[java] what is Ljava.lang.String;@

I have a string array selectCancel with setter and getter methods, which is a checkbox in my form. I am trying to get the checked values and I am getting the above result when I print.

I tried the Arrays.toString() method but it still prints the same.

I then did the following:

String checked = Arrays.toString(Employee.getSelectCancel());

I also tried with the Arrays.asList() and Arrays.copyOf()

So, how do I read this string?

This question is related to java arrays string

The answer is


Ljava.lang.String;@ is returned where you used string arrays as strings. Employee.getSelectCancel() does not seem to return a String[]


[ stands for single dimension array
Ljava.lang.String stands for the string class (L followed by class/interface name)

Few Examples:

  1. Class.forName("[D") -> Array of primitive double
  2. Class.forName("[[Ljava.lang.String") -> Two dimensional array of strings.

List of notations:
Element Type : Notation
boolean : Z
byte : B
char : C
class or interface : Lclassname
double : D
float : F
int : I
long : J
short : S


According to the Java Virtual Machine Specification (Java SE 8), JVM ยง4.3.2. Field Descriptors:

FieldType term | Type      | Interpretation
-------------- | --------- | --------------
L ClassName ;  | reference | an instance of class ClassName
[              | reference | one array dimension
...            | ...       | ...

the expression [Ljava.lang.String;@45a877 means this is an array ( [ ) of class java.lang.String ( Ljava.lang.String; ). And @45a877 is the address where the String object is stored in memory.


I also met this problem when I've made ListView for android app:

Map<String, Object> m;

for(int i=0; i < dates.length; i++){
    m = new HashMap<String, Object>();
    m.put(ATTR_DATES, dates[i]);
    m.put(ATTR_SQUATS, squats[i]);
    m.put(ATTR_BP, benchpress[i]);
    m.put(ATTR_ROW, row[i]);
    data.add(m);
}

The problem was that I've forgotten to use the [i] index inside the loop


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