Java-Code-Snippet.md

Java-Code-Snippet

Row Sum (2d array)

for (int row = 0; row < matrix.length; ++row) {
    int rowSum = 0;
    for (int col = 0; col < matrix[row].length; ++col) {
        rowSum += matrix[row][col];
    }
    System.out.println("row sum: " + rowSum);
}   

Column Sum (2d array)

// when length of each row is same
for (int col = 0; col < matrix[0].length; ++col) {
    int colSum = 0;
    for (int row = 0; row < matrix.length; ++row) {
        colSum += matrix[row][col];
    }
    System.out.println("col sum: " + colSum);
}

Copy Array

// Any changes made to copied object will not be reflected in original object or vice-versa.
String[] temp = Arrays.copyOf(inputArray, inputArray.length);

List to Array

String

List<String> res = new ArrayList<String>();
res.toArray(new String[0]);

int

List<Integer> res = new ArrayList<Integer>();
res.stream().mapToInt(i->i).toArray();

String to charecter frequency array

int [] s1Freq = new int [26];
for(int i = 0; i < s1.length(); ++i){
    s1Freq[s1.charAt(i) - 'a']++; 
}

Digit Sum

String number = "2345";
for (int x = 0; x < number.length(); x++)
   sum += Integer.parseInt(number.charAt(x)+"");

Converting minutes to 24 hour format

int hours = minutes / 60;
int minutes = minutes % 60;