blocks|key|5191747|text|main是一个静态方法，您可以从它调用静态方法，也可以创建类的实例并调用它的实例方法。同样，在本例中，list是一个实例变量，因此不能从静态方法访问它。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|5191748|我相信对你来说最好的选择是这样做：|5191749|public+static+void+main(String[]+args)+{
++++study+s+=+new+study();
++++s.printSymbol();
}|code-block|syntax|javascript|5191750|另外，请在类中使用大写名称。|5191751|entityMap^0|0|4|1F|4|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]|$9|T|A|U|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|V|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|X|8|@]|D|@]|E|$]]|$1|O|3|-4|5|6|7|Y|8|@]|D|@]|E|$]]]|P|$]]

<code>main</code> is a static method and from it you may either call static methods, or you have to create an instance of the class and call instance methods of it. Also in your case <code>list</code> is an instance variable and thus it can not be accessed from static methods.

I believe the best option for you is to do something like:

<pre><code>public static void main(String[] args) {
 study s = new study();
 s.printSymbol();
}
</code></pre>

Also please use capital names for classes.

blocks|key|2154475|text|您的main方法是静态的，这意味着无需创建对象就可以调用它。Main方法必须始终是静态的，因为在程序启动时，您还没有对象。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2154476|关于静态方法的事情是，你只能从它访问其他静态成员，除非你创建一个你使用的对象。|2154477|您有两种可能的解决方案：|2154478|将其他成员设置为静态的，我不推荐这样做，因为您已经在使用一个字段，或者使用一个对象：|2154479|public+static+void+main(String[]+args)+{
++++study+myObject+=+new+study();
++++study.printSymbol();
}|code-block|syntax|javascript|2154480|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|Q|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|R|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|S|8|@]|9|@]|A|$K|L]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Your main method is static, which means it can be called without creating an object. Main methods always have to be static, because on startup of the program you don't have an object yet.

The thing about static methods is, you can only access other static members from it unless you create an object you work with.

You have two possible solutions:

Make the other members static, which I wouldn't recommend as you are already using a field, or use an object:

<pre><code>public static void main(String[] args) {
 study myObject = new study();
 study.printSymbol();
}
</code></pre>

blocks|key|5191825|text|+public+`static`+String+printSymbol(){

+public+`static`+void+addSymbols(){|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|5191826|main方法处于静态上下文中，因此它调用的所有其他方法也需要处于静态上下文中。|unstyled|offset|length|style|CODE|5191827|entityMap^0|0|0|4|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@$G|O|H|P|I|J]]|9|@]|A|$]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code> public `static` String printSymbol(){

 public `static` void addSymbols(){
</code></pre>

The <code>main</code> method is in static context, so all other method its calling needs to be as well.

blocks|key|2160423|text|将静态和非静态上下文混合在一起会造成混乱。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2160424|printSymbol()方法是类study的一部分。(请改用Study，这是正确的约定。有关这些约定的更多信息，请查看here)。|offset|length|style|CODE|2160425|main方法位于静态上下文中。这意味着您需要创建一个Study类的对象，然后对该对象调用printSymbol方法。|2160426|public+static+void+main(String[]+args)
{
++++Study+study+=+new+Study();+//+create+a+new+object+of+the+class+Study
++++study.printSymbol();+++++++//+call+the+printSymbol+method+on+this+object
}|code-block|syntax|javascript|2160427|您也可以将printSymbol()方法和ArrayList设置为静态的，但这在面向对象语言Java中不是好做法。|2160428|entityMap|0|LINK|mutability|MUTABLE|url|http://www.oracle.com/technetwork/java/javase/documentation/codeconvtoc-136057.html^0|0|0|D|H|5|V|5|1O|4|0|0|Q|5|0|0|5|D|L|9|0^^$0|@$1|2|3|4|5|6|7|Y|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Z|8|@$D|10|E|11|F|G]|$D|12|E|13|F|G]|$D|14|E|15|F|G]]|9|@$D|16|E|17|1|18]]|A|$]]|$1|H|3|I|5|6|7|19|8|@$D|1A|E|1B|F|G]]|9|@]|A|$]]|$1|J|3|K|5|L|7|1C|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|6|7|1D|8|@$D|1E|E|1F|F|G]|$D|1G|E|1H|F|G]]|9|@]|A|$]]|$1|Q|3|-4|5|6|7|1I|8|@]|9|@]|A|$]]]|R|$S|$5|T|U|V|A|$W|X]]]]

You're messing up by mixing static and non-static contexts.

The <code>printSymbol()</code> method is part of the class <code>study</code>. (Use <code>Study</code> instead, that's the proper convention. For more information on these conventions, look <a href="http://www.oracle.com/technetwork/java/javase/documentation/codeconvtoc-136057.html" rel="nofollow" title="Java Code Conventions">here</a>).

The main method is in a static context. This means that you need to make an object of the class <code>Study</code> and then call the printSymbol method on that object.

