Java 8+
Use String.join():
String str = String.join(",", arr);
Note that arr can also be any Iterable (such as a list), not just an array.
If you have a Stream, you can use the joining collector:
Stream.of("a", "b", "c")
.collect(Collectors.joining(","))
Legacy (Java 7 and earlier)
StringBuilder builder = new StringBuilder();
for(String s : arr) {
builder.append(s);
}
String str = builder.toString();
Alternatively, if you just want a "debug-style" dump of an array:
String str = Arrays.toString(arr);
Note that if you're really legacy (Java 1.4 and earlier) you'll need to replace StringBuilder there with StringBuffer.
Android
Use TextUtils.join():
String str = TextUtils.join(",", arr);
General notes
You can modify all the above examples depending on what characters, if any, you want in between strings.
DON'T use a string and just append to it with += in a loop like some of the answers show here. This sends the GC through the roof because you're creating and throwing away as many string objects as you have items in your array. For small arrays you might not really notice the difference, but for large ones it can be orders of magnitude slower.
Answer from Michael Berry on Stack OverflowHow to convert an int array to String with toString method in Java - Stack Overflow
string to string array conversion in java - Stack Overflow
[University Programming (java)] Converting an array to string?
using the toString method...how would I pass an array through?
Java 8+
Use String.join():
String str = String.join(",", arr);
Note that arr can also be any Iterable (such as a list), not just an array.
If you have a Stream, you can use the joining collector:
Stream.of("a", "b", "c")
.collect(Collectors.joining(","))
Legacy (Java 7 and earlier)
StringBuilder builder = new StringBuilder();
for(String s : arr) {
builder.append(s);
}
String str = builder.toString();
Alternatively, if you just want a "debug-style" dump of an array:
String str = Arrays.toString(arr);
Note that if you're really legacy (Java 1.4 and earlier) you'll need to replace StringBuilder there with StringBuffer.
Android
Use TextUtils.join():
String str = TextUtils.join(",", arr);
General notes
You can modify all the above examples depending on what characters, if any, you want in between strings.
DON'T use a string and just append to it with += in a loop like some of the answers show here. This sends the GC through the roof because you're creating and throwing away as many string objects as you have items in your array. For small arrays you might not really notice the difference, but for large ones it can be orders of magnitude slower.
Use Apache commons StringUtils.join(). It takes an array, as a parameter (and also has overloads for Iterable and Iterator parameters) and calls toString() on each element (if it is not null) to get each elements string representation. Each elements string representation is then joined into one string with a separator in between if one is specified:
String joinedString = StringUtils.join(new Object[]{"a", "b", 1}, "-");
System.out.println(joinedString);
Produces:
a-b-1
What you want is the Arrays.toString(int[]) method:
import java.util.Arrays;
int[] array = new int[lnr.getLineNumber() + 1];
int i = 0;
..
System.out.println(Arrays.toString(array));
There is a static Arrays.toString helper method for every different primitive java type; the one for int[] says this:
public static String toString(int[] a)Returns a string representation of the contents of the specified array. The string representation consists of a list of the array's elements, enclosed in square brackets (
"[]"). Adjacent elements are separated by the characters", "(a comma followed by a space). Elements are converted to strings as byString.valueOf(int). Returns"null"ifais null.
Very much agreed with @Patrik M, but the thing with Arrays.toString is that it includes "[" and "]" and "," in the output. So I'll simply use a regex to remove them from outout like this
String strOfInts = Arrays.toString(intArray).replaceAll("\\[|\\]|,|\\s", "");
and now you have a String which can be parsed back to java.lang.Number, for example,
long veryLongNumber = Long.parseLong(intStr);
Or you can use the java 8 streams, if you hate regex,
String strOfInts = Arrays
.stream(intArray)
.mapToObj(String::valueOf)
.reduce((a, b) -> a.concat(",").concat(b))
.get();
To start you off on your assignment, String.split splits strings on a regular expression and this expression may be an empty string:
String[] ary = "abc".split("");
Yields the array:
(java.lang.String[]) [, a, b, c]
Getting rid of the empty 1st entry is left as an exercise for the reader :-)
Note: In Java 8, the empty first element is no longer included.
String strName = "name";
String[] strArray = new String[] {strName};
System.out.println(strArray[0]); //prints "name"
The second line allocates a String array with the length of 1. Note that you don't need to specify a length yourself, such as:
String[] strArray = new String[1];
instead, the length is determined by the number of elements in the initalizer. Using
String[] strArray = new String[] {strName, "name1", "name2"};
creates an array with a length of 3.
This is driving me nuts:
Array is as follows:
String[] myarray = new String[5];
myarray[0] = {"foo"}
myarray[1] = {"."}
myarray[2] = {"this"}
myarray[3] = {"."}
myarray[4] = {"bar"}Im trying to convert it to a string using Arrays.toString but its not working:
String mystring = new String(Arrays.toString(myarray)); System.out.println(mystring);
this prints out: [foo, ., this, ., bar]
why?
i just want: foo.this.bar
I also don't understand the methods on stackexchange
Every tutorial I see on YouTube shows how to pass 1,2, or 3 individual variables through methods using toString.
How do I do it if I want to pass an array...like a simple array of 10 numbers.
I want one method to set the array with the 10 numbers (which I know how to do with a for loop) but rather than print it in a separate for loop in the same method...I want to use toString and thus produce those 10 numbers in that separate method.
How do I go about doing that?