请问怎样知道字符串中包不包含小数点？

Question

String s = "3.1415926";
int i = s.indexOf(".");
if(i<0){
   //有小数点
}

Answer 1

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
public class Calculater_GridLayout extends Applet implements ActionListener 
{
TextField tf=new TextField(12);
Panel p1=new Panel();
Panel p2=new Panel();
Panel p3=new Panel();
Button bt[];
String names[]={"1","2","3","+","4","5","6","-","7","8","9","*","0",".","=","/"};
Button b_c=new Button("          Clear         ");
Button b_e=new Button("  Exit  ");//
Color c=new Color(251,197,103 );
float a,b,result;
int type;
boolean toggle=true;
    public void init()
{
p1.add(tf);
// p2.setLayout(new GridLayout(4,4,5,5));
p2.setLayout(new GridLayout(4,4,5,5));
bt=new Button[names.length];
for(int i=0;i<names.length;i++)
{
bt[i]=new Button(names[i]);
bt[i].addActionListener(this);
p2.add(bt[i]);
}
//setLayout(new GridLayout(3,1,5,5));
p3.add(b_c);
//p3.add(b_e);
add(p1);
add(p2);
add(p3);//
this.setBackground(c);
b_c.addActionListener(this);
b_e.addActionListener(this); }
public void actionPerformed(ActionEvent e)
{
for(int i=0;i<10;i++)
if(e.getActionCommand().equals(String.valueOf(i)))
if(toggle==false)
{tf.setText(String.valueOf(i));toggle=true;}
else
tf.setText(tf.getText()+i);
if(e.getActionCommand().equals("."))
if(toggle==false)
{tf.setText(".");toggle=true;}
else
tf.setText(tf.getText()+".");
if(e.getActionCommand().equals("+")||e.getActionCommand().equals("-")||e.getActionCommand().equals("*")||e.getActionCommand().equals("/"))
{
a=(Float.valueOf(tf.getText())).floatValue();
toggle=false;
//tf.setText("");
if(e.getActionCommand().equals("+"))
    type=1;
if(e.getActionCommand().equals("-"))
        type=2;
if(e.getActionCommand().equals("*"))
type=3;
if(e.getActionCommand().equals("/"))
type=4;
}
if(e.getActionCommand().equals("="))
{
//tf.setText("");
b=(Float.valueOf(tf.getText())).floatValue();
            tf.setText("");
if(type==1)
    result=a+b;
if(type==2)
result=a-b;
if(type==3)
result=a*b;
if(type==4)
result=a/b;
tf.setText(String.valueOf(result));
repaint();
type=0;/**/
toggle=false;
}
if(e.getSource()==b_c)
//if(e.getSourse(" Clear "))
tf.setText("");
if(e.getSource()==b_e)
//if(e.getActionCommand().equals("  Exit  "))
System.exit(0);
}
}