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public class MemoryExp {
public static void main(String[] args) {
System.out.println("Total Memory"+Runtime.getRuntime().totalMemory());
System.out.println("Free Memory"+Runtime.getRuntime().freeMemory());
}
}
2. ÈçºÎдһ¸ö²»ÐèÒªmain·½·¨µÄjavaÓ¦ÓóÌÐò£¿
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class MainMethodNot
{
static
{
System.out.println("This java program have run without the run method");
System.exit(0);
}
}
3. Çë˵³öÉÏÀýÖеĴúÂëΪʲô¿ÉÒÔÔËÐУ¿
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4.½éÉÜÒ»ÏÂJavaµÄMapÒÔ¼°ÈçºÎʹÓÃHashMap£¿
MapÊÇÒ»¸ö±£´æ¼üÖµ¶ÔµÄ¶ÔÏ󣬸ù¾Ý¼üÖµ¿ÉÒÔÕÒµ½Ëü¶ÔÓ¦µÄÖµ¡£¼ü±ØÐëÊÇΨһµÄ£¬µ«ÊÇÖµ¿ÉÒÔÖØ¸´¡£HashMapÀàÌṩÁËmap½Ó¿ÚµÄÖ÷ҪʵÏÖ£¬ËüʹÓÃhash tableÀ´ÊµÏÖmap½Ó¿Ú¡£Õâ¾ÍʹµÃһЩ³£¼ûµÄ²Ù×÷Èçget()ºÍput()ËùÓõÄʱ¼ä»ù±¾²»±ä¡£
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import java.util.*;
public class HashMapDemo {
public static void main( String[] args) {
HashMap hm = new HashMap();
hm.put(“Rohit”, new Double(3434.34));
hm.put(“Mohit”, new Double(123.22));
hm.put(“Ashish”, new Double(1200.34));
hm.put(“Khariwal”, new Double(99.34));
hm.put(“Pankaj”, new Double(-19.34));
Set set = hm.entrySet();
Iterator i = set.iterator();
while(i.hasNext()){
Map.Entry me = (Map.Entry)i.next();
System.out.println(me.getKey() + “ : ” + me.getValue() );
}
//deposit into Rohit’s Account
double balance = ((Do
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import java.util.regex.Matcher;
import java.util.regex.Pattern;
public class StringUtil {
public static void replaceBlank()
{
Pattern p = Pattern.compile("\\s*|\t|\r|\n");
String str="I am a, I am Hello ok, \n new line ffdsa!";
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