java--object类

java.lang.Object类。


当打印引用时，实际 上会打印引用所指对象的toString()方法的返回值，因为每个类都直接或间接地继承自Object,而Object类中包含了toString()，因此每个类都 有toString()这个方法
public class ObjectTest {
public static void main(String[] args) {
Object object = new Object();
System.out.println(object);
System.out.println(object.toString());


String str = "aaa";
System.out.println(str);
System.out.println(str.toString);

Student student = new Student();
System.out.println(student);
System.out.println(student.toString());
}
}


class Student {
public String toString() {
return "hello world";
}
}




··············
public calss StringTest {
public static void main(String[] args) {
String str = new String("aa");
String str2= new String("aa");
System.out.println(str.equals(str2));


String str3 = "aa";
String str4 = "aa";
System.out.println(str3.equals(str4));




Object object = new Object();
Object object2 = new Object();
System.out.println(object.equals(object2));


}
}








API(Application Prongramming Interface)应用编程接口。