++i和i++对比

单独执行VS赋值

class Add{
       public static void main(String[] args){
          int a = 1;
          int b = 1;
      int c = 1;
      int d = 1;

      a++;
          ++b;
      int  m = c++;
      int  n = ++d;
      System.out.println("a="+a);
      System.out.println("b="+b);
      System.out.println("m="+m);
      System.out.println("n="+n);
}
}

a=2
b=2
m=1
n=2

++i 先增加，后引用

number = ++i;
System.out.println(number);
//等价于
i = i + 1;
number = i;
System.out.println(number);

i++ 先引用，后增加

//先引用，后增加
number = i++;
System.out.println(number);
//等价于
tmp = i;
number = tmp;
i = i + 1;
System.out.println(number);

print打印不换行

class Test1{
          public static void main (String[] args){
                   System.out.print("Hello!");
                   System.out.print("Hello!");
                   System.out.print("Hello!");
                   }
}

Hello!Hello!Hello!

println打印完，光标自动定位到下一行

class Test1{
          public static void main (String[] args){
                   System.out.println("Hello!");
                   System.out.println("Hello!");
                   System.out.println("Hello!"); 
                   }
}

Hello!
Hello!
Hello!