String1

//【例4.1】常量串的基本操作。

package dataStructure.linearList;
public final class String1
{
private final char[] value; //字符数组，私有最终变量，只能赋值一次
public String1() //构造一个空串
{
this.value = new char[0];
}
public String1(char[] value) //以字符数组构造串对象
{
this.value = new char[value.length]; //当value==null时，Java抛出空对象异常
for (int i=0; i<value.length; i++) //复制数组
this.value[i] = value[i];
}
public String1(String1 str) //拷贝构造方法，复制对象
{
this(str.value);
}
public String1(ng.String Original)
{this.value=Original.toCharArray();
}
public int length() //返回字符串的长度
{
return this.value.length;
}
public char charAt(int index) //返回串中序号为index的字符
{
if (index<0 || index >= this.value.length)
throw new StringIndexOutOfBoundsException(index);//抛出字符串索引越界异常return this.value[index];
}
public String toString()
{
return new String(this.value); //ng.String实现为return this;
}
public String1 concat(String1 str) //返回当前串与指定串str连接生成的新串{ //不改变当前串
if (str==null || str.length()==0) //欲连接的串为空时，返回当前串return this;
char[] buffer = new char[this.value.length + str.length()];
int i;
for (i=0; i<this.value.length; i++) //复制当前串
buffer[i] = this.value[i];
for (int j=0; j<str.value.length; j++) //复制指定串str
buffer[i+j] = str.value[j];
return new String1(buffer);
}
public String1 substring(int begin, int end) //返回串中序号从begin至end-1的子串{
if (begin < 0)
throw new StringIndexOutOfBoundsException(begin);
if (end > value.length)
throw new StringIndexOutOfBoundsException(end);
if (begin > end)
throw new StringIndexOutOfBoundsException(end - begin);
if (begin==0 && end == value.length)
return this;
else
{
char[] buffer = new char[end - begin];
for (int i=0; i< buffer.length; i++) //复制子串
buffer[i] = this.value[i+begin];
return new String1(buffer);
}
}
public String1 substring(int begin) //返回串中序号从begin至串尾的子串{
return substring(begin, value.length);
}
public String1 insert(int index, String1 str) //在source串的index处插入str
{ //返回插入后的串，source串不变char[] buffer = new char[this.value.length + str.length()];
for (int i=0; i< index; i++) //复制子串
buffer[i] = this.value[i];
for (int j=0; j< str.length(); j++) //复制子串
buffer[index+j] = str.charAt(j);
for (int k=index; k< this.value.length; k++) //复制子串
buffer[str.length()+k] = this.value[k];
return new String1(buffer);
}
public String1 delete(int begin, int end) //删除source串中从begin到end-1处的子串{ //返回删除后的串，source串不变char[] buffer = new char[this.value.length-end+begin];
for (int i=0; i< begin; i++) //复制子串
buffer[i] = this.value[i];
for (int k=end; k< this.value.length; k++) //复制子串
buffer[begin+k-end] = this.value[k];
return new String1(buffer);
}
public char[] getValue() {
return value;
}
}。