Java基础：数据类型

数据类型作参数：

eg1:

class Test03

{

public static void main(String[] args)

{

StringBuffer s= new StringBuffer("good");

StringBuffer s2=new StringBuffer("bad");

test(s,s2);

System.out.println(s);//9

System.out.println(s2);//10

}

static void test(StringBuffer s,StringBuffer s2) {

System.out.println(s);//1

System.out.println(s2);//2

s2=s;//3

s=new StringBuffer("new");//4

System.out.println(s);//5

System.out.println(s2);//6

s.append("hah");//7

s2.append("hah");//8

}

}

---

publicString change(String s){

s ="222";

returns;

}

publicstaticvoidmain(Stirng[] args){

String s ="111";

change(s);

sout(s);

}

---

class Test02

{

public static void main(String[] args)

{

int i=5;

int i2=i;

i2=6;

System.out.println(i);

}

}

程序的结果是什么？5！！！

这说明什么，原始数据类型是按值传递的，这个按值传递也是指的是进行赋值时的行为下一个问题：Java 应用程序有且仅有的一种参数传递机制，即按值传递

---

publicString change(String s,inti, StringBuffer sb, Person p){

s="123";

i=3;

sb.append("woshi");

p.setAge(100);

sb =newStringBuffer("sbsb");

p =newPerson("bb",44);

returns;

}

@Test

publicvoidtestChange(){

StringBuffer sb =newStringBuffer("buff");

String s ="aaa";

inti =1;

Person p =newPerson("aa",12);

i=2;

change(s,i,sb,p);

//        s="222";

System.out.println(s);

System.out.println(i);

System.out.println(sb.toString());

System.out.println(p);

}