tons.setLayout(newGridLayout(4,5,10,20));for(inti=0;i<20;i++){bg[i]=newJButton(button_name[i]);bg[i].addActionListener(this);//为各个按钮添加事件监听buttons.add(bg[i]);}buttons.setBorder(newLineBorder(display.getBackground(),5));//边框this.setLayout(newBorderLayout());this.add(display_main,BorderLayout.NORTH);this.add(buttons,BorderLayout.SOUTH);setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);//添加关闭窗口事件监听器pack();//自动设置窗体大小setResizable(false);//设置面板大小不可变setVisible(true);Toolkittk=this.getToolkit();Dimensionde=tk.getScreenSize();setBounds((de.width-this.getWidth())/2,(de.height-this.getHeight())/2,this.getWidth(),this.getHeight());//使之居于屏幕正中央}publicvoidactionPerformed(ActionEvente){//事件响应Objectsource=e.getSource();if(operate_flag==true){text.setText("0");operate_flag=false;}if(!("".equals(text.getText()))&;&;text.getText().charAt(0)=='+'){text.setText(text.getText().substring(1,text.getText().length()));}//存在'+',就去掉try{Double.parseDouble(text.getText());}catch(Exceptionee){text.setText("0");}//检测输入数据格式是否合法,不合法就重置为0if(source==c||source==ce){text.setText("0");}elseif(source==backspace){
3
}}}}
}
}}}}
}}}}}
}
if("0".equals(text.getText())||"+".equals(text.getText())||"-".equals(text.getText())){}else{text.setText(text.getText().substring(0,text.getText().length()-1));}elseif(source==bg[0]){setNum