如何删除字符串串联中的最后一个“&”？

Question

我将在main方法中这样做，首先实例化该类的一个对象，即。

VeggiesAndFruits myVeg1 = new VeggiesAndFruits(AB);
VeggiesAndFruits myVeg2 = new VeggiesAndFruits(A);
System.out.println(myVeg1.getDescription());
System.out.println(myVeg2.getDescription());

代码示例：

public class VeggiesAndFruits
{
String line;

public VeggiesAndFruits(String line)
{
this.line = line;
}

public String getDescription()
    {
        String description = "";

        if(line.contains("A"))
        {
            description += "Apple & ";
        }
        if(line.contains("B"))
        {
            description += "Banana & ";
        }
        if(line.contains("C"))
        {
            description += "Carrot & ";

        return description;
}
}

Answer 1

如果使用Java8+，我建议在这里使用StringJoiner。正如Javadoc所说的，stringjoiner用于构造由分隔符分隔的字符序列。比如,

public String getDescription() {
    StringJoiner sj = new StringJoiner(" & ");

    if (line.contains("A")) {
        sj.add("Apple");
    }
    if (line.contains("B")) {
        sj.add("Banana");
    }
    if (line.contains("C")) {
        sj.add("Carrot");
    }
    return sj.toString();
}

在Java(5+)的早期版本中，您可以使用StringBuilder（和kaya3提到的“glue”）。

public String getDescription() {
    StringBuilder sb = new StringBuilder();
    String glue = "";
    if (line.contains("A")) {
        sb.append("Apple");
        glue = " & ";
    }
    if (line.contains("B")) {
        sb.append(glue);
        sb.append("Banana");
        glue = " & ";
    }
    if (line.contains("C")) {
        sb.append(glue);
        sb.append("Carrot");
    }
    return sb.toString();
}

在Java5之前，您可以使用StringBuffer

public String getDescription() {
    StringBuffer sb = new StringBuffer();
    String glue = "";
    if (line.contains("A")) {
        sb.append("Apple");
        glue = " & ";
    }
    if (line.contains("B")) {
        sb.append(glue);
        sb.append("Banana");
        glue = " & ";
    }
    if (line.contains("C")) {
        sb.append(glue);
        sb.append("Carrot");
    }
    return sb.toString();
}