public class UpdateAtIndex {

static class Stack{

private int maxsize;

private int stackArray[];

private int top;

Stack(int size){

maxsize= size;

stackArray= new int[maxsize];

top= -1;

}

public void push(int val){

if(top== maxsize-1){

System.out.println("Stack overflow");

return;

}

stackArray[++top]= val;

System.out.println(val + " pushed into stack");

}

public void updateElement(int index, int val){

if(index<0 || index>top){

System.out.println("Invalid index for element updation");

return;

}

stackArray[index]= val;

System.out.println("Value at index " + index + " replaced by " + val);

}

public void display(){

if(top==-1){

System.out.println("Empty stack");

return;

}

for(int i=0; i<=top; i++){

System.out.print(stackArray[i] + " ");

}

System.out.println();

}

}

public static void main(String[] args) {

Stack st= new Stack(5);

st.push(1);

st.push(2);

st.push(3);

st.push(4);

st.display(); // 1 2 3 4

st.updateElement(2, 94);

st.display(); // 1 2 94 4

}

}