方法重载

public class TestCode {
   
    public void myMethod(String s) {
        System.out.println("My String");
    }
    
    public void myMethod(Object o) {
        System.out.println("My Object");
    }
    
    public void myMethod(char o) {
        System.out.println("My char");
    }
    
    public static void main(String args[]){
        TestCode t = new TestCode();
        t.myMethod(null);
    }
}