Java Container Capacity
¶
capacity 공
~cpp StringBuffer , Vector . 겠.결과 ¶
capacity
~cpp Show String Buffer capactity by Data I/O in increment data length: 0 capacity: 16 data length: 17 capacity: 34 <-- 길 data length: 35 capacity: 70 data length: 71 capacity: 142 data length: 143 capacity: 286 data length: 287 capacity: 574 data length: 575 capacity: 1,150 data length: 1,151 capacity: 2,302 data length: 2,303 capacity: 4,606 data length: 4,607 capacity: 9,214 data length: 9,215 capacity: 18,430 data length: 18,431 capacity: 36,862 data length: 36,863 capacity: 73,726 data length: 73,727 capacity: 147,454 data length: 147,455 capacity: 294,910 data length: 294,911 capacity: 589,822 data length: 589,823 capacity: 1,179,646 data length: 1,000,000 capacity: 1,179,646 <-- . Show String Buffer capactity by Data I/O in decrement data length: 1,000,000 capacity: 1,179,646 data length: 0 capacity: 1,179,646 <-- Show Vector capactity by Data I/O in increment data length: 0 capacity: 10 data length: 11 capacity: 20 <-- capacity data length: 21 capacity: 40 data length: 41 capacity: 80 data length: 81 capacity: 160 data length: 161 capacity: 320 data length: 321 capacity: 640 data length: 641 capacity: 1,280 data length: 1,281 capacity: 2,560 data length: 2,561 capacity: 5,120 data length: 5,121 capacity: 10,240 data length: 10,241 capacity: 20,480 data length: 20,481 capacity: 40,960 data length: 40,961 capacity: 81,920 data length: 81,921 capacity: 163,840 data length: 163,841 capacity: 327,680 data length: 327,681 capacity: 655,360 data length: 655,361 capacity: 1,310,720 data length: 1,000,000 capacity: 1,310,720 <-- . Show String Buffer capactity by Data I/O in decrement data length: 1,000,000 capacity: 1,310,720 data length: 0 capacity: 1,310,720 <--
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;; 간 .
~cpp
import java.io.PrintStream;
import java.io.PrintWriter;
import java.text.DecimalFormat;
import java.util.Vector;
public class CapacityTest {
private static final int NUMBER_LIMIT_LEN = 10;
private PrintStream out;
private PrintWriter k;
private int totalNumOfData = 1000000;
public static void main(String[] args) {
CapacityTest capacity = new CapacityTest(System.out);
capacity.testStringBuffer();
capacity.testVector();
}
public CapacityTest(PrintStream anOut) {
out = anOut;
if (out == null)
throw new NullPointerException("out is null");
}
public void testStringBuffer() {
StringBuffer stringBuffer = new StringBuffer();
showStringBufferIncrease(stringBuffer);
showStringBufferDecrease(stringBuffer);
}
public void testVector() {
Vector vector = new Vector();
showVectorIncrease(vector);
showVectorDecrease(vector);
}
private void printTitle(String aContainerKind, String aSituation) {
out.println();
out.println(
"Show "
+ aContainerKind
+ " capactity by Data I/O in "
+ aSituation);
}
private void printContainerState(int aSize, int aCapacity) {
DecimalFormat df = new DecimalFormat("###,###,###");
String size = df.format(aSize);
String capacity = df.format(aCapacity);
size = getShowedString(size, NUMBER_LIMIT_LEN);
capacity = getShowedString(capacity, NUMBER_LIMIT_LEN);
out.println("data length:" + size + "\tcapacity:" + capacity);
}
private String getShowedString(String aSrc, int aLimit) {
int insufficientLen = aLimit - aSrc.length();
StringBuffer showedString = new StringBuffer(aLimit);
for (int i = 0; i < insufficientLen; i++)
showedString.append(" ");
showedString.append(aSrc);
return showedString.toString();
}
public void showStringBufferIncrease(StringBuffer stringBuffer) {
printTitle("String Buffer", "increment");
printContainerState(stringBuffer.length(), stringBuffer.capacity());
for (int length = 0; length < totalNumOfData; length++) {
int oldCapacity = stringBuffer.capacity();
stringBuffer.append((char) ('a' + length % 26));
if (oldCapacity != stringBuffer.capacity())
printContainerState(
stringBuffer.length(),
stringBuffer.capacity());
}
printContainerState(stringBuffer.length(), stringBuffer.capacity());
}
public void showStringBufferDecrease(StringBuffer stringBuffer) {
printTitle("String Buffer", "decrement");
printContainerState(stringBuffer.length(), stringBuffer.capacity());
for (int counter = stringBuffer.length(); counter > 0; counter--) {
int oldCapacity = stringBuffer.capacity();
stringBuffer.delete(
stringBuffer.length() - 1,
stringBuffer.length());
if (oldCapacity != stringBuffer.capacity())
printContainerState(
stringBuffer.length(),
stringBuffer.capacity());
}
printContainerState(stringBuffer.length(), stringBuffer.capacity());
}
public void showVectorIncrease(Vector aVector) {
printTitle("Vector", "increment");
printContainerState(aVector.size(), aVector.capacity());
for (int size = 0; size < totalNumOfData; size++) {
int oldCapacity = aVector.capacity();
aVector.add("This is Gabage Data");
if (oldCapacity != aVector.capacity())
printContainerState(aVector.size(), aVector.capacity());
}
printContainerState(aVector.size(), aVector.capacity());
}
public void showVectorDecrease(Vector aVector) {
printTitle("String Buffer", "decrement");
printContainerState(aVector.size(), aVector.capacity());
for (int counter = aVector.size(); counter > 0; counter--) {
int oldCapacity = aVector.capacity();
aVector.remove(aVector.size() - 1);
if (oldCapacity != aVector.capacity())
printContainerState(aVector.size(), aVector.capacity());
}
printContainerState(aVector.size(), aVector.capacity());
}
}
