昨晚想到了，发了下没说清楚。今天重新发一下：如下图代码
当有char x时调用的是char x，当没有char x时会调用int x，这涉及到类型提升，请分析下原因。。。。。

兄弟我是啥高手，~我是零基础，刚学也没几天~我进度比较慢~苦熬呢在~

荣凯旋 发表于 2012-1-14 12:54
你的问题我在CSDN上看啦下
当传入常数时，会被当作int处理，例如：

额，终于等到了撒。这个还有窄转换问题。。。。哈哈。。。厉害，高手啊。。。。

你的问题我在CSDN上看啦下
当传入常数时，会被当作int处理，例如：

[java] view plaincopyprint?public class Test {  
  
    void f(char i){System.out.println("arg is char!");};  
    void f(byte i){System.out.println("arg is byte!");};  
    void f(short i){System.out.println("arg is short!");};  
    void f(int i){System.out.println("arg is int!");};  
    void f(long i){System.out.println("arg is long!");};      
    void f(float i){System.out.println("arg is float!");};  
    void f(double i){System.out.println("arg is double!");};  
      
    public static void main(String[] args) {  
        // TODO Auto-generated method stub   
        Test t = new Test();  
        t.f(5);  
    }  
  
}  
public class Test {

        void f(char i){System.out.println("arg is char!");};
        void f(byte i){System.out.println("arg is byte!");};
        void f(short i){System.out.println("arg is short!");};
        void f(int i){System.out.println("arg is int!");};
        void f(long i){System.out.println("arg is long!");};       
        void f(float i){System.out.println("arg is float!");};
        void f(double i){System.out.println("arg is double!");};
       
        public static void main(String[] args) {
                // TODO Auto-generated method stub
        Test t = new Test();
                t.f(5);
        }

}
  

结果会是 arg is int!

那如果没有int形式的参数呢？重载类型会自动提高，例如：

[java] view plaincopyprint?public class Test {  
  
    void f(char i){System.out.println("arg is char!");};  
    void f(byte i){System.out.println("arg is byte!");};  
    void f(short i){System.out.println("arg is short!");};  
    //void f(int i){System.out.println("arg is int!");};   
    void f(long i){System.out.println("arg is long!");};      
    void f(float i){System.out.println("arg is float!");};  
    void f(double i){System.out.println("arg is double!");};  
      
    public static void main(String[] args) {  
        // TODO Auto-generated method stub   
        Test t = new Test();  
        t.f(5);  
    }  
  
}  
public class Test {

        void f(char i){System.out.println("arg is char!");};
        void f(byte i){System.out.println("arg is byte!");};
        void f(short i){System.out.println("arg is short!");};
        //void f(int i){System.out.println("arg is int!");};
        void f(long i){System.out.println("arg is long!");};       
        void f(float i){System.out.println("arg is float!");};
        void f(double i){System.out.println("arg is double!");};
       
        public static void main(String[] args) {
                // TODO Auto-generated method stub
        Test t = new Test();
                t.f(5);
        }

}

结果会是 arg is long!

其他情况类似，会一直提升类型直到能匹配到为止，例如从byte提高到了double：

[c-sharp] view plaincopyprint?public class Test {  
  
    void f(char i){System.out.println("arg is char!");};  
    //void f(byte i){System.out.println("arg is byte!");};   
    //void f(short i){System.out.println("arg is short!");};   
    //void f(int i){System.out.println("arg is int!");};   
    //void f(long i){System.out.println("arg is long!");};     
    //void f(float i){System.out.println("arg is float!");};   
    void f(double i){System.out.println("arg is double!");};  
      
    public static void main(String[] args) {  
        // TODO Auto-generated method stub   
        byte x = 0;  
        Test t = new Test();  
        t.f(x);  
    }  
  
}  
public class Test {

        void f(char i){System.out.println("arg is char!");};
        //void f(byte i){System.out.println("arg is byte!");};
        //void f(short i){System.out.println("arg is short!");};
        //void f(int i){System.out.println("arg is int!");};
        //void f(long i){System.out.println("arg is long!");};       
        //void f(float i){System.out.println("arg is float!");};
        void f(double i){System.out.println("arg is double!");};
       
        public static void main(String[] args) {
                // TODO Auto-generated method stub
        byte x = 0;
                Test t = new Test();
                t.f(x);
        }

}

结果会是 arg is double!

char比较特殊，如果匹配不到会提升至int，如果还匹配不到则继续提升。

那如果传入参数的类型大于形参呢？答案是编译器会告诉你此路不通  
我给你看个自动提升的表，你思考下吧~呵呵，加油兄弟