I have a char and I need a String. How do I convert from one to the other?
12 Answers
You can use Character.toString(char). Note that this method simply returns a call to String.valueOf(char), which also works.
As others have noted, string concatenation works as a shortcut as well:
String s = "" + 's';But this compiles down to:
String s = new StringBuilder().append("").append('s').toString();which is less efficient because the StringBuilder is backed by a char[] (over-allocated by StringBuilder() to 16), only for that array to be defensively copied by the resulting String.
String.valueOf(char) "gets in the back door" by wrapping the char in a single-element array and passing it to the package private constructor String(char[], boolean), which avoids the array copy.
I've got of the following five six methods to do it.
// Method #1
String stringValueOf = String.valueOf('c'); // most efficient
// Method #2
String stringValueOfCharArray = String.valueOf(new char[]{x});
// Method #3
String characterToString = Character.toString('c');
// Method #4
String characterObjectToString = new Character('c').toString();
// Method #5
// Although this approach seems very simple,
// this is less efficient because the concatenation
// expands to a StringBuilder.
String concatBlankString = 'c' + "";
// Method #6
String fromCharArray = new String(new char[]{x});Note: Character.toString(char) returns String.valueOf(char). So effectively both are same.
String.valueOf(char[] value) invokes new String(char[] value), which in turn sets the value char array.
public String(char value[]) { this.value = Arrays.copyOf(value, value.length);
}On the other hand String.valueOf(char value) invokes the following package private constructor.
String(char[] value, boolean share) { // assert share : "unshared not supported"; this.value = value;
}Source code from String.java in Java 8 source code
Hence
String.valueOf(char)seems to be most efficient method, in terms of both memory and speed, for convertingchartoString.
Sources:
0Below are various ways to convert to char c to String s (in decreasing order of speed and efficiency)
char c = 'a';
String s = String.valueOf(c); // fastest + memory efficient
String s = Character.toString(c);
String s = new String(new char[]{c});
String s = String.valueOf(new char[]{c});
String s = new Character(c).toString();
String s = "" + c; // slowest + memory inefficientUse the Character.toString() method like so:
char mChar = 'l';
String s = Character.toString(mChar);Use any of the following:
String str = String.valueOf('c');
String str = Character.toString('c');
String str = 'c' + "";As @WarFox stated - there are 6 methods to convert char to string. However, the fastest one would be via concatenation, despite answers above stating that it is String.valueOf. Here is benchmark that proves that:
@BenchmarkMode(Mode.Throughput)
@Fork(1)
@State(Scope.Thread)
@Warmup(iterations = 10, time = 1, batchSize = 1000, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 10, time = 1, batchSize = 1000, timeUnit = TimeUnit.SECONDS)
public class CharToStringConversion { private char c = 'c'; @Benchmark public String stringValueOf() { return String.valueOf(c); } @Benchmark public String stringValueOfCharArray() { return String.valueOf(new char[]{c}); } @Benchmark public String characterToString() { return Character.toString(c); } @Benchmark public String characterObjectToString() { return new Character(c).toString(); } @Benchmark public String concatBlankStringPre() { return c + ""; } @Benchmark public String concatBlankStringPost() { return "" + c; } @Benchmark public String fromCharArray() { return new String(new char[]{c}); }
}And result:
Benchmark Mode Cnt Score Error Units
CharToStringConversion.characterObjectToString thrpt 10 82132.021 ± 6841.497 ops/s
CharToStringConversion.characterToString thrpt 10 118232.069 ± 8242.847 ops/s
CharToStringConversion.concatBlankStringPost thrpt 10 136960.733 ± 9779.938 ops/s
CharToStringConversion.concatBlankStringPre thrpt 10 137244.446 ± 9113.373 ops/s
CharToStringConversion.fromCharArray thrpt 10 85464.842 ± 3127.211 ops/s
CharToStringConversion.stringValueOf thrpt 10 119281.976 ± 7053.832 ops/s
CharToStringConversion.stringValueOfCharArray thrpt 10 86563.837 ± 6436.527 ops/sAs you can see, the fastest one would be c + "" or "" + c;
VM version: JDK 1.8.0_131, VM 25.131-b11This performance difference is due to -XX:+OptimizeStringConcat optimization. You can read about it here.
Try this: Character.toString(aChar) or just this: aChar + ""
We have various ways to convert a char to String. One way is to make use of static method toString() in Character class:
char ch = 'I';
String str1 = Character.toString(ch);Actually this toString method internally makes use of valueOf method from String class which makes use of char array:
public static String toString(char c) { return String.valueOf(c);
}So second way is to use this directly:
String str2 = String.valueOf(ch);This valueOf method in String class makes use of char array:
public static String valueOf(char c) { char data[] = {c}; return new String(data, true);
}So the third way is to make use of an anonymous array to wrap a single character and then passing it to String constructor:
String str4 = new String(new char[]{ch});The fourth way is to make use of concatenation:
String str3 = "" + ch;This will actually make use of append method from StringBuilder class which is actually preferred when we are doing concatenation in a loop.
Here are a few methods, in no particular order:
char c = 'c';
String s = Character.toString(c); // Most efficient way
s = new Character(c).toString(); // Same as above except new Character objects needs to be garbage-collected
s = c + ""; // Least efficient and most memory-inefficient, but common amongst beginners because of its simplicity
s = String.valueOf(c); // Also quite common
s = String.format("%c", c); // Not common
Formatter formatter = new Formatter();
s = formatter.format("%c", c).toString(); // Same as above
formatter.close();I am converting Char Array to String
Char[] CharArray={ 'A', 'B', 'C'};
String text = String.copyValueOf(CharArray); char vIn = 'A'; String vOut = Character.toString(vIn);For these types of conversion, I have site bookmarked called It helps me quickly get the conversion code for most of the languages I use.
I've tried the suggestions but ended up implementing it as follows
editView.setFilters(new InputFilter[]{new InputFilter() { @Override public CharSequence filter(CharSequence source, int start, int end, Spanned dest, int dstart, int dend) { String prefix = "http://"; //make sure our prefix is visible String destination = dest.toString(); //Check If we already have our prefix - make sure it doesn't //get deleted if (destination.startsWith(prefix) && (dstart <= prefix.length() - 1)) { //Yep - our prefix gets modified - try preventing it. int newEnd = (dend >= prefix.length()) ? dend : prefix.length(); SpannableStringBuilder builder = new SpannableStringBuilder( destination.substring(dstart, newEnd)); builder.append(source); if (source instanceof Spanned) { TextUtils.copySpansFrom( (Spanned) source, 0, source.length(), null, builder, newEnd); } return builder; } else { //Accept original replacement (by returning null) return null; } } }});
