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java字符串转字符串数组
Java String array is used to hold fixed number of Strings. is very common in , specially among beginners to java and to test some specific scenarios. Even argument is string array – public static void main(String[] args)
. So today we will look into different aspects of java string array with example programs.
Java String数组用于保存固定数量的String。 在非常常见,特别是在Java初学者和测试某些特定情况的初学者中。 甚至参数也是字符串数组– public static void main(String[] args)
。 因此,今天我们将通过示例程序研究java字符串数组的不同方面。
Let’s go over java string array example programs now.
现在让我们来看一下Java字符串数组示例程序。
Below code snippet shows different ways for string array declaration in java.
下面的代码片段显示了Java中字符串数组声明的不同方法。
String[] strArray; //declare without sizeString[] strArray1 = new String[3]; //declare with size
Note that we can also write string array as String strArray[]
but above shows way is the standard and recommended way. Also in the above code, strArray
is null
whereas strArray1
value is [null, null, null]
.
请注意,我们也可以将字符串数组编写为String strArray[]
但以上所示的方法是标准和推荐的方法。 同样在上面的代码中, strArray
为null
而strArray1
值为[null, null, null]
。
Let’s look at different ways to initialize string array in java.
让我们看看在Java中初始化字符串数组的不同方法。
//inline initializationString[] strArray1 = new String[] {"A","B","C"};String[] strArray2 = {"A","B","C"}; //initialization after declarationString[] strArray3 = new String[3];strArray3[0] = "A";strArray3[1] = "B";strArray3[2] = "C";
All the three string arrays will have same values. However if you will call equals
method on them, it will return false.
三个字符串数组都将具有相同的值。 但是,如果您将对它们调用equals
方法,它将返回false。
System.out.println(strArray1.equals(strArray2)); // falseSystem.out.println(Arrays.toString(strArray1).equals(Arrays.toString(strArray2)));// true
The reason is that array are Objects and Object class implements equals() method like below.
原因是数组是Objects,而Object类实现了equals()方法,如下所示。
public boolean equals(Object obj) { return (this == obj); }
Second statement is true because when converted to String, their values are same and String class equals() method implementation check for values. For more details, please check String class API documentation.
第二条语句是正确的,因为当转换为String时,它们的值是相同的,并且String类equals()方法实现会检查值。 有关更多详细信息,请查看String类API文档。
We can iterate over string array using or loop.
我们可以使用或循环遍历字符串数组。
String[] strArray2 = {"A","B","C"}; for (int i = 0; i < strArray2.length; i++) { System.out.print(strArray2[i]);}for (String str : strArray2) { System.out.print(str);}
We can use for loop to search for an string in the array, below is a simple example for that.
我们可以使用for循环在数组中搜索一个字符串,下面是一个简单的例子。
package com.journaldev.stringarray;public class JavaStringArrayExample { public static void main(String[] args) { String[] strArray = { "A", "B", "C" }; boolean found = false; int index = 0; String s = "B"; for (int i = 0; i < strArray.length; i++) { if(s.equals(strArray[i])) { index = i; found = true; break; } } if(found) System.out.println(s +" found at index "+index); else System.out.println(s +" not found in the array"); }}
Notice the use of keyword to get out of the loop as soon as we found the string.
注意,一旦找到字符串,就使用关键字退出循环。
We can implement our own sorting algorithm, or we can use class sorting method.
我们可以实现自己的排序算法,也可以使用类的排序方法。
String[] vowels = {"a","i","u","e","o"}; System.out.println("Before sorting "+Arrays.toString(vowels));Arrays.sort(vowels); System.out.println("After sorting "+Arrays.toString(vowels));
Output of above code snippet will be:
上面的代码片段的输出将是:
Before sorting [a, i, u, e, o]After sorting [a, e, i, o, u]
Note that String implements Comparable interface, so it works for natural sorting. Incase you want to sort by some other way, you can use Arrays.sort()
overloaded method by passing a Comparator. Learn about these sorting techniques at .
请注意,String实现了Comparable接口,因此适用于自然排序。 如果要通过其他方式排序,则可以通过传递Comparator来使用Arrays.sort()
重载方法。 中的了解有关这些排序技术的信息。
We can convert String to string array using it’s split()
method. It’s useful when you get a single string as input with values separated using delimiter character.
我们可以使用它的split()
方法将String转换为字符串数组。 当您获得单个字符串作为输入,并且使用定界符将值分隔开时,这很有用。
String str = "a,e,i,o,u";String[] vowels = str.split(",");System.out.println(Arrays.toString(vowels)); //[a, e, i, o, u]
We can use Arrays.toString()
method to convert String array to String. Note that array doesn’t implement toString()
method, so if you will try to get it’s string representation then you will have to rely on Arrays class, or else write your own custom code.
我们可以使用Arrays.toString()
方法将String数组转换为String。 请注意,array不实现toString()
方法,因此,如果您尝试获取它的字符串表示形式,则必须依赖Arrays类,或者编写自己的自定义代码。
String[] vowels = { "a", "e", "i", "o", "u" };System.out.println(vowels);System.out.println(Arrays.toString(vowels));
Output will be like below.
输出将如下所示。
[Ljava.lang.String;@3d04a311[a, e, i, o, u]
The first output is because of Object class toString() implementation like below.
第一个输出是由于如下所示的Object类toString()实现。
public String toString() { return getClass().getName() + "@" + Integer.toHexString(hashCode()); }
We can get a list representation of string array using Arrays.toList()
method. Note that this list is backed by the array and any structural modification will result in java.lang.UnsupportedOperationException
.
我们可以使用Arrays.toList()
方法获得字符串数组的列表表示形式。 请注意,此列表由数组支持,任何结构修改都会导致java.lang.UnsupportedOperationException
。
String[] vowels = { "a", "e", "i", "o", "u", "a", "o" };ListvowelsList = Arrays.asList(vowels);System.out.println("vowelsList = "+vowelsList);//vowelsList.add("x"); //java.lang.UnsupportedOperationExceptionvowelsList.set(0, "x"); //allowed because no structural modificationSystem.out.println("vowelsList = "+vowelsList);
That’s all for java string array.
Java字符串数组就这些了。
Reference:
参考:
翻译自:
java字符串转字符串数组
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