Java Array of Strings in a Class - Curly brace error in Eclipse

Question

I have searched SO for this, and have seen some similar questions, but not this question specifically (that I could find, anyway).

I am receiving a curly-brace / semicolon error on the lines before and after these two statements. They are members of the class (not within a class method). When I remove the array assignment line (second line), the curly-brace / semicolon error goes away. I'm dumbfounded, but know there is a simple answer to this.

public class Test {
    private int var1 = 1;

    // These are the troublesome lines
    public String[] name = new String[10];
    name[0] = "Mary"; // When I remove this line, both the errors go away

    public int var2 = 10;
}

The error(s) in Eclipse (Juno) that I am getting are:

Syntax error on token ";", { expected after this token

...on the error placed on the "var1" line, and:

Syntax error, insert "}" to complete Block

...on the "var2" line.

What am I doing wrong? I have tried different variances, like:

(String) name[0] = "Mary";

...and so on.

Answer 1

The problem is that this statement:

name[0] = "Mary";

isn't in a method, or a constructor, or an instance initializer. Only declarations (and initializers) can be at the top level of a class - not statements.

I suggest you put it in a constructor.

public Test() {
    names[0] = "Mary";
}

Answer 2

public class Test {
    private int var1 = 1;


    // These are the troublesome lines
    public String[] name = new String[10];


    // Use a constructor for initialization or
    // declare the string array as   public String[] name = {"Mary" };
    public Test() {
       name[0] = "Mary"; // When I remove this line, both the errors go away
    }
    public int var2 = 10;
}

In java you have to put statements into methods/blocks.

For example

public class TestB {
    public String[] s = new String[10];


    {
        s[0] = "10";
    }

}

is actually legal (but I wouldn't use it, except maybe for static members)

EDIT: Clarification about static members

Often we have to use pure static objects, in such cases an easy way to provide initialization, is to use an anonymous static block. Something like:

public class TestStatic {
   private String [] someStaticStringArray = new String [10];
   static {
       someStaticStringArray[0] = "foo";
       someStaticStringArray[1] = "bar";
   }
   // Or better with static HashMaps
   private static HashMap<String, String> hm = new HashMap<String, String>();
   static {
     hm.put("key", "val");
     hm.put("key2", "val2");
     hm.put("key3", "val3");
   }
}

For static data members, when I've got no way to provide a factory method or a factory object, I use this way. For non static data members I prefer using constructors, even thou the anonymous block works.

There are many ways to provide initialization in java, I guess personal taste is the main reason for choosing one over another.

For your particular situation I'd go for something like this:

public class TestC {
   // Static data member, constructor does not read data from XML
   private static YourDataObject obj = new YourDataObject();

   public static YourDataObject getInstance(String xmlFile) {
      // Read XML file

      // Actually initialize the instance
      obj.set...(); // 

      // return the instance
      return obj;
   }
}

Answer 3

Try this solution:

public String[] name = new String[10];

//  instance initializer code block comes
{
    name[0] = "Mary";
}

This code block is similar to static initializer blocks ( static { ... } ), but executed at instantiation time, when the variables are initialized.