What is the best and effective way to read chars from string in java

Question

I want to know the effective way of reading a string which does not affect memory nor performance of the program.

I have the following implementation:

String x = "<BigBus><color>RED</color><number>123</number>........</BigBus>";
    char[] xh = new char[x.length()];
    for(int i=0;x.length();i+) {
       ch[i]=x.charAt(i);
       System.out.println(ch[i]);
    }

The sample string larger and have multiple lines.

Duplicated http://stackoverflow.com/questions/10006165/converting-string-to-character-array-in-java — cgon, Oct 09 '15 at 07:28

score 2 · Answer 1 · edited Oct 09 '15 at 07:21

2

There is method in string toCharArray()

"aab".toCharArray()

But this method anyway requires additional memory for new char array

edited Oct 09 '15 at 07:21

Mohammad Faisal

5,783
15
70
117

answered Oct 09 '15 at 07:18

Natalia

4,362
24
25

score 1 · Answer 2 · answered Oct 09 '15 at 07:37

Is there a reason why you want to store all the characters of the string in an array? If you just want to print the characters one by one, there's no need to store them in an array.

Your for loop line also contains errors.

String x = "<BigBus><color>RED</color><number>123</number>........</BigBus>";

for(int i=0; i < x.length(); i++) {
    char c = x.charAt(i);
    System.out.println(c);
}

score 1 · Answer 3 · answered Oct 09 '15 at 07:40

1

xh = x.toCharArray();

This'll solve the issue

answered Oct 09 '15 at 07:40

saravanan seenivasan

21
4

catch23 · Accepted Answer · 2015-10-10T07:04:04.627

The best solution will be to use Java 8 features for this.

Method chars() returns chars from given string. But it prints just char number value. For convenience we have to add utility method:

public class IterateString {

    private static void printChar(int aChar) {
        System.out.println((char) (aChar));
    }

    public static void main(String[] args) {
        String str = "<BigBus><color>RED</color><number>123</number>........</BigBus>";

        str.chars()
                .forEach(IterateString::printChar);

        // other options
        System.out.println();
        str.chars()
            .mapToObj(ch -> (char) ch)
            .forEach(System.out::println);

        System.out.println();
        str.chars()
            .filter(Character::isDigit)
            .forEach(IterateString::printChar);
    }
}

With streams you have a lot of benefits as lazy evaluation, lambda syntax, method references... For more info follow java 8 features.

BTW
your code snippet has some mistakes, it should look as follows:

    for (int i = 0; i < str.length(); i++) {
        ch[i] = str.charAt(i);
        System.out.println(ch[i]);
    }

instead of:

char[] xh = new char[x.length()];
for(int i=0; x.length(); i+) {
   ch[i] = x.charAt(i);
   System.out.println(ch[i]);
}

What is the best and effective way to read chars from string in java

4 Answers4