Java 程序小问题:有关图形界面和数据类型不兼容的

import java.awt.*;
import java.util.*;
public class cardlayoutdemo{
public static void main(String args[]){
int[] i={1,2,3};
Frame f=new Frame("cardlayout");
CardLayout card=new CardLayout();
f.setLayout(card);
f.setSize(40,50);
f.add(new Button("one"),"c1");
f.add(new Button("two"),"c2");
f.add(new Button("three"),"c3");
try{
System.in.read();}
catch(Exception e){
System.out.println("error");}
switch(i){
case 1:
card.show(f,"c1");
break;
case 2 :
card.show(f,"c2");
break;
case 3 :
card.show(f,"c3");
break;
}
f.setVisible(true);
}
}

//改完啦！直接运行就好使。

import java.awt.*;

public class cardlayoutdemo {
public static void main(String args[]) {

Frame f = new Frame("cardlayout");
CardLayout card = new CardLayout();
f.setLayout(card);
f.setSize(40, 50);
f.add(new Button("one"), "c1");
f.add(new Button("two"), "c2");
f.add(new Button("three"), "c3");
try {
int i=System.in.read();//read()返回的是int型，输入字符的话返回单个字符的ASCII码
char c=(char)i;
switch (c) {
case '1':

card.show(f, "c1");
break;
case '2':
card.show(f, "c2");
break;
case '3':
card.show(f, "c3");
break;
}
f.setVisible(true);
} catch (Exception e) {
System.out.println("error");
}

}
}

import java.awt.*;
import java.util.*;