java - 使用 int 变量更新字符串

Question

我有一个字符串 2.0.0.3 和一个 int 值 4

像 2.0.0.4 这样更新字符串的最简单方法是什么。

尝试使用StringBuilder和chatAt

StringBuilder myName = new StringBuilder(name);
myName.setCharAt(3,(char) value);

但是 myname 的 sysout 给出了一个正方形而不是 2004。

Answer 1

它应该是这样的

StringBuilder myName = new StringBuilder(name); myName.setCharAt(6,(char) ('0'+value));

（顺便说一句，这是一种相当糟糕的风格，我相信其他人会提出更清洁的解决方案。）

Answer 2

尝试

char replacementChar = (char) ('0' + value);
StringBuilder myName = new StringBuilder(name);
myName.setCharAt(6,replacementChar);

但是，我可以建议使用不同的技术来更新该字符串吗？

使用一个类对其进行建模并完全通过实现 toString() 来构建它应该更明智。

public class Version {
    private final static String SEPARATOR = ".";//Note separator could be a field instead of a contant
    private int major;
    private int minor;
    private int incremental;
    private int buildVersion;

    public Version(int major, int minor, int incremental, int buildVersion) {
        this.major = major;
        this.minor = minor;
        this.incremental = incremental;
        this.buildVersion = buildVersion;
    }
    /**
     * Populates this class from String
     * @param version a version number made of numbers separated by a dot
     */
    public Version(String version) {
        if(version != null){
            String[] numbers = version.split("\\" + SEPARATOR);
            if(numbers.length>0) major = toInt(numbers[0]);
            if(numbers.length>1) minor = toInt(numbers[1]);
            if(numbers.length>2) incremental = toInt(numbers[2]);
            if(numbers.length>3) buildVersion = toInt(numbers[3]);
        }
    }
    private int toInt(String strVal){
        int val = 0;
        try {
            val = Integer.parseInt(strVal);
        } catch (NumberFormatException ex) {
            // TODO replace this, please
            ex.printStackTrace();
        }
        return val;
    }
    /**
     * @return the major
     */
    public int getMajor() {
        return major;
    }
    /**
     * @param major the major to set
     */
    public void setMajor(int major) {
        this.major = major;
    }
    /**
     * @return the minor
     */
    public int getMinor() {
        return minor;
    }
    /**
     * @param minor the minor to set
     */
    public void setMinor(int minor) {
        this.minor = minor;
    }
    /**
     * @return the incremental
     */
    public int getIncremental() {
        return incremental;
    }
    /**
     * @param incremental the incremental to set
     */
    public void setIncremental(int incremental) {
        this.incremental = incremental;
    }
    /**
     * @return the buildVersion
     */
    public int getBuildVersion() {
        return buildVersion;
    }
    /**
     * @param buildVersion the buildVersion to set
     */
    public void setBuildVersion(int buildVersion) {
        this.buildVersion = buildVersion;
    }
    /**
     * @see java.lang.Object#toString()
     */
    @Override
    public String toString() {
        return major + SEPARATOR + minor + SEPARATOR + incremental + SEPARATOR + buildVersion;
    }
}

这个类可以这样使用：

Version version = new Version("2.0.0.3");//could be new Version(2, 0, 0, 3)
version.setBuildVersion(4);
System.out.println(version);