int one = 10 ;
int two = 20 ;
int three=one+two;//这样子是可以的，但是改成两步：int three=0;three=one+two;就不对了，请各位大佬解答一下，谢谢了。
System.out.println("three = one + two ==> "+three);
three+=one;
System.out.println("three += one ==> "+three);
three*=one;
System.out.println("three *= one ==> "+three);
three/=one；
System.out.println("three /= one ==> "+three);
three%=one;
System.out.println("three %= one ==> "+three);
你的第一种写法int three=one+two,这样写虽然能够实现出来，在慕课网的编辑器中看不出来问题。但在eclipse中会有警告提示。所以这种写法是不对的，这样写的话变量three的值是不被使用的，这样就没有意义了。
我重新按照你的来弄了一遍，得到的输出是这样的
three = one + two ==>30<br/>three += one ==>40<br/>three -= one ==>30<br/>three *= one ==>300<br/>three /= one ==>30<br/>three %= one ==>0<br/>
应该要怎么样才能去掉<br/>呢？
我这样写的，是没问题的。
public class HelloWorld{
public static void main(String[] args) {
int one = 10 ;
int two = 20 ;
int three = 0 ;
three = one + two ;
System.out.println("three = one + two ==>"+three);
three += one ;
System.out.println("three += one ==>"+three);
three -= one ;
System.out.println("three -= one ==>"+three);
three *= one ;
System.out.println("three *= one ==>"+three);
three /= one ;
System.out.println("three /= one ==>"+three);
three %= one ;
System.out.println("three %= one ==>"+three);
貌似同一个类型&&同一个变量，不能被连续分别赋值。
我试过了这么写也没错，不行你就试着不要改动他原来的代码，把three的运算写在println后面的括号里面。