[英]While loop does not exit
While trying to write a simple java code to replace a particular character in a given string by using loop I have been much confused to find the mistake. 在尝试编写简单的Java代码以使用循环替换给定字符串中的特定字符时,我很困惑地发现了错误。 Details are as below:
详细信息如下:
INPUT String : "123qq11 1q1 11q1 1qq11 1q1 11q1"
REQUIRED OUTPUT: "123QQ11 1Q1 11Q1 1QQ11 1Q1 11Q1"
GOT OUTPUT: "Q23QQ11 1Q1 11Q1 1QQ11 1Q1 11Q1" as infinite loop
ALGORITHM: Replacing 'q' by 'Q' in given String. 算法:在给定的字符串中用“ Q”替换“ q”。
My code to be corrected is: 我要更正的代码是:
public class Rani {
public static void main(String[] args) {
StringBuilder sb = new StringBuilder("123qq11 1q1 11q1 1qq11 1q1 11q1");
int j = 0;
int i = 0;
while (i < sb.length()) {
while (i + 1 < sb.length()) { // while 2nd
i++;
if (sb.charAt(i) == 'q') {
j = i;
break;
} else {
break;
}
}
sb.replace(j, j + 1, "Q");
System.out.println(sb);
}
}
}
Being new comer to java and programming I have been failed to manage the corrections. 作为Java和编程的新手,我无法管理这些更正。
Firstly you don't need 2
while loops. 首先,您不需要
2
while循环。
Secondly i
stays at sb.length() - 1
forever making it an infinite loop. 其次,
i
永远停留在sb.length() - 1
上,从而使其成为无限循环。
You could use a replace
or replaceAll
instead. 您可以使用
replace
或replaceAll
代替。
String st = "123qq11 1q1 11q1 1qq11 1q1 11q1"
st = st.replace("q", "Q");
If you want to do it with while loops. 如果您想用while循环来做。
int i = 0;
while(i < sb.length())
{
if(sb.charAt(i) == 'q')
sb.setCharAt(i, 'Q');
i++;
}
Here is the working code 这是工作代码
public static void main(String[] args) {
StringBuilder sb = new StringBuilder("123qq11 1q1 11q1 1qq11 1q1 11q1");
int j = 0;
int i = 0;
while (i < sb.length()) {
while (i < sb.length()) { // while 2nd
if (sb.charAt(i) == 'q') {
j = i;
break;
}
i++;
}
sb.replace(j, j + 1, "Q");
System.out.println(sb);
}
}
Output: 123QQ11 1Q1 11Q1 1QQ11 1Q1 11Q1 输出:123QQ11 1Q1 11Q1 1QQ11 1Q1 11Q1
If you don't want to use replace you can just do this. 如果您不想使用replace,则可以执行此操作。
for (int i = 0; i < st.length(); i++)
if (st.charAt(i) == 'q')
st.setCharAt(i, 'Q');
public static void main (String[] args) {
StringBuilder sb = new StringBuilder("123qq11 1q1 11q1 1qq11 1q1 11q1");
String strnew = "";
for(int i=0;i<sb.length();i++)
{
if(sb.charAt(i)=='q')
{
strnew=strnew+"Q";
}
else
strnew=strnew+sb.charAt(i);
}
System.out.println(strnew);
}
in your code you are telling i to increment too soon. 在您的代码中,您告诉我过快增加。 in the inner loop
i
only gets to 30 while the length is actually 31. if you move the i++
to the end of the first loop but our side of the inner loop it should work they way you want. 在内部循环中,
i
只能达到30,而长度实际上是31。如果将i++
移到第一个循环的末尾,但在我们内部循环的那一侧,它应该按您想要的方式工作。 like so: 像这样:
...
if (sb.charAt(i) == 'q') {
j = i;
break;
}
i++;
}
...
the only problem with that is you are always replacing the first character of the string. 唯一的问题是您总是替换字符串的第一个字符。 the first number "1" is being replaced with a "Q".
第一个数字“ 1”被替换为“ Q”。 becasue you are using
j
to replace "q" it is always the character at the 0th slot. 因为您使用
j
代替“ q”,所以它始终是第0个字符。
You could even make it simpler buy just using one loop: 您甚至可以只使用一个循环就可以使购买更简单:
while (i<sb.length()){
if (sb.charAt(i) == 'q'){
sb.replace(i, i + 1, "Q");
}
i++;
}
System.out.println(sb);
or you could use a for loop: 或者您可以使用for循环:
for (i =0; i<sb.length();i++){
if (sb.charAt(i)=='q'){
sb.replace(i, i+1, "Q");
}
}
System.out.println(sb);
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