java中的FileWriter用於建立文件，可以寫入字元到建立的文件中；輸出流類別是FileWriter 類別的基類，因為它是從FileWriter 類別繼承的，並且該類別的建構子所做的假設是，如果要由我們指定這些值，則允許預設字元編碼和預設位元組緩衝區大小。輸出流編寫器必須在檔案輸出流上建構。
Java FileWriter 類別聲明：
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Java.lang.Object Java.io.Writer Java.io.OutputStreamWriter Java.io.FileWriter
java中的FileWriter類別由多個建構子組成。他們是：
java中的FileWriter類別由幾個方法組成，分別是：
以下是用Java實作FileWriter的範例：
示範 FileWriter 類別所建立的 Java 程式。
代碼：
import java.io.*;
public class Read {
public static void main(String args[])throws IOException {
File file1 = new File("check.txt");
// A file is created
file1.createNewFile();
// Object of FileWriter is created
FileWriter writer1 = new FileWriter(file1);
// Contents are written to the file
writer1.write("Welcome to FileWriter");
writer1.flush();
writer1.close();
// Object of filereader is created
FileReader read = new FileReader(file1);
char [] a1 = new char[50];
read.read(a1); // array contents are read
for(char ch : a1)
System.out.print(ch); // characters are printed one by one
read.close();
}
}輸出：
使用 FileWriter 類別建立文字檔案的 Java 程式。
代碼：
import java.io.*;
public class Example {
public static void main(String[] args) {
//File constructor is initialized
File file1 = new File("C:/Users/shivakumarsh/Desktop/Learning/source.txt");
try {
boolean create = file1.createNewFile();
if (create) {
System.out.println("File creation is succesful.");
}else {
System.out.println("There is already a file by this name.");
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
Java 程式示範將字串附加到文件末尾。
代碼：
import java.io.*;
public class Example {
public static void append(String fileName,
String string)
{
try {
// The file is opened in append mode
BufferedWriter out1 = new BufferedWriter(
new FileWriter(fileName, true));
out1.write(string);
out1.close();
}
catch (IOException e) {
System.out.println("occurance of exception" + e);
}
}
public static void main(String[] args)
throws Exception
{
// A sample file is created with some text containing in it
String fileName = "Shobha.txt";
try {
BufferedWriter out1 = new BufferedWriter(
new FileWriter(fileName));
out1.write("Learning appending\n");
out1.close();
}
catch (IOException e) {
System.out.println("occurance of exception" + e);
}
// The newly created file is appended with the string value passed here
String string = "Learning is good";
append(fileName, string);
// contents of the modified file are printed here
try {
BufferedReader in1 = new BufferedReader(
new FileReader("Shobha.txt"));
String mystr;
while ((mystr = in1.readLine()) != null) {
System.out.println(mystr);
}
}
catch (IOException e) {
System.out.println("Occurance of exception" + e);
}
}
}輸出：
Java 程式使用 FileWriter 逐行寫入檔案。
代碼：
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.util.ArrayList;
import java.util.List;
public class List {
public static void main(String[] args) throws Exception {
ArrayList<String> list1 = new ArrayList<String>();
// The newly created file is appended with the string value passed here
list1.add("Understanding an example in java");
list1.add("second line of the file");
list1.add("third line of the file");
writeFile("C:/Users/shivakumarsh/Desktop/Learning/source.txt", list1);
System.out.println("file creation is successful");
}
public static void write(String fileName, List<String> list1) throws Exception {
FileWriter fwd = null;
BufferedWriter bwd = null;
try {
fwd = new BufferedWriter(fwd);
for (int j = 0; list1 != null && j < list.size(); j++) {
bwd.write(list.get(j));
bwd.write("\n");
}
} catch (Exception e1) {
System.out.println("error occured:" + e1.getMessage());
throw e1;
} finally {
try {
bwd.close();
} catch (Exception e1) {
}
try {
fwd.close();
} catch (Exception e1) {
}
}
}
}輸出：
在本教程中，我們了解了FileWriter 的概念，如FileWriter 的定義、如何聲明FileWriter、FileWriter 中的構造函數以及編程示例來演示FileWriter 類的創建，使用FileWriter 類創建文本文件，使用FileWriter 類將文字追加到由內容組成的現有文件中，使用FileWriter 類別逐行寫入新文件，即一行一行地新增內容。
這是 Java 中 FileWriter 的指南。這裡我們討論如何宣告 FileWriter、FileWriter 中的建構子及其方法以及程式碼實作。您也可以瀏覽我們其他推薦的文章以了解更多資訊 –
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