[英]Why does my program give an error when reading from file?
從文本文件讀取時,似乎遇到了錯誤。 該程序應讀取一行,檢查第一個字符,然后在if語句中運行相關代碼。 程序在第一行運行良好,並輸出內容,但是無法處理下一行。 這是即時通訊使用的代碼:
public void importStart(){
try {
FileReader fr = new FileReader("src/data.txt");
BufferedReader reader = new BufferedReader(fr);
String line = reader.readLine();
Scanner scan = null;
while(line != null){
scan = new Scanner(line);
String string1 = scan.next();
inputType = string1.charAt(0);
if(inputType == 'S'){
foxCount = scan.nextInt();
rabbitCount = scan.nextInt();
dragonCount = scan.nextInt();
System.out.println(inputType + " "+ foxCount + " "+ rabbitCount + " "+ dragonCount);
}
else if(inputType == 'X'){
System.out.println("Test 1");
animalType = string1.substring(2, 3);
System.out.println("Test 2");
if(animalType == "F"){
step = scan.nextInt();
}
else if(animalType == "R"){
step = scan.nextInt();
}
else if(animalType == "D"){
step = scan.nextInt();
}
System.out.println(inputType + " "+ animalType + " " + step);
}
line = reader.readLine();
}
reader.close();
}
我收到這個錯誤
注意,第一行是應該在此處輸出的,這就是我知道它在第一行上正確運行的方式。 “測試1”也正確顯示,這使我相信問題出在我的string1.substring實現上。 這是問題嗎?
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Exception in thread "AWT-EventQueue-0" java.lang.StringIndexOutOfBoundsException: String index out of range: 3
Test 1
at java.lang.String.substring(Unknown Source)
at DataDisplayGui.importStart(DataDisplayGui.java:107)
at DataDisplayGui.actionPerformed(DataDisplayGui.java:178)
at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
at java.awt.Component.processMouseEvent(Unknown Source)
at javax.swing.JComponent.processMouseEvent(Unknown Source)
at java.awt.Component.processEvent(Unknown Source)
at java.awt.Container.processEvent(Unknown Source)
at java.awt.Component.dispatchEventImpl(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
at java.awt.Container.dispatchEventImpl(Unknown Source)
at java.awt.Window.dispatchEventImpl(Unknown Source)
at java.awt.Component.dispatchEvent(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.awt.EventQueue$3.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.awt.EventQueue$4.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
String string1 = scan.next();
scan.next()在line變量中給您下一個標記,它可能不是整行。 嘗試將有問題的子字符串行替換為:
animalType = line.substring(2, 3);
取決於src / data.txt文件中的內容。 如果您讀的那行是
X
您會收到此錯誤,因為該語句
string1.substring(2,3)
正在嘗試返回從字符2開始的子字符串
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