<pre><code>public static void main(String[] args)
{
 Study study = new Study(); // create a new object of the class Study
 study.printSymbol(); // call the printSymbol method on this object
}
</code></pre>

You could also make the <code>printSymbol()</code> method and the <code>ArrayList</code> static, but that is bad practice in Java, which is an object oriented language.

blocks|key|247613|text|import+java.util.*;
import+java.lang.Math;
public+class+study+{
public+static+void+main(String[]+args)+{
+++study+newStudy+=+new+study();
+++newStudy.addSymbols();
+++newStudy.printSymbol();
}
ArrayList<String>+list+=+new+ArrayList<String>();
public+void+addSymbols(){
+++list.add("a");
+++list.add("b");
+++list.add("c");
+++list.add("d");
+++list.add("e");
}

public+String+printSymbol(){
++++int+x=(int)+Math.floor(Math.random()*4)%2B1;
++++String+y+=+list.get(x);
++++return+y;
}
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|247614|你的随机数也是错的，它需要是Math.random()*4。我刚刚用ASCII码替换了你的符号，以便我的机器能理解。|unstyled|247615|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>import java.util.*;
import java.lang.Math;
public class study {
public static void main(String[] args) {
 study newStudy = new study();
 newStudy.addSymbols();
 newStudy.printSymbol();
}
ArrayList&lt;String&gt; list = new ArrayList&lt;String&gt;();
public void addSymbols(){
 list.add("a");
 list.add("b");
 list.add("c");
 list.add("d");
 list.add("e");
}

public String printSymbol(){
 int x=(int) Math.floor(Math.random()*4)+1;
 String y = list.get(x);
 return y;
}
}
</code></pre>

Your random was also wrong, its needs to be Math.random()*4.
I just replaced your symbols with ASCII for my machine to understand.

blocks|key|3077127|text|就像每个人建议的那样，避免使用静态方法，创建一个对象，然后调用你的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3077128|不要忘记将符号添加到数组列表中，您可以在创建对象之后、调用printSymbol()之前在构造函数或main方法中添加符号|offset|length|style|CODE|3077129|public+static+void+main(String[]+args)+{
++++new+study().printSymbol();
}
public+study()+{
++++//+add+symbols+to+the+array+list
++++addSymbols();
}|code-block|syntax|javascript|3077130|或|3077131|public+static+void+main(String[]+args)+{
++++study+s+=+new+study();
++++//+add+symbols+to+the+array+list
++++s.addSymbols();
++++s.printSymbol();
}|3077132|同样在convention中，类名应该以大写字母开头。|3077133|entityMap|0|LINK|mutability|MUTABLE|url|http://www.oracle.com/technetwork/java/javase/documentation/codeconvtoc-136057.html^0|0|T|D|0|0|0|0|3|A|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@$D|12|E|13|F|G]]|9|@]|A|$]]|$1|H|3|I|5|J|7|14|8|@]|9|@]|A|$K|L]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|A|$]]|$1|O|3|P|5|J|7|16|8|@]|9|@]|A|$K|L]]|$1|Q|3|R|5|6|7|17|8|@]|9|@$D|18|E|19|1|1A]]|A|$]]|$1|S|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

Like every one suggested, avoid static method and create an object then call your methods. 

And dont forget to add the symbols to the arraylist, you can do it in the constructor or in the main method after creating the object and before calling <code>printSymbol()</code>

<pre><code>public static void main(String[] args) {
 new study().printSymbol();
}
public study() {
 // add symbols to the array list
 addSymbols();
}
</code></pre>

Or

<pre><code>public static void main(String[] args) {
 study s = new study();
 // add symbols to the array list
 s.addSymbols();
 s.printSymbol();
}
</code></pre>

Also by <a href="http://www.oracle.com/technetwork/java/javase/documentation/codeconvtoc-136057.html" rel="nofollow">convention</a> Classnames should start with an upser case letter.

I want this code to generate a random number between one and five and then, using that number, chose a symbol out of my <code>arraylist</code> and print it. Whenever I try to call the <code>printSymbol()</code> method it tells me to change it and the <code>arraylist</code> to static. When I do it gives me two errors on the method call line in my main method and the line where it says that <code>String y = list.get(x);</code> I want to know how to make it so I can call this method and get it to print String y for me.

<pre><code>import java.util.*;
import java.lang.Math;
public class study {
public static void main(String[] args) {
 printSymbol();
}
ArrayList&lt;String&gt; list = new ArrayList&lt;String&gt;();
public void addSymbols(){
 list.add("あ");
 list.add("い");
 list.add("う");
 list.add("え");
 list.add("お");
}
public String printSymbol(){
 int x=(int) Math.floor(Math.random()*5)+1;
 String y = list.get(x);
 return y;
}

}
</code></pre>

Calling method in main method

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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我希望这段代码生成一个介于1和5之间的随机数，然后使用这个数字，从我的arraylist中选择一个符号并打印出来。每当我尝试调用printSymbol()方法时，它都会告诉我要将其和arraylist更改为static。当我这样做时，它会在我的main方法的方法调用行上给我两个错误，还有一行是String y = li...

问main方法中的调用方法
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