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Java - uppercase all ArrayList elements
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In this article, we would like to show you how to uppercase all ArrayList elements in Java.
In this example, we use for loop to transform all the elements from letters ArrayList to uppercase.
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import java.util.*;2
3
public class Example {4
5
public static void main(String[] args) {6
List<String> letters = new ArrayList<>();7
letters.add("a");8
letters.add("b");9
letters.add("c");10
11
for (int i = 0; i < letters.size(); i++) {12
String newValue = letters.get(i).toUpperCase(Locale.ROOT);13
letters.set(i, newValue);14
}15
16
System.out.println(letters);17
}18
}Output:
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[A, B, C]In this example, we use for-each loop to transform all the elements from letters ArrayList to uppercase.
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import java.util.*;2
3
public class Example {4
5
public static void main(String[] args) {6
List<String> letters = new ArrayList<>();7
letters.add("a");8
letters.add("b");9
letters.add("c");10
11
for (String letter : letters) {12
String newValue = letter.toUpperCase(Locale.ROOT);13
letters.set(letters.indexOf(letter), newValue);14
}15
16
System.out.println(letters);17
}18
}Output:
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[A, B, C]In this example, we use a stream with map() function to transform all the elements from letters ArrayList to uppercase and collect them in the new ArrayList - lettersToUpper.
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import java.util.*;2
import java.util.stream.Collectors;3
4
public class Example {5
6
public static void main(String[] args) {7
List<String> letters = new ArrayList<>();8
letters.add("a");9
letters.add("b");10
letters.add("c");11
12
System.out.println("Before: " + letters);13
14
List<String> lettersToUpper = letters.stream()15
.map(String::toUpperCase)16
.collect(Collectors.toList());17
18
System.out.println("After: " + lettersToUpper);19
}20
}Output:
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Before: [a, b, c]2
After: [A, B, C]