package
    class
        method (function)
            statements
                expression

------------

package mypkg;

class C
{
    void f() {
        int i = 1 + 2 * 3;

        Object o = inputNumber();
        if (isNumber(o)) {
            int i2 = convertToNumber(o);
            doSg2();
            doSg3();
            doSg4();
        } else {
            System.out.println("not a number");
        }

        try {
            int i2 = convertToNumber(o);
            doSg2();
            doSg3();
            doSg4();
        } catch (NotANumberException e) {
            System.out.println("not a number");
        }

        Stack s;
        try {
            s.push(1);
            System.out.println("OK");
        } catch (StackIsFullException e) {
            System.out.println("can't push " + e.notFitInx);
        }
    }
}



// JDK   JRE


literal
    1
    1.1
    "fhdask"
    'a'
    true

non-structured program constructions
    try
    method call
    communication
    break
    continue
    return
    goto


1 | 2       000000000000000001
            000000000000000010
1 || 2

1 + "2"
"1" + "2"