java Things that are searched many times [java beginner]

Will be added at any time.

1, how to take length

int array

int [] intArray = {1,2,3,4,5};
System.out.println(intArray.length);

Output: 5

String string

String text = "text";
System.out.println(text.length());

Output: 4

StringBuilder type string

StringBuilder sb = new StringBuilder();
sb.append("text");
System.out.println(sb.length());

Output: 4

2, type conversion

String >> int conversion

String StringA = "0";
int intA = Integer.parseInt(StringA);

int >> String conversion

int intB = 0;
String stringB = String.valueOf(intB);

int >> Integer conversion

int intC = 0;
Integer integerC = intC;        

Integer >> int conversion

Integer integerD = 0;
int intD = integerD.intValue();

char >> String conversion

String strText = String.valueOf('a');

3, Array sort (when each element is Integer)

Array sort (ascending order)

Arrays.sort(array);

Array sort (descending order)

Arrays.sort(array, Collections.reverseOrder());

Or

Arrays.sort(array, Collections.reverseOrder());

String sort

String strtext = "cbda";
System.out.println(strtext);
char[] charText = strtext.toCharArray();
Arrays.sort(charText);
String sortedText = new String(charText);
System.out.println(sortedText);

output

cbda
abcd

Initialization

List initialization

List<Integer> list1 = Arrays.asList(1,2);