blocks|key|563488|text|toString应该返回一个String。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|563489|public+String+toString()+{+
++++return+"Name:+'"+%2B+this.name+%2B+"',+Height:+'"+%2B+this.height+%2B+"',+Birthday:+'"+%2B+this.bDay+%2B+"'";
}+|code-block|syntax|javascript|563490|我建议您利用您的集成开发环境的特性来生成toString方法。不要手工编写代码。|563491|例如，只要右键单击源代码并选择Source+>+Generate+toString，Eclipse就可以做到这一点|563492|entityMap^0|0|8|E|6|0|0|K|8|0|F|Q|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|Z|8|@$9|10|A|11|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|12|8|@]|D|@]|E|$]]]|P|$]]

The <code>toString</code> is supposed to return a <code>String</code>.

<pre><code>public String toString() { 
 return "Name: '" + this.name + "', Height: '" + this.height + "', Birthday: '" + this.bDay + "'";
} 
</code></pre>

I suggest you make use of your IDE's features to generate the <code>toString</code> method. Don't hand-code it.

For instance, Eclipse can do so if you simply right-click on the source code and select <code>Source &gt; Generate toString</code>

blocks|key|347366|text|您可以在toString()中创建新对象。使用|type|unstyled|depth|inlineStyleRanges|entityRanges|data|347367|return+"Name+=+"+%2B+this.name+%2B"+height=+"+%2B+this.height;|code-block|syntax|javascript|347368|而不是|347369|return+Kid(this.name,+this.height,+this.bDay);|347370|您可以根据需要更改返回字符串。除了日历，还有其他存储日期的方法。|347371|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

You can creating new object in the toString().
use

<pre><code>return "Name = " + this.name +" height= " + this.height;
</code></pre>

instead of 

<pre><code>return Kid(this.name, this.height, this.bDay);
</code></pre>

You may change the return string as required. There are other ways to store date instead calander.

blocks|key|563606|text|您不能像调用普通方法一样调用构造函数，只能使用new调用它来创建一个新对象：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|563607|Kid+newKid+=+new+Kid(this.name,+this.height,+this.bDay);|code-block|syntax|javascript|563608|但是从toString()方法构造一个新对象并不是您想要做的事情。|563609|entityMap^0|N|3|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

You can't call a constructor as if it was a normal method, you can only call it with <code>new</code> to create a new object:

<pre><code>Kid newKid = new Kid(this.name, this.height, this.bDay);
</code></pre>

But constructing a new object from your toString() method is not what you want to be doing.

blocks|key|347463|text|下面的代码是一个示例。基于同样的问题，代替使用基于IDE的转换，有没有一种更快的方法来实现，以便在将来发生更改时，我们不需要一次又一次地修改值？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|347464|@Override
++++public+String+toString()+{
++++++++return+"ContractDTO{"+%2B
++++++++++++++++"contractId='"+%2B+contractId+%2B+'\''+%2B
++++++++++++++++",+contractTemplateId='"+%2B+contractTemplateId+%2B+'\''+%2B
++++++++++++++++'}';
++++}|code-block|syntax|javascript|347465|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Following code is a sample. Question based on the same, instead of using IDE based conversion, is there a faster way to implement so that in future the changes occur, we do not need to modify the values over and over again?

<pre><code>@Override
 public String toString() {
 return "ContractDTO{" +
 "contractId='" + contractId + '\'' +
 ", contractTemplateId='" + contractTemplateId + '\'' +
 '}';
 }
</code></pre>

blocks|key|563778|text|Java+toString()方法|type|unstyled|depth|inlineStyleRanges|entityRanges|data|563779|如果您想将任何对象表示为字符串，toString()方法就应运而生了。|563780|toString()方法返回对象的字符串表示形式。|563781|如果打印任何对象，java编译器将在内部调用该对象的toString()方法。因此，重写toString()方法，返回所需的输出，它可以是对象的状态等，这取决于您的实现。|563782|Java+toString()方法的优点|563783|通过覆盖object类的toString()方法，我们可以返回对象的值，因此我们不需要编写太多代码。|563784|不使用toString()方法的输出|563785|class+Student{++
+int+id;++
+String+name;++
+String+address;++

+Student(int+id,+String+name,+String+address){++
+this.id=id;++
+this.name=name;++
+this.address=address;++
+}++

+public+static+void+main(String+args[]){++
+++Student+s1=new+Student(100,”Joe”,”success”);++
+++Student+s2=new+Student(50,”Jeff”,”fail”);++

