final修饰符

public class FinalVar {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println(Price.INSTANCE.currentPrice);
        Price price=new Price(2.8);
        System.out.println(price.currentPrice);
    }
}
class Price{
    static Price INSTANCE=new Price(2.8);
    static double initPrice=20;
    /*
     * 若调整 上面两句话的顺序
     * 则结果改为  17.2    17.2
     */
    
    double currentPrice;
    public Price(double discount) {
        // TODO Auto-generated constructor stub
        currentPrice=initPrice-discount;
    }
     
}

-2.8
17.2

public class FinalVar {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        System.out.println(Price.INSTANCE.currentPrice);
        Price price=new Price(2.8);
        System.out.println(price.currentPrice);
    }
}
class Price{
    final static Price INSTANCE=new Price(2.8);
    final static double initPrice=20;
    double currentPrice;
    public Price(double discount) {
        // TODO Auto-generated constructor stub
        currentPrice=initPrice-discount;
    }
     
}

17.2
17.2

public class FinalDefine {
    String s00="java";
    String s01="1";
    
    String s0=s00+s01;
    String s1="java1";
    String s2="java"+String.valueOf(1);
    String s3="java"+1;
    
    
    final String sf00="java";
    final String sf01="1";
    String sf0=sf00+sf01;
    final String sf1="java1";
    final String sf2="java"+String.valueOf(1);
    final String sf3="java"+1;
    
    
    final String str1;
    final String str2;
    final String str3="java";
    {
        str1="java";
    }
    public FinalDefine(){
        str2="java";
    }
    
    
    final static String str11;
    final static String str12="java";
    
    static {
        str11="java";
    }
    
    void charge(){
        
        System.out.println(s0==s1);
        System.out.println(s1==s2);
        System.out.println(s1==s3);
        System.out.println(str1+str1=="javajava");
        System.out.println(str2+str2=="javajava");
        System.out.println(str3+str3=="javajava");
        
        System.out.println();
        
       
        System.out.println(sf0==sf1);
        System.out.println(sf1==sf2);
        System.out.println(sf1==sf3);
         System.out.println(str11+str11=="javajava");
        System.out.println(str12+str12=="javajava");
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        FinalDefine fDefine=new FinalDefine();
        fDefine.charge();
    }
    
}

false
false
true
false
false
true

true
false
true
false
true