Java??????????????????

???????????? ???????[ 2013/8/12 10:43:23 ] ????????

????demo??PassObject.java

package javabase.flowcontrol;

class Letter{
char c;
}
public class PassObject {
/**
*????????
*/
static void f(Letter y){
y.c = 'z';
}
public static void main(String[] args) {
Letter x = new Letter();
x.c = 'a';
System.out.println("before:x.c = " + x.c);
f(x);
System.out.println("after:x.c = " + x.c);
}
}
/*????????
before:x.c = a
after:x.c = z
*/

?????????????????????????????????Think In Java??????”????????”

????????????????????

????++??--????++/--??????????????????++/--?????????????

????==??equals??

???????2???????????????????equals????????????????==

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????demo??EqualsTest.java

package javabase.flowcontrol;

class ValueInt{
int id;
}
class ValueString{
String id;
@Override
public boolean equals(Object obj) {
boolean instanceFlag;
instanceFlag = obj instanceof ValueString;
if(!instanceFlag)
   return super.equals(obj);
else{
   ValueString vTemp = (ValueString)obj;
   if(vTemp.id.equals(this.id)){
    return true;
   }
return false;
}
}
}
public class EqualsTest {
/**
* ==????????equals??????
*/
public static void main(String[] args) {
//????????????
int i1 = 100;
int i2 = 100;
System.out.println("i1 == i2 : " + (i1 == i2));
//????
Integer n1 = new Integer(250);
Integer n2 = new Integer(250);
System.out.println("n1 == n2 : " + (n1 == n2));
System.out.println("n1 equals n2 : " + n1.equals(n2));
//????????
ValueInt vInt1 = new ValueInt();
ValueInt vInt2 = new ValueInt();
vInt1.id = vInt2.id = 32;
System.out.println("vInt1 == vInt2 : " + (vInt1 == vInt2));
System.out.println("vInt1 equals vInt2 : " + vInt1.equals(vInt2));
ValueString vString1 = new ValueString();
ValueString vString2 = new ValueString();
vString1.id = vString2.id = "?????";
System.out.println("vString1 == vString2 : " + (vString1 == vString2));
System.out.println("vString1 equals vString2 : " + vString1.equals(vString2));
//String ?????????????????String????????????

}
}
/*????????
i1 == i2 : true
n1 == n2 : false
n1 equals n2 : true
vInt1 == vInt2 : false
vInt1 equals vInt2 : false //???????equals??????????2???????????
vString1 == vString2 : false
vString1 equals vString2 : true //??д??????equals?????????
*/