有一些简单的方法来填充字符串在Java?
似乎是一些应该在一些stringutil类API,但我找不到任何东西,这样做。
有一些简单的方法来填充字符串在Java?
似乎是一些应该在一些stringutil类API,但我找不到任何东西,这样做。
当前回答
public static String padLeft(String in, int size, char padChar) {
if (in.length() <= size) {
char[] temp = new char[size];
/* Llenado Array con el padChar*/
for(int i =0;i<size;i++){
temp[i]= padChar;
}
int posIniTemp = size-in.length();
for(int i=0;i<in.length();i++){
temp[posIniTemp]=in.charAt(i);
posIniTemp++;
}
return new String(temp);
}
return "";
}
其他回答
为此编写自己的函数可能比其他答案更简单。
private static String padRight(String str, String padChar, int n) {
String paddedString = str;
while (paddedString.length() < n) {
paddedString = padChar + str;
}
return paddedString;
}
private static String padLeft(String str, String padChar, int n) {
String paddedString = str;
while (paddedString.length() < n) {
paddedString += padChar;
}
return paddedString;
}
从Java 1.5开始,string. format()可以用于左/右填充给定的字符串。
public static String padRight(String s, int n) {
return String.format("%-" + n + "s", s);
}
public static String padLeft(String s, int n) {
return String.format("%" + n + "s", s);
}
...
public static void main(String args[]) throws Exception {
System.out.println(padRight("Howto", 20) + "*");
System.out.println(padLeft("Howto", 20) + "*");
}
输出为:
Howto *
Howto*
简单的东西:
该值应该是字符串。如果不是,就转换成字符串。比如"" + 123或Integer.toString(123)
// let's assume value holds the String we want to pad
String value = "123";
子字符串从值length char索引开始,直到填充的结束长度:
String padded="00000000".substring(value.length()) + value;
// now padded is "00000123"
更精确的
垫:
String padded = value + ("ABCDEFGH".substring(value.length()));
// now padded is "123DEFGH"
垫左:
String padString = "ABCDEFGH";
String padded = (padString.substring(0, padString.length() - value.length())) + value;
// now padded is "ABCDE123"
在番石榴中,这很简单:
Strings.padStart("string", 10, ' ');
Strings.padEnd("string", 10, ' ');
不管怎样,我一直在寻找一些可以填充的东西,然后我决定自己编写代码。它非常简洁,你可以很容易地从中推导出padLeft和padRight
/**
* Pads around a string, both left and right using pad as the template, aligning to the right or left as indicated.
* @param a the string to pad on both left and right
* @param pad the template to pad with, it can be of any size
* @param width the fixed width to output
* @param alignRight if true, when the input string is of odd length, adds an extra pad char to the left, so values are right aligned
* otherwise add an extra pad char to the right. When the input is of even length no extra chars will be inserted
* @return the input param a padded around.
*/
public static String padAround(String a, String pad, int width, boolean alignRight) {
if (pad.length() == 0)
throw new IllegalArgumentException("Pad cannot be an empty string!");
int delta = width - a.length();
if (delta < 1)
return a;
int half = delta / 2;
int remainder = delta % 2;
String padding = pad.repeat(((half+remainder)/pad.length()+1)); // repeating the padding to occupy all possible space
StringBuilder sb = new StringBuilder(width);
// sb.append( padding.substring(0,half + (alignRight ? 0 : remainder)));
sb.append(padding, 0, half + (alignRight ? 0 : remainder));
sb.append(a);
// sb.append( padding.substring(0,half + (alignRight ? remainder : 0)));
sb.append(padding, 0, half + (alignRight ? remainder : 0));
return sb.toString();
}
虽然它应该是相当快的,它可能会受益于使用一些韵母在这里和那里。