1.public class 和class定義類的區別?
public class:文件名稱和類名稱不一致,一個*.java文件之中只能存在一個public class 定義。
class:文件名稱和類名稱不一致,一個*.java文件之中可以同時存在多個class定義,並且編譯之後會形成不同的*.class文件。
2.classpath和path的區別?
classpath:是JVM進行類加載時候所需要使用類的加載途徑;
path:exe的路徑
3.Java中的數據類型劃分及默認值:
基本數據類型:
數值型:
整型:byte short int long; 0
浮點型:float、double;0.0
字符型:char;
布爾型:boolean;false
引用數據類型:數組、類、接口 NULL
今天的一個練習題:
class Person{
private int num;
private String name;
private String job;
private double sal;
private double comm;
public Person() {}
public Person(int n,String nam,String j,double s,double c){
num = n;
name = nam;
job =j;
sal=s;
comm=c;
}
public void setNum(int n){
num=n;
}
public void setName(String nam){
name=nam;
}
public void setJob(String j){
job=j;
}
public void setSal(double s){
sal=s;
}
public void setComm(double c){
comm=c;
}
public int getNum(){
return num;
}
public String getName(){
return name;
}
public String getJob(){
return job;
}
public double getSal(){
return sal;
}
public double getComm(){
return comm;
}
public double salary(){
return sal+comm ;
}
public double income(){
return this.salary() * 12;
}
public String getInfo(){
return "Information:" + "\n" +
"\t|-Number:"+this.getNum()+"\n"+
"\t|-Name:"+this.getName()+"\n"+
"\t|-JOB:"+this.getJob()+"\n"+
"\t|-Wages:"+this.getSal()+"\n"+
"\t|-Commission:"+this.getComm()+"\n"+
"\t|-Monthly pay:"+this.salary()+"\n"+
"\t|-Yearly salary:"+this.income()+"\n";
}
}
public class Day
{
public static void main(String args[]){
Person pp=new Person(6666,"hy","BOSS",9000.2,1000.3);
System.out.println(pp.getInfo());
}
}
編譯通過: