包装类类值传第
package study;import static org.junit.Assert.*;
import java.util.Arrays;
import java.util.Date;
import org.junit.Test;
public class test
{
@Test
public void test()
{
System.out.println(Math.sqrt(7.0));
}
@Test
public void testLong()
{
Long sum = 0L;
long start = System.currentTimeMillis();
for (long i = 0L; i < Integer.MAX_VALUE; i++)
{
sum += i;
}
long end = System.currentTimeMillis();
System.out.println("第一次执行耗时" + (end - start));
long sum2 = 0L;
long start2 = System.currentTimeMillis();
for (long i = 0L; i < Integer.MAX_VALUE; i++)
{
sum2 += i;
}
long end2 = System.currentTimeMillis();
System.out.println("第2次执行耗时" + (end2 - start2));
}
@Test
public void testMember()
{
Member m = new Member();
m.setId(12);
m.setName("qqqq");
Object m2 = new Object();
// clone();
}
@Test
public void testExchange()
{
String a = "aZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ";
String b = "bdd";
Exchange.exchangeString(a, b);
System.out.println(a);
System.out.println(b);
}
@Test
public void testInteger()
{
Integer a = new Integer(12);
Integer b = new Integer(129);
Exchange.exchangeInteger(a, b);
System.out.println(a);
System.out.println(b);
}
@Test
public void testDate()
{
Date a = new Date(System.currentTimeMillis() - 60 * 60 * 1000 * 7 * 24);
Date b = new Date();
Exchange.exchangeDate(a, b);
System.out.println(a);
System.out.println(b);
}
@Test
public void testExchangeArray()
{
String[] arr = new String[]{"qq","ww"};
Exchange.exchangeArray(arr);
System.out.println(Arrays.toString(arr));
}
//经过测试 Integer,String,Date,这些类也用的是值传递
}
package study;
import java.util.Date;
public class Exchange
{
public static void exchangeString(String a,String b)
{
String temp = a;
a = b;
b = temp;
}
public static void exchangeInteger(Integer a, Integer b)
{
Integer temp = a;
b = a;
a = temp;
}
public static void exchangeDate(Date a,Date b)
{
Date temp = a;
a = b;
b = temp;
}
public static void exchangeArray(String[] arr)
{
String temp = arr;
arr = arr;
arr = temp;
}
}
测试环境是ubuntukylin 14.04 x64 java1.8
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