public class StringEnd02 {
public static void main(String argsp[])
{
String mail = "[email protected]";
String mail2 = "123456#gmail,com";
String[] bx = new String[3];
bx[0] = "@";
bx[1] = ".";
System.out.println(mail);
for (int i = 0 ; i <=bx.length;i++)
{
System.out.println("mail里是否包含"+bx[i]+"\t--->"+mail.contains(bx[i]));
} }}
执行后有判断结果,但会报错。请教为什么?
[email protected]
mail里是否包含@ --->true
mail里是否包含. --->true
Exception in thread "main" java.lang.NullPointerException
at java.lang.String.contains(Unknown Source)
at StringEnd02.main(StringEnd02.java:13)
另外,我不知道如何在写一个for来判断mail2
求教各位。。
public static void main(String argsp[])
{
String mail = "[email protected]";
String mail2 = "123456#gmail,com";
String[] bx = new String[3];
bx[0] = "@";
bx[1] = ".";
System.out.println(mail);
for (int i = 0 ; i <=bx.length;i++)
{
System.out.println("mail里是否包含"+bx[i]+"\t--->"+mail.contains(bx[i]));
} }}
执行后有判断结果,但会报错。请教为什么?
[email protected]
mail里是否包含@ --->true
mail里是否包含. --->true
Exception in thread "main" java.lang.NullPointerException
at java.lang.String.contains(Unknown Source)
at StringEnd02.main(StringEnd02.java:13)
另外,我不知道如何在写一个for来判断mail2
求教各位。。
for (int i = 0 ; i <=bx.length;i++)
修改为:
for (int i = 0 ; i < bx.length;i++)
String mail = "[email protected]";
String mail2 = "123456#gmail,com";
String[] bx = new String[3];
bx[0] = "@";
bx[1] = ".";
System.out.println(mail);
for (int i = 0; i < (bx.length-1); i++) {
System.out.println("mail里是否包含" + bx[i] + "\t--->"+ mail.contains(bx[i]));
}
}
这样的话就不会报错了
你这样做的话数组是不越界了,但是他的数组里有个“null”,所以说应该还会报错
public class StringEnd02 {
public static void main(String argsp[])
{
String mail = "[email protected]";
String mail2 = "123456#gmail,com";
String[] bx = new String[2];
bx[0] = "@";
bx[1] = ".";
System.out.println(mail);
for (int i = 0 ; i <bx.length;i++)
{
System.out.println("mail里是否包含"+bx[i]+"\t--->"+mail.contains(bx[i]));
} }}
代码我给你贴出来,但还是希望你能自己去做,不要去复制我的代码,参考一下就可以了。
希望对你有帮助
public static void main(String argsp[]) {
String mail = "[email protected]";
String mail2 = "123456#gmail,com";
String[] bx = new String[4];
bx[0] = "@";
bx[1] = ".";
bx[2] = "#";
bx[3] = ",";
System.out.println(mail);
for (int i = 0; i <bx.length; i++) {
System.out.println("mail 里是否包含" + bx[i] + "\t--->"+ mail.contains(bx[i]));
System.out.println("mail2 里是否包含" + bx[i] + "\t--->"+ mail2.contains(bx[i]));
}
}