
System.out.println("judgeListmaxCount:" + judgeListmaxCount);
} finally {
System.out.println("judgeListmaxCount:" + judgeListmaxCount);
}
}
}
java代碼測試集合,數組等最大存儲大小
分類: java常用知識
2011-11-21 19:00 305人閱讀 評論(0) 收藏 舉報
其實java裏面的集合,數組等他們的存儲容量我們是可以預估的。1、存儲原始類型,這種存儲大小是固定的。2、存儲對象,由於內容大小有變化,但是我們可以通過測試獲取到大慨存儲容量。
還有就是我們擴容內存,會影響集合或數組存儲大小。
1、List<Integer>
int judgeListmaxCount = 0;
try {
for (int i = 0; i <= 50000000; i++) {
judgeListmaxCount = i;
dataList.add(i);
}
} catch (Exception e) {
System.out.println("judgeListmaxCount:" + judgeListmaxCount);
} finally {
System.out.println("judgeListmaxCount:" + judgeListmaxCount);
}
異常消息:
Exception in thread "main" judgeListmaxCount:38647475
java.lang.OutOfMemoryError: Java heap space
at java.util.ArrayList.ensureCapacity(ArrayList.java:169)
at java.util.ArrayList.add(ArrayList.java:351)
at com.yxie.test.CreateDichotoSearchData.main(CreateDichotoSearchData.java:21)
xieyun@xieyun-OptiPlex-760:~/work/dichotomy/bin$ java -Xms1024m -Xmx1024m com.yxie.test.CreateDichotoSearchData
judgeListmaxCount:38647475
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at java.util.Arrays.copyOf(Arrays.java:2760)
at java.util.Arrays.copyOf(Arrays.java:2734)
at java.util.ArrayList.ensureCapacity(ArrayList.java:167)
at java.util.ArrayList.add(ArrayList.java:351)
at com.yxie.test.CreateDichotoSearchData.main(CreateDichotoSearchData.java:21)
2、int[]
int intSize = 0;
try {
for (int i = 191059999; i <= 191160000; i++) {
intSize = i;
int[] allInt = new int[i];
System.out.println("allInt:" + allInt.length);
}
} catch (Exception e) {
} finally {
System.out.println("intSize:" + intSize);
}
異常消息:
intSize:191060000
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at com.yxie.test.CreateDichotoSearchData.main(CreateDichotoSearchData.java:54)
改變java虛擬機內存大小,會影響int[]數組大小。
xieyun@xieyun-OptiPlex-760:~/work/dichotomy/bin$ java -Xms1024m -Xmx1024m com.yxie.test.CreateDichotoSearchData
Integer max:2147483647
fileSize:4000000000
spareFileSize:1852516353
intSize:191059999
Exception in thread "main" java.lang.OutOfMemoryError: Java heap space
at com.yxie.test.CreateDichotoSearchData.main(CreateDichotoSearchData.java:54)
xieyun@xieyun-OptiPlex-760:~/work/dichotomy/bin$
xieyun@xieyun-OptiPlex-760:~/work/dichotomy/bin$ java -Xms2024m -Xmx2024m com.yxie.test.CreateDichotoSearchData
Integer max:2147483647
fileSize:4000000000
spareFileSize:1852516353
allInt:191059999
allInt:191060000
allInt:191060001
import java.util.HashMap;
/*
* To change this template, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* @author Administrator
*/
public class hashmap {
static HashMap<Integer, Integer> dataList = new HashMap<Integer, Integer>();
public static void main(String args[]) {
int judgeListmaxCount = 0;
try {
for(int j=0;j<1000;j++){
//447483646
//小於300*225000時效率較高
for (int i = 0; i <= 225000; i++) {
judgeListmaxCount ++;
dataList.put(i*j+i, i*j);}
System.out.println(j);
}
} catch (Exception e) {
System.out.println("judgeListmaxCount:" + judgeListmaxCount);
} finally {
System.out.println("judgeListmaxCount:" + judgeListmaxCount);
}
}
}