http://www.geeksforgeeks.org/move-zeroes-end-array/

MoveZerosToEnd.java

public class MoveZerosToEnd {
	public static int[] move(int[] arr){
		int current=0;
		for(int i=0;i<arr.length;i++){
			if(arr[i]!=0)
				arr[current++]=arr[i];
		}
		while(current<arr.length)
			arr[current++]=0;
		return arr;
	}
}

MoveZerosToEndTest.java

public class MoveZerosToEndTest {
	@Test
	public void testMove() {
		assertArrayEquals(new int[]{}, MoveZerosToEnd.move(new int[]{}));
		assertArrayEquals(new int[]{0}, MoveZerosToEnd.move(new int[]{0}));
		assertArrayEquals(new int[]{1}, MoveZerosToEnd.move(new int[]{1}));
		assertArrayEquals(new int[]{1,2,3,4}, MoveZerosToEnd.move(new int[]{1,2,3,4}));
		assertArrayEquals(new int[]{1,2,3,0}, MoveZerosToEnd.move(new int[]{1,2,3,0}));
		assertArrayEquals(new int[]{1,3,2,0}, MoveZerosToEnd.move(new int[]{1,0,3,2}));
		assertArrayEquals(new int[]{1,2,0,0}, MoveZerosToEnd.move(new int[]{1,0,0,2}));
		assertArrayEquals(new int[]{1,0,0,0}, MoveZerosToEnd.move(new int[]{0,0,0,1}));
	}
}