Important things in Java

int [] A = new int [n];

for (int x : A) System.out.println (x);

int[] array = new int[4];
Arrays.fill(array, 0);

System.out.println(Arrays.deepToString(array));

Math.max (a, b)

Math.abs (a)

StringBuilder:

StringBuilder res = new StringBuilder ();

res.append (char ('A'));

res.append (String);

String ans = res.toString();

int[] array = new int[4];
Arrays.fill(array, 0);

Arrays.Sort (object[], startIndex, endIndex);

Set st = new HashSet  ();
st.add (5);
st.size();

List  list = new ArrayList  ();
Concerting Set to List type
List  list = new ArrayList  (st);
Collection.sort (list);

String s = new String();
s.toCharArray();

Input Output Code in Java (Code is taken from Egor's library).



	class InputReader {
	private InputStream stream;
	private byte[] buf = new byte[1024];
	private int curChar;
	private int numChars;
	private SpaceCharFilter filter;
	public InputReader(InputStream stream) {
	this.stream = stream;
	}
	public int read() {
	if (numChars == -1)
	throw new InputMismatchException();
	if (curChar >= numChars) {
	curChar = 0;
	try {
	numChars = stream.read(buf);
	} catch (IOException e) {
	throw new InputMismatchException();
	}
	if (numChars <= 0)
	return -1;
	}
	return buf[curChar++];
	}
	public int readInt() {
	int c = read();
	while (isSpaceChar(c))
	c = read();
	int sgn = 1;
	if (c == '-') {
	sgn = -1;
	c = read();
	}
	int res = 0;
	do {
	if (c < '0' || c > '9')
	throw new InputMismatchException();
	res *= 10;
	res += c - '0';
	c = read();
	} while (!isSpaceChar(c));
	return res * sgn;
	}
	public long readLong() {
	int c = read();
	while (isSpaceChar(c))
	c = read();
	int sgn = 1;
	if (c == '-') {
	sgn = -1;
	c = read();
	}
	long res = 0;
	do {
	if (c < '0' || c > '9')
	throw new InputMismatchException();
	res *= 10;
	res += c - '0';
	c = read();
	} while (!isSpaceChar(c));
	return res * sgn;
	}
	public String readString() {
	int c = read();
	while (isSpaceChar(c))
	c = read();
	StringBuilder res = new StringBuilder();
	do {
	res.appendCodePoint(c);
	c = read();
	} while (!isSpaceChar(c));
	return res.toString();
	}
	public boolean isSpaceChar(int c) {
	if (filter != null)
	return filter.isSpaceChar(c);
	return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}
	public String next() {
	return readString();
	}
	public interface SpaceCharFilter {
	public boolean isSpaceChar(int ch);
	}
	}
	class OutputWriter {
	private final PrintWriter writer;
	public OutputWriter(OutputStream outputStream) {
	writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
	}
	public OutputWriter(Writer writer) {
	this.writer = new PrintWriter(writer);
	}
	public void print(Object...objects) {
	for (int i = 0; i < objects.length; i++) {
	if (i != 0)
	writer.print(' ');
	writer.print(objects[i]);
	}
	}
	public void printLine(Object...objects) {
	print(objects);
	writer.println();
	}
	public void close() {
	writer.close();
	}
	}

view raw InputOutputClass.java hosted with ❤ by GitHub

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If you want to use something other, this is Parser class for input (Written by Rudradevbasak's team proof). For output, you can use PrintWriter class which is fast enough.

	private static class Parser
	{
	final private int BUFFER_SIZE = 1 << 16;
	private DataInputStream din;
	private byte[] buffer;
	private int bufferPointer, bytesRead;
	public Parser(InputStream in)
	{
	din = new DataInputStream(in);
	buffer = new byte[BUFFER_SIZE];
	bufferPointer = bytesRead = 0;
	}
	public int ni() throws Exception
	{
	int ret = 0;
	byte c = read();
	while (c <= ' ') c = read();
	boolean neg = c == '-';
	if (neg) c = read();
	do
	{
	ret = ret * 10 + c - '0';
	c = read();
	} while (c > ' ');
	if (neg) return -ret;
	return ret;
	}
	public long nl() throws Exception
	{
	long ret = 0;
	byte c = read();
	while (c <= ' ') c = read();
	boolean neg = c == '-';
	if (neg) c = read();
	do
	{
	ret = ret * 10 + c - '0';
	c = read();
	} while (c > ' ');
	if (neg) return -ret;
	return ret;
	}
	public String ns() throws Exception
	{
	StringBuffer ret=new StringBuffer();
	byte c = read();
	while (c <= ' ') c = read();
	do
	{
	ret = ret.append((char)c);
	c = read();
	} while (c > ' ');
	return ret.toString();
	}
	private void fillBuffer() throws Exception
	{
	bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
	if (bytesRead == -1) buffer[0] = -1;
	}
	private byte read() throws Exception
	{
	if (bufferPointer == bytesRead) fillBuffer();
	return buffer[bufferPointer++];
	}
	}

view raw Parser.java hosted with ❤ by GitHub