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Test3.java
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79 lines (66 loc) · 1.94 KB
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package BasicAndDontKnow;
public class Test3 {
/**
* @param args
*/
public static void main(String[] args) {
float float1=0.12f;
System.out.println(float1);
short short1=1;
//short1=short1+1; //将int转换成short类型，错
short1+=1;//隐含强制的类型转换
System.out.println(short1);
//自动装箱与自动拆箱
Integer a=1;//将1自动装箱成Integer类型
Integer b=new Integer(1);
int c=1;
System.out.println(a==b);//两个是引用的是不同的对象
System.out.println(c==a);//自动拆箱后比较
System.out.println(b==c);
Integer aInteger=1,bInteger=1,cInteger=127,dInteger=127;
System.out.printf("a==b:%s\n",aInteger==bInteger);
//根据源码：：当Integer的范围 在-128~127之间时，不会newInteger对象，而是自动引用常量池中的 Integer对象
System.out.printf("c==d:%s\n",cInteger==dInteger);
//& & &&
boolean aboolean=true,bboolean=true;
System.out.println(aboolean&&bboolean);
//Math round:四舍五入，返回最接近的整形
//四舍五入原理：+0.5，然后进行下取整
System.out.println(Math.round(1.5)+ " "+Math.round(-1.5));
//用最有效率的方法计算2*8
System.out.printf("最有效率的方式2*8：2<<3:%s\n",2<<8);
String string[]={"123","234","343"};
int length=string.length;
string[1].length();
Person person=new Person(10, "张三");
grow(person);
System.out.println(person.toString());
}
public static void grow(Person person){
person.setAge(person.getAge()+1);
}
}
class Person{
private int age;
private String name;
public Person(int age,String name){
this.age=age;
this.name=name;
}
public int getAge() {
return age;
}
public String getName() {
return name;
}
public void setAge(int age) {
this.age = age;
}
public void setName(String name) {
this.name = name;
}
@Override
public String toString() {
return "person [age=" + age + ", name=" + name + "]";
}
}