用java实现一个简单的计算器。答:System.exit(0);} } int i;// Strings for Digit & Operator buttons.private final String[] str = { "7", "8", "9", "/", "4", "5", "6", "*","1","2", "3", "-", ".", "0", "=", "+" };// Build buttons.JButton[] buttons = new JButton[str.length...