Java Object toString()用法及代码示例

Java中的每个类都是直接或间接成为Object类的子级。对象类包含toString()方法。我们可以使用toString()方法来获取对象的字符串表示形式。每当我们尝试打印对象引用时，就会在内部调用toString()方法。如果我们没有在您的类中定义toString()方法，则将调用对象类toString()方法，否则将调用我们的已实现/重写的toString()方法。

对象类toString()方法的语法：

public String toString()
{
      return getClass().getName()+"@"+Integer.toHexString(hashCode());
}

// Java program to illustrate 
// working of toString() method 
class Best_Friend { 
    String name; 
    int age; 
    String college; 
    String course; 
    String address; 
    Best_Friend 
    (String name, int age, String college, String course, String address) 
    { 
        this.name = name; 
        this.age = age; 
        this.college = college; 
        this.course = course; 
        this.address = address; 
    } 
public static void main(String[] args) 
    { 
        Best_Friend b =  
        new Best_Friend("Gulpreet Kaur", 21, "BIT MESRA", "M.TECH", "Kiriburu"); 
        System.out.println(b); 
        System.out.println(b.toString()); 
    } 
}

输出：

Best_Friend@232204a1
Best_Friend@232204a1

说明：在上面的程序中，我们创建一个Best_Friend类的对象，并提供朋友的所有信息。但是，当我们尝试打印对象时，我们会得到一些输出，输出形式为classname @ HashCode_in_Hexadeciaml_form。如果我们想要有关Best_friend对象的正确信息，则必须在Best_Friend类中重写Object类的toString()方法。

// Java program to illustrate 
// working of toString() method 
class Best_Friend { 
    String name; 
    int age; 
    String college; 
    String course; 
    String address; 
    Best_Friend 
    (String name, int age, String college, String course, String address) 
    { 
        this.name = name; 
        this.age = age; 
        this.college = college; 
        this.course = course; 
        this.address = address; 
    } 
public String toString() 
    { 
        return name + " " + age + " " + college + " " + course + " " + address; 
    } 
public static void main(String[] args) 
    { 
        Best_Friend b =  
        new Best_Friend("Gulpreet Kaur", 21, "BIT MESRA", "M.TECH", "Kiriburu"); 
        System.out.println(b); 
        System.out.println(b.toString()); 
    } 
}

输出：

Gulpreet Kaur 21 BIT MESRA M.TECH Kiriburu
Gulpreet Kaur 21 BIT MESRA M.TECH Kiriburu

注意：在所有包装器类中，所有集合类，String类，StringBuffer，StringBuilder类toString()方法均被覆盖以表示有意义的String表示形式。因此，强烈建议在我们的类中也重写toString()方法。

// Java program to illustrate 
// working of toString() method 
import java.util.*; 
class Best_Friend { 
    String name; 
    int age; 
    String college; 
    String course; 
    String address; 
    Best_Friend 
    (String name, int age, String college, String course, String address) 
    { 
        this.name = name; 
        this.age = age; 
        this.college = college; 
        this.course = course; 
        this.address = address; 
    } 
public static void main(String[] args) 
    { 
        Best_Friend b =  
        new Best_Friend("Gulpreet Kaur", 21, "BIT MESRA", "M.TECH", "Kiriburu"); 
        System.out.println(b); 
        String s = new String("Gulpreet Kaur"); 
        System.out.println(s); 
        Integer i = new Integer(21); 
        System.out.println(i); 
        ArrayList l = new ArrayList(); 
        l.add("BIT"); 
        l.add("M.TECH"); 
        System.out.println(l); 
    } 
}

输出：

Best_Friend@232204a1
Gulpreet Kaur
21
[BIT, M.TECH]

相关用法

注：本文由纯净天空筛选整理自 Object toString() Method in Java。非经特殊声明，原始代码版权归原作者所有，本译文未经允许或授权，请勿转载或复制。