How to convert the Object[] to String[] in Java?

Question

Hi, everyone,

I have a question about Java. I have an Object[] (Java default, not the user-defined) and I want to convert it to a String[]. Can anyone help me? thank you.

Answer 1

this is conversion

for(int i = 0 ; i < objectArr.length ; i ++){  
try{
strArr[i] = objectArr[i].toString();
}catch(NullPointerException ex){
// do some default initilization
}

}  

This is casting

String [] strArr = (String[]) objectArr;  //this will give you class cast exception

Update:

Tweak 1

 String[] stringArray = Arrays.copyOf(objectArray, objectArray.length, String[].class);

Tweak2

 Arrays.asList(Object_Array).toArray(new String[Object_Array.length]);

Note:That only works if the objects are all Strings; his current code works even if they are not

forTweak1 :only on Java 1.6 and above

Answer 2

I think this is the simplest way if all entries in objectArr are String:

for(int i = 0 ; i < objectArr.length ; i ++){
    strArr[i] = (String) objectArr[i];
}

Answer 3

Simply casting like this String[] strings = (String[]) objectArray; probably won't work.

Try something like this:

public static String[] asStrings(Object... objArray) {
    String[] strArray = new String[objArray.length];
    for (int i = 0; i < objArray.length; i++)
        strArray[i] = String.valueOf(objArray[i]);
    return strArray;
}

You could then use the function either like this

Object[] objs = { "hello world", -1.0, 5 };
String[] strings = asStrings(objs);

or like this

String[] strings = asStrings("hello world", -1.0, 5);

Answer 4

I guess you could also use System.arraycopy

System.arraycopy(objarray, 0, strarray, 0, objarray.length);

provided, strarray is of the length objarray.length and objarray contain only strings. Or it would throw ArrayStoreException. See aioobe's comment.