Question

我无法找到关于此例外的答案。该程序非常简单，但我不知道为什么不正确。

/**
 * Program selects the first word from the sentence "Hello, my dear!" with
 * the String Classes's methods this.indexOf() and this.substring()  
 * 
 *
 * Last modify: 29th October 2015
 */

public class TakeSubstringWanted {

    public static void main(String[] args) {

        String sentence = "Hello, my dear!";
        String reference = "Hello";

        System.out.println("The sentence is: " + sentence);
        System.out.println("You want to take the first word of that sentence");
        System.out.println("Give me a second...");

        int firstReference = sentence.indexOf(reference);
        int firstLength = reference.length();
        System.out.println("The first reference of the searched word is " + firstReference);
        System.out.println("The first word of the sentence " + sentence + " is: " + "\"" + sentence.substring(firstReference, firstLength) + "\"");
        int secondReference = sentence.indexOf("my");
        System.out.println("The second reference of the searched word is " + secondReference);
        int secondLength = "my".length();
        System.out.println(secondLength);
        System.out.println(sentence);
        System.out.println("The second word of the sentence " + sentence + " is: " + "\"" + sentence.substring(secondReference, secondLength) + "\"");
    }

}

Answer 1

你的问题在最后一行：

System.out.println("The second word of the sentence " + sentence + " is: "
             + "\"" + sentence.substring(secondReference, secondLength) + "\"");

因为您的secondReference = 7和secondLength = 2，但是如果您查看substring IndexOutOfBoundsException方法{/ p>}：

public String substring（int beginIndex，                  int endIndex）

返回一个新字符串，该字符串是此字符串的子字符串。子字符串从指定的beginIndex开始，并扩展到索引endIndex - 1处的字符。因此子字符串的长度为endIndex-beginIndex。

...

<强>抛出：   IndexOutOfBoundsException - 如果beginIndex或endIndex为负数，如果endIndex大于length（），或者beginIndex大于startIndex

意思是，您要求substring将索引7中的字符串返回到索引2，这会导致sentence.substring(secondReference, secondReference + secondLength)。你可能想做的是：

    <LinearLayout
            android:layout_width="fill_parent"
            android:layout_height="fill_parent"
            android:orientation="vertical"> 

`         
        <include layout="@layout/toolbar"/>

        <FrameLayout
                android:id="@+id/frameLayout"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent"></FrameLayout>
    </LinearLayout>



    <android.support.design.widget.NavigationView
            android:id="@+id/navigation_view"
            android:layout_height="match_parent"
            android:layout_width="wrap_content"
            android:layout_gravity="start"
            app:headerLayout="@layout/header"
            app:menu="@menu/drawer"
            />

</android.support.v4.widget.DrawerLayout>

Answer 2

substring的第二个参数是结束索引，而不是要采用的字符数。

sentence.substring(secondReference, secondLength)

当你运行它时，secondLength是2（“my”的长度），但secondReference是7，大于2，导致这样的异常。

如果你想要这两个字符，你需要使用：

sentence.substring(secondReference, secondLength+secondReference)

Answer 3

你的最后一个子串从pos 7开始，结束索引是2，这是不可能的。最后一个索引是结束索引，而不是你想要的char的长度

sentence.substring(secondReference, seconfReference+secondLength);

那会是

吗？

Answer 4

你的问题在这里：

sentence.substring(secondReference, secondLength)

你给予长度，但它应该是

sentence.substring(startIndex, endIndex);

希望有所帮助！

Answer 5

当您第二次使用 sentence.substring（）时，substring方法的第二个参数应该大于第一个参数..在您的情况下，第一个参数是7，第二个参数是2。 ..为什么你得到的字符串索引超出范围：-5

Answer 6

您必须提供结束索引，而不是给出长度。 substring方法的工作方式如下：

substring(int beginIndex, int endIndex)

更改

int firstLength = reference.length();
int secondLength = "my".length();

到

int firstLength = sentence.indexOf(",");
int secondLength = sentence.indexOf(" dear");

试试这个：

String sentence = "Hello, my dear!";
String reference = "Hello";

System.out.println("The sentence is: " + sentence);
System.out.println("You want to take the first word of that sentence");
System.out.println("Give me a second...");

int firstReference = sentence.indexOf(reference);
int firstLength = sentence.indexOf(",");

System.out.println("The first reference of the searched word is " + firstReference);
System.out.println("The first word of the sentence " + sentence + " is: " + "\"" + sentence.substring(firstReference, firstLength) + "\"");

int secondReference = sentence.indexOf("my");

System.out.println("The second reference of the searched word is " + secondReference);

int secondLength = sentence.indexOf(" dear");

System.out.println(secondLength);
System.out.println(sentence);
System.out.println("The second word of the sentence " + sentence + " is: " + "\"" + sentence.substring(secondReference, secondLength) + "\"");

StringIndexOutOfBoundsException：字符串索引超出范围

6 个答案: