求:java实例源代码答:import java.awt.*; import java.awt.event.*; import java.lang.*; import javax.swing.*; public class Counter extends Frame { //声明三个面板的布局 GridLayout gl1,gl2,gl3; Panel p0,p1,p2,p3; JTextField tf1; TextField tf2; Button b0,b1,b2,b3,b4,b5,b6,b7,b8,b9,b10,b11,b12,b13,...