test_java.rar_Java 8

import java.awt.*; import java.awt.event.*; import javax.swing.*; public class Calculator extends JFrame implements ActionListener { /** * */ private static final long serialVersionUID = 1L; private JTextField text; private char op; private float value; private boolean first; public Calculator() { super("计算器"); this.setSize(280,210); this.setLocation(300,240); this.display(); this.setDefaultCloseOperation(EXIT_ON_CLOSE); this.setVisible(true); op='+'; value=0.0f; first=true; } private void display() { text = new JTextField("0.",30); text.setHorizontalAlignment(JTextField.RIGHT); text.setEditable(false); this.getContentPane().add(text,"North"); JPanel panel = new JPanel(new GridLayout(5,4,5,5)); this.getContentPane().add(panel); String str[]={"sqrt","+/-","Backspace","C","7","8","9","/","4","5","6","*","1","2","3","-","0",".","=","+"}; JButton buttons[] = new JButton[str.length]; for (int i=0; i<buttons.length; i++) { buttons[i] = new JButton(str[i]); panel.add(buttons[i]); buttons[i].addActionListener(this); } } public void actionPerformed(ActionEvent e) { String current = e.getActionCommand(); if (current=="C") { text.setText("0."); value = 0.0f; first = true; return; } if (current=="Backspace") { String str=text.getText().substring(0,text.getText().length()-1); text.setText(str); if (str=="") { text.setText("0."); first = true; } return; } if (current.charAt(0)>='0' && current.charAt(0)<='9' || current==".") { if (first) { text.setText(""); first = false; } text.setText(text.getText()+current); } else { System.out.print(""+value+op+text.getText()+"="); switch (op) { case '+': value += Float.parseFloat(text.getText());break; case '-': value -= Float.parseFloat(text.getText());break; case '*': value *= Float.parseFloat(text.getText());break; case '/': value /= Float.parseFloat(text.getText());break; } System.out.println(""+value); text.setText(""+value); op = current.charAt(0); first = true; } } /** * @param args */ public static void main(String[] args) { // TODO Auto-generated method stub new Calculator(); } }