老师应该是说int类型成员变量的初始值为0；其他八种成员变量的默认初始值是

For type byte, the default value is zero, that is, the value of (byte)0. 
For type short, the default value is zero, that is, the value of (short)0. 
For type int, the default value is zero, that is, 0. 
For type long, the default value is zero, that is, 0L. 
For type float, the default value is positive zero, that is, 0.0f. 
For type double, the default value is positive zero, that is, 0.0d. 
For type char, the default value is the null character, that is, '\u0000'. 
For type boolean, the default value is false.