java学习part22包装类

119-面向对象(高级)-包装类的理解_基本数据类型与包装类间的转换_哔哩哔哩_bilibili

1.包装类

 

2.基本转包装方式

2.1new方式

 

源码

2.2valueof（）

3.包装转基本

 4.基本类型和包装类型的默认值不一样

比如boolean默认false

Boolean默认null（对象）

通过初始值的不一样，可以分辨某些对象是否初始化过还是归零了

5.自动装箱拆箱

 6.String和其他类型转换

import java.util.Scanner;
import java.util.Vector;public class Main {//求最大public static void main(String[] args) {Main m = new Main();System.out.println(  m.maxScoreFunc() );}int maxScoreFunc2(){Vector v = new Vector();Scanner scan = new Scanner(System.in);int maxScore = 0;while(true){System.out.println("print in");int intScore = scan.nextInt();if(intScore < 0){break;}//  Integer score = Integer.valueOf(intScore);//自动装箱成对象放入向量v.addElement(intScore);maxScore = intScore > maxScore? intScore:maxScore;}for(int i=0;i < v.size();i++){//取对象拆箱Object objScore = v.elementAt(i);int intScore = (Integer) objScore;if(maxScore - 10 > intScore){System.out.println("B等级");}}return maxScore;}int maxScoreFunc(){Scanner scan = new Scanner(System.in);int maxScore = 0;while(true){System.out.println("print in");int intScore = scan.nextInt();if(intScore < 0){break;}maxScore = intScore > maxScore? intScore:maxScore;}//System.out.println(maxScore);return maxScore;}}