Array Binary search
In this chapter you will learn:
Binary search an Array
The following methods binary search array elements.
static int binarySearch(byte[] a, byte key)static int binarySearch(byte[] a, int fromIndex, int toIndex, byte key)static int binarySearch(char[] a, char key)static int binarySearch(char[] a, int fromIndex, int toIndex, char key)static int binarySearch(double[] a, double key)static int binarySearch(double[] a, int fromIndex, int toIndex, double key)static int binarySearch(float[] a, float key)static int binarySearch(float[] a, int fromIndex, int toIndex, float key)static int binarySearch(int[] a, int key)static int binarySearch(int[] a, int fromIndex, int toIndex, int key)static int binarySearch(long[] a, int fromIndex, int toIndex, long key)static int binarySearch(long[] a, long key)static int binarySearch(Object[] a, int fromIndex, int toIndex, Object key)static int binarySearch(Object[] a, Object key)static int binarySearch(short[] a, int fromIndex, int toIndex, short key)static int binarySearch(short[] a, short key)static<T> int binarySearch(T[] a, int fromIndex, int toIndex, T key, Comparator<? super T> c)static<T> int binarySearch(T[] a, T key, Comparator<? super T> c)
import java.util.Arrays;
//from ja v a 2 s .c o m
public class Main{
public static void main(String args[]) {
int array[] = new int[10];
for (int i = 0; i < 10; i++){
array[i] = -3 * i;
}
System.out.print("Original contents: ");
System.out.println(Arrays.toString(array));
Arrays.sort(array);
System.out.print("Sorted: ");
System.out.println(Arrays.toString(array));
System.out.print("The value -9 is at location ");
int index = Arrays.binarySearch(array, -9);
System.out.println(index);
}
}
The output:
Binary Search on byte Array
Performing Binary Search on byte Array
import java.util.Arrays;
/* j av a 2s. c o m*/
public class Main {
public static void main(String[] args) {
byte bArray[] = {1, 2, 3, 4, 5};
Arrays.sort(bArray);
byte searchValue = 2;
int intResult = Arrays.binarySearch(bArray, searchValue);
System.out.println("Result of binary search of 2 is : " + intResult);
searchValue = 3;
intResult = Arrays.binarySearch(bArray, searchValue);
System.out.println("Result of binary search of 3 is : " + intResult);
}
}
The output:
Insert an Element into a Sorted Array
import java.util.Arrays;
/*j a v a 2 s . c om*/
public class Main {
public static void main(String[] argv) {
String[] oldArray = new String[] { "a", "b", "c", "d" };
int index = Arrays.binarySearch(oldArray, "e");
if (index < 0) {
int insertIndex = -index - 1;
String[] newArray = new String[oldArray.length + 1];
System.arraycopy(oldArray, 0, newArray, 0, insertIndex);
System.arraycopy(oldArray, insertIndex, newArray, insertIndex + 1,
oldArray.length - insertIndex);
newArray[insertIndex] = "e";
oldArray = newArray;
}
System.out.println(Arrays.toString(oldArray));
}
}
The code above generates the following result.
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What you will learn in the next chapter:
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