匿名对象、单例模式饿汉式、自动生成对象args[]数组使用、静态关键字
package
practice;
class
Person {
private
String name;
private
static
int
count;
public
Person(){
count++;
this
.name=
"NONAME - "
+ count;
}
public
Person(String name){
this
.name=name;
}
public
String getInfo(){
return
"姓名:"
+
this
.name;
}
}
public
class
DemoOutput {
public
static
void
main(String args[]) {
System.out.println(
new
Person().getInfo());
System.out.println(
new
Person(
"A"
).getInfo());
System.out.println(
new
Person(
"B"
).getInfo());
System.out.println(
new
Person().getInfo());
}
};
package
practice;
class
Person1{
private
String name;
private
static
int
count;
public
Person1(){
count++;
System.out.println(
"产生了"
+count+
"个实例化对象。"
);
}
public
String getInfo(){
return
"姓名:"
+
this
.name;
}
};
public
class
DemoOutputA {
public
static
void
main(String args[]){
new
Person1();
new
Person1();
new
Person1();
new
Person1();
new
Person1();
}
};
package
practice;
class
Person2{
private
String name;
private
int
age;
static
String city=
"A城"
;
public
Person2(String name,
int
age){
this
.name=name;
this
.age=age;
}
public
String getInfo(){
return
"姓名:"
+
this
.name+
",年龄:"
+
this
.age+
",城市:"
+city;
}
};
public
class
DemoOutputB {
public
static
void
main(String args[]){
Person2 per1=
new
Person2(
"张三"
,
30
);
Person2 per2=
new
Person2(
"李四"
,
31
);
Person2 per3=
new
Person2(
"王五"
,
30
);
System.out.println(
"==========信息修改之前=========="
);
System.out.println(per1.getInfo());
System.out.println(per2.getInfo());
System.out.println(per3.getInfo());
System.out.println(
"==========信息修改之前=========="
);
Person2.city=
"B城"
;
System.out.println(per1.getInfo());
System.out.println(per2.getInfo());
System.out.println(per3.getInfo());
}
};
package
practice;
class
Single{
private
static
Single instance=
new
Single();
private
Single(){
//将构造方法私有化
}
public
static
Single getInstance(){
return
instance;
}
public
void
print(){
System.out.println(
"hello world!!!"
);
}
};
public
class
DemoOutputC {
public
static
void
main(String args[]){
Single s=
null
;
s=Single.getInstance();
s.print();
}
}