ONP

public class Onp1 {

	public static void main(String[] args) {
		String[] onp = new String[args.length];
		int j = 0;
		String[] stack = new String[10];
		int stackPosition = -1;
		for(String str: args)
		{
			onp[j] = "";
			if(str.endsWith("=")){
				for(int i=0; i< str.length(); i++)
					if(str.charAt(i) >= '0' && str.charAt(i) <= '9' || str.charAt(i) == '.'){
						onp[j] += str.charAt(i);
						if(!(str.charAt(i+1) >= '0' && str.charAt(i+1) <= '9' && str.charAt(i+1) == '.'))
							onp[j] += " ";
					}
					else{
						switch(str.charAt(i)){
						case '-':
						case '+':{
							while(stackPosition >= 0 && !stack[stackPosition].equals("( ")){
								onp[j] += stack[stackPosition] + " ";
								--stackPosition;
							}
							stack[++stackPosition] = str.charAt(i) + " ";
							break;
						}
						case '*':
						case '/':{
							while(stackPosition >= 0 && !stack[stackPosition].equals("( ") && !stack[stackPosition].equals("- ") && !stack[stackPosition].equals("+ ")){
								onp[j] += stack[stackPosition] + " ";
								--stackPosition;
							}
							stack[++stackPosition] = str.charAt(i) + " ";
							break;
						}
						case '^':
							while(stackPosition >= 0 && !stack[stackPosition].equals("( ") && !stack[stackPosition].equals("- ") && !stack[stackPosition].equals("+ ") && !stack[stackPosition].equals("* ") && !stack[stackPosition].equals("/ ")){
								onp[j] += stack[stackPosition] + " ";
								--stackPosition;
							}
							stack[++stackPosition] = str.charAt(i) + " ";
							break;
						case '(':
							stack[++stackPosition] = str.charAt(i) + " ";
							break;
						case ')':
							while(stackPosition >= 0 && !stack[stackPosition].equals("( ")){
								onp[j] += stack[stackPosition] + " ";
								--stackPosition;
							}
							--stackPosition;
							break;
						case '=':
							while(stackPosition >= 0 && !stack[stackPosition].equals("( ")){
								onp[j] += stack[stackPosition] + " ";
								--stackPosition;
							}
							onp[j] += str.charAt(i) + " ";
							break;
						default:
							break;
					}
					}
			}
			else
				System.out.println(str + ": Bledne rownanie");
			System.out.println(args[j]);
			System.out.println(onp[j]);
			j++;
		}

	}

}