+++System.out.println(s1);//compiler+writes+here+s1.toString()++
+++System.out.println(s2);//compiler+writes+here+s2.toString()++
+}++
}++

Output:Student@2kaa9dc
+++++++Student@4bbc148|code-block|syntax|javascript|563786|你可以在上面的例子中看到#1.打印s1和s2会打印对象的Hashcode值，但我想打印这些对象的值。由于java编译器在内部调用toString()方法，因此覆盖此方法将返回指定的值。让我们通过下面的例子来理解它：|563787|Example#2

Output+with+overriding+toString()+method

class+Student{++
+int+id;++
+String+name;++
+String+address;++

+Student(int+id,+String+name,+String+address){++
+this.id=id;++
+this.name=name;++
+this.address=address;++
+}++

//overriding+the+toString()+method++
public+String+toString(){+
++return+id%2B"+"%2Bname%2B"+"%2Baddress;++
+}++
+public+static+void+main(String+args[]){++
+++Student+s1=new+Student(100,”Joe”,”success”);++
+++Student+s2=new+Student(50,”Jeff”,”fail”);++

+++System.out.println(s1);//compiler+writes+here+s1.toString()++
+++System.out.println(s2);//compiler+writes+here+s2.toString()++
+}++
}+

Output:100+Joe+success
+++++++50+Jeff+fail|563788|请注意，toString()主要与Java语言中的多态性概念有关。在Eclipse中，尝试单击toString()并右键单击it.Then，单击Open声明并查看超类toString()的来源。|563789|entityMap^0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|12|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|13|8|@]|9|@]|A|$]]|$1|H|3|I|5|6|7|14|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|15|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|16|8|@]|9|@]|A|$]]|$1|N|3|O|5|P|7|17|8|@]|9|@]|A|$Q|R]]|$1|S|3|T|5|6|7|18|8|@]|9|@]|A|$]]|$1|U|3|V|5|P|7|19|8|@]|9|@]|A|$Q|R]]|$1|W|3|X|5|6|7|1A|8|@]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|Z|$]]

Java toString() method

If you want to represent any object as a string, toString() method comes into existence.

The toString() method returns the string representation of the object.

If you print any object, java compiler internally invokes the toString() method on the object. So overriding the toString() method, returns the desired output, it can be the state of an object etc. depends on your implementation.

Advantage of Java toString() method

By overriding the toString() method of the Object class, we can return values of the object, so we don't need to write much code.

Output without toString() method

<pre><code>class Student{ 
 int id; 
 String name; 
 String address; 

 Student(int id, String name, String address){ 
 this.id=id; 
 this.name=name; 
 this.address=address; 
 } 

 public static void main(String args[]){ 
 Student s1=new Student(100,”Joe”,”success”); 
 Student s2=new Student(50,”Jeff”,”fail”); 

 System.out.println(s1);//compiler writes here s1.toString() 
 System.out.println(s2);//compiler writes here s2.toString() 
 } 
} 

Output:Student@2kaa9dc
 Student@4bbc148
</code></pre>

You can see in the above example #1. printing s1 and s2 prints the Hashcode values of the objects but I want to print the values of these objects. Since java compiler internally calls toString() method, overriding this method will return the specified values. Let's understand it with the example given below:

<pre><code>Example#2

Output with overriding toString() method

class Student{ 
 int id; 
 String name; 
 String address; 

 Student(int id, String name, String address){ 
 this.id=id; 
 this.name=name; 
 this.address=address; 
 } 

//overriding the toString() method 
public String toString(){ 
 return id+" "+name+" "+address; 
 } 
 public static void main(String args[]){ 
 Student s1=new Student(100,”Joe”,”success”); 
 Student s2=new Student(50,”Jeff”,”fail”); 

 System.out.println(s1);//compiler writes here s1.toString() 
 System.out.println(s2);//compiler writes here s2.toString() 
 } 
} 

Output:100 Joe success
 50 Jeff fail
</code></pre>

Note that toString() mostly is related to the concept of polymorphism in Java.
In, Eclipse, try to click on toString() and right click on it.Then, click on Open Declaration and see where the Superclass toString() comes from.

blocks|key|563855|text|实际上，您需要返回如下内容，因为toString必须返回一个字符串|type|unstyled|depth|inlineStyleRanges|entityRanges|data|563856|public+String+toString()+{
+return+"Name+:"+%2B+this.name+%2B+"whatever+:"+%2B+this.whatever+%2B+"";
}|code-block|syntax|javascript|563857|你实际上在构造器中做了一些错误的事情，你将用户设置的变量设置为name，而你需要做相反的事情。你不应该做的事情|563858|n+=+this.name|563859|你应该做什么|563860|this.name+=+n|563861|希望这能有所帮助，谢谢|563862|entityMap^0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|W|8|@]|9|@]|A|$]]|$1|M|3|N|5|D|7|X|8|@]|9|@]|A|$E|F]]|$1|O|3|P|5|6|7|Y|8|@]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

Well actually you will need to return something like this because toString has to return a string

<pre><code>public String toString() {
 return "Name :" + this.name + "whatever :" + this.whatever + "";
}
</code></pre>

and you actually do something wrong in the constructer you set the variable the user set to the name while you need to do the opposite.
What you shouldn't do

<pre><code>n = this.name
</code></pre>

What you should do

<pre><code>this.name = n
</code></pre>

Hopes this helps thanks

blocks|key|563916|text|我们甚至可以这样编写:在类中创建一个新的String对象，在构造函数中为其赋值，并在被覆盖的toString方法中返回该对象|type|unstyled|depth|inlineStyleRanges|entityRanges|data|563917|public+class+Student{++
+int+id;++
+String+name;++
+String+address;++
+String+details;
+Student(int+id,+String+name,+String+address){++
+this.id=id;++
+this.name=name;++
+this.address=address;++
+this.details=id%2B"++"%2Bname%2B"++"%2Baddress;++
+}++

//overriding+the+toString()+method++
public+String+toString(){+
++return+details;++
+}++
+public+static+void+main(String+args[]){++
+++Student+s1=new+Student(100,"Joe","success");++
+++Student+s2=new+Student(50,"Jeff","fail");++

+++System.out.println(s1);//compiler+writes+here+s1.toString()++
+++System.out.println(s2);//compiler+writes+here+s2.toString()++
+}++
}|code-block|syntax|javascript|563918|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

we can even write like this by creating a new String object in the class and assigning it what ever we want in constructor and return that in toString method which is overridden

<pre><code>public class Student{ 
 int id; 
 String name; 
 String address; 
 String details;
 Student(int id, String name, String address){ 
 this.id=id; 
 this.name=name; 
 this.address=address; 
 this.details=id+" "+name+" "+address; 
 } 

//overriding the toString() method 
public String toString(){ 
 return details; 
 } 
 public static void main(String args[]){ 
 Student s1=new Student(100,"Joe","success"); 
 Student s2=new Student(50,"Jeff","fail"); 

 System.out.println(s1);//compiler writes here s1.toString() 
 System.out.println(s2);//compiler writes here s2.toString() 
 } 
}
</code></pre>

blocks|key|347969|text|如果你对单元测试感兴趣，你可以声明一个公共的"ToStringTemplate"，然后你就可以对你的toString进行单元测试了。即使你不对它进行单元测试，我也认为它“更干净”，并使用了String.format。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|347970|public+class+Kid+{

++++public+static+final+String+ToStringTemplate+=+"KidName='%251s',+Height='%252s',+GregCalendar='%253s'";

++++private+String+kidName;
++++private+double+height;
++++private+GregorianCalendar+gregCalendar;

++++public+String+getKidName()+{
++++++++return+kidName;
++++}

++++public+void+setKidName(String+kidName)+{
++++++++this.kidName+=+kidName;
++++}

++++public+double+getHeight()+{
++++++++return+height;
++++}

++++public+void+setHeight(double+height)+{
++++++++this.height+=+height;
++++}

++++public+GregorianCalendar+getGregCalendar()+{
++++++++return+gregCalendar;
++++}

++++public+void+setGregCalendar(GregorianCalendar+gregCalendar)+{
++++++++this.gregCalendar+=+gregCalendar;
++++}

++++public+String+toString()+{+
++++++++return+String.format(ToStringTemplate,+this.getKidName(),+this.getHeight(),+this.getGregCalendar());
++++}+
}|code-block|syntax|javascript|347971|现在，您可以通过创建Kid、设置属性、在ToStringTemplate上执行自己的string.format并进行比较来进行单元测试。|347972|将ToStringTemplate设为静态最终意味着事实的“一个版本”，而不是在单元测试中拥有模板的“副本”。|347973|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

If you're interested in Unit-Tests, then you can declare a public "ToStringTemplate", and then you can unit test your toString. Even if you don't unit-test it, I think its "cleaner" and uses String.format.

<pre><code>public class Kid {

 public static final String ToStringTemplate = "KidName='%1s', Height='%2s', GregCalendar='%3s'";

 private String kidName;
 private double height;
 private GregorianCalendar gregCalendar;

 public String getKidName() {
 return kidName;
 }

 public void setKidName(String kidName) {
 this.kidName = kidName;
 }

 public double getHeight() {
 return height;
 }

 public void setHeight(double height) {
 this.height = height;
 }

 public GregorianCalendar getGregCalendar() {
 return gregCalendar;
 }

 public void setGregCalendar(GregorianCalendar gregCalendar) {
 this.gregCalendar = gregCalendar;
 }

 public String toString() { 
 return String.format(ToStringTemplate, this.getKidName(), this.getHeight(), this.getGregCalendar());
 } 
}
</code></pre>

Now you can unit test by create the Kid, setting the properties, and doing your own string.format on the ToStringTemplate and comparing.

making ToStringTemplate static-final means "ONE VERSION" of the truth, rather than having a "copy" of the template in the unit-test.

blocks|key|563993|text|在我看来，最好的方法是使用google+gson库：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|563994|++++++++@Override
public+String+toString()+{
++++return+new+GsonBuilder().setPrettyPrinting().create().toJson(this);
}|code-block|syntax|javascript|563995|或者apache+commons+lang反射方式|563996|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

The best way in my opinion is using google gson library:

<pre><code> @Override
public String toString() {
 return new GsonBuilder().setPrettyPrinting().create().toJson(this);
}
</code></pre>

or apache commons lang reflection way

blocks|key|348093|text|简洁的方式就是使用Lombok注解。它具有@ToString注释，该注释将生成toString()方法的实现。默认情况下，它将按顺序打印您的类名以及每个字段，以逗号分隔。通过将参数传递给注释，您可以轻松地自定义输出，例如：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|348094|@ToString(of+=+{"name",+"lastName"})|code-block|syntax|javascript|348095|它等同于纯Java：|348096|public+String+toString()+{
++++++++return+"Person(name="+%2B+this.name+%2B+",+lastName="+%2B+this.experienceInYears+%2B+")";
++++}|348097|entityMap^0|L|9|13|A|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|V|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|W|8|@]|D|@]|E|$]]|$1|M|3|N|5|H|7|X|8|@]|D|@]|E|$I|J]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

Nice and concise way is to use Lombok annotations. It has <code>@ToString</code> annotation, which will generate an implementation of the <code>toString()</code> method. By default, it will print your class name, along with each field, in order, separated by commas.
You can easily customize your output by passing parameters to annotation, e.g.:

<pre><code>@ToString(of = {"name", "lastName"})
</code></pre>

Which is equivalent of pure Java:

<pre><code>public String toString() {
 return "Person(name=" + this.name + ", lastName=" + this.experienceInYears + ")";
 }
</code></pre>

Sounds a little stupid, but I need help on my <code>toString()</code> method and it is very irking. 
I tried looking up online because the <code>toString</code> is the one where it is screwing up and "not finding Kid constructor #2" even though it is there and I would even do something else and it doesn't work.
Ok that was a lot so here is my code: 

<pre><code>import java.util.*; 
 class Kid { 
 String name; 
 double height; 
 GregorianCalendar bDay; 

 public Kid () { 
 this.name = "HEAD";
 this.height = 1; 
 this.bDay = new GregorianCalendar(1111,1,1); 
 } 

 public Kid (String n, double h, String date) {
 // method that toString() can't find somehow
 StringTokenizer st = new StringTokenizer(date, "/", true);
 n = this.name;
 h = this.height;
 } 

 public String toString() { 
 return Kid(this.name, this.height, this.bDay);
 } 
 } //end class 
</code></pre>

Ok So my toString above (I know, my third parameter is off, should be a String) is off. If I hardcode a value in for the third thing it goes haywire and says it can't find this (up above). So how can I get the date and break it up?

Class calling this is below

<pre><code>class Driver { 
 public static void main (String[] args) { 
 Kid kid1 = new Kid("Lexie", 2.6, "11/5/2009"); 
 System.out.println(kid1.toString());
 } //end main method 
} //end class 
</code></pre>

I tried researching multiple constructors and it really didn't help.
I tried researching <code>toString()</code> methods, and tried using previous <code>toString()</code> methods logic that I created previous but this is brand new so it never worked.

Help?

How to override toString() properly in Java?

集成开发环境

单元测试

编译器

Eclipse

Java

听起来有点愚蠢，但是我的toString()方法需要帮助，而且它非常烦人。我尝试在网上查找，因为是toString搞砸了，“找不到Kid构造函数#2”，即使它在那里，我甚至会做一些其他的事情，但它不起作用。好吧，这是很多，所以这是我的代码：import java.util.*;    class Kid {      ...

问如何在Java中正确覆盖toString()？
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