Simple Example
public static void main(String argv[]) {
Method void main(java.lang.String[])
0 iconst_1 //push const 1 to the stack
1 istore_1 //stack top to the lv[1]
2 iconst_2 //push const 2 to the stack
3 istore_2 //stack top to the lv[2]
4 iload_1 //push lv[1] to the stack
5 iload_2 //push lv[2] to the stack
6 iadd //add 2 top stack positions.
7 istore_3 //stack top to the lv[1]