ByteCodeIterator.java

package week05.jvm.loader;

import java.util.Arrays;

import week05.jvm.util.Util;

public class ByteCodeIterator {
	byte[] codes;
	int pos = 0;

	public ByteCodeIterator(byte[] codes) {
		this.codes = codes;
	}

	public int nextU1ToInt() {
		return Util.byteToInt(new byte[]{codes[pos++]});
	}
	
	public int nextU2ToInt() {
		return Util.byteToInt(new byte[]{codes[pos++],codes[pos++]});
	}
	
	public String nextU4ToHexString() {
		return Util.byteToHexString(new byte[]{codes[pos++],codes[pos++],codes[pos++],codes[pos++]});
	}

	public byte[] getBytes(int len) {
		if(pos + len >= codes.length){
			throw new ArrayIndexOutOfBoundsException();
		}
		
		byte[] data = Arrays.copyOfRange(codes, pos, pos + len);
		pos += len;
		return data;
	}

}