Frequently used Java code blocks for Interview or code test

Get a string from standard input

InputStreamReader isr = new InputStreamReader(System.in);
BufferedReader buffer = new BufferedReader(isr);
String s = buffer.readLine();

Type cast a String to int

String str = "123";
Integer.parseInt(str);

Type cast a String to double

String str = "123.45";
Double D = Double.valueOf(str);
double d = D.doubleValue();

Bubble Sort

public void bubbleSort(int[] arr) {
    boolean swapped = true;
    for (int j = 1; swapped; j++){
        swapped = false;
        for (int i = 0; i < arr.length - j; i++) {
            if (arr[i] > arr[i + 1]) {                          
                int tmp = arr[i];
                arr[i] = arr[i + 1];
                arr[i + 1] = tmp;
                swapped = true;
            }
        }                
    }
}

Selection Sort

public void selectionSort(int[] arr){
    for(int j=0; j<arr.length-1; j++){
        int min = j;
        for(i=j+1; i<arr.length; i++)
            if(arr[i] < arr[min])
                min = in;
        swap(arr[j],arr[min]);
    }
}