Question

我试图让我的if语句有单独的写命令，例如bw.write(b + " - " + a +" = " + c + newLine);问题是由于newLine字符串和bw 缓冲区在curley braces内我不能让那些工作。任何想法？

try {                       
    File file = new File("src/written.txt"); 
    if (!file.exists()) {
        file.createNewFile();
    }
    FileWriter fw = new FileWriter(file, true);
    BufferedWriter bw = new BufferedWriter(fw);
    String newLine = System.getProperty("line.separator");
    bw.write(b + " - " + a +" = " + c + newLine);
    bw.close();
} catch (IOException e) {
    e.printStackTrace();
}

JOptionPane.showMessageDialog(null,"Amount Transfered: " + b + " - " + "Previous Balance: " + a +"\nRemaning Balance: " + c);

if( c == 0){
    JOptionPane.showMessageDialog(null,"Transfered granted. Balance empty","Transation successful!",JOptionPane.WARNING_MESSAGE);
}else if (c > 0){
    JOptionPane.showMessageDialog(null,"Transfered granted.","Transation successful!",JOptionPane.INFORMATION_MESSAGE);
}else{
    JOptionPane.showMessageDialog(null,"Transfer denied due to insufficent funds.","Transaction denied!",JOptionPane.ERROR_MESSAGE);
}

Answer 1

我不完全确定你的目标是什么，但看起来你正在失去BufferedWriter bw的范围。

如果你想在目前居住的{}之外使用bw，请声明：

BufferedWriter bw;
try {
.....
bw = new BufferedWriter(fw);
}

这样，在try块之前声明了bw，这使得你可以在整个代码以及try块中使用它。

Java if语句和写行

1 个答案: