我想在我的 android 应用程序中开发一个读取功能,以便它可以读取设备中的 csv 文件。这是我的代码:
Button btninsert;
TextView CSV1;
TextView CSV2;
TextView CSV3;
TextView CSV4;
String[][] Data;
int numrecord=0;
@Override
public void onCreate(Bundle savedInstanceState) {
//create the activity
super.onCreate(savedInstanceState);
//set up the layout
setContentView(R.layout.activity_chico);
btninsert = (Button) findViewById(R.id.Insert);
CSV1 = (TextView) findViewById(R.id.CSV1);
CSV2 = (TextView) findViewById(R.id.CSV2);
CSV3 = (TextView) findViewById(R.id.CSV3);
CSV4 = (TextView) findViewById(R.id.CSV4);
if(new File(Environment.getExternalStorageDirectory()+"/Chico/record.csv").exists()){
btninsert.setVisibility(View.VISIBLE);
}else{
btninsert.setVisibility(View.GONE);
}
CSV1.setVisibility(View.GONE);
CSV2.setVisibility(View.GONE);
CSV3.setVisibility(View.GONE);
CSV4.setVisibility(View.GONE);
btninsert.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
// TODO Auto-generated method stub
btninsert.setVisibility(View.GONE);
try {
BufferedReader reader = new BufferedReader(new FileReader(Environment.getExternalStorageDirectory()+"/Chico/record.csv"));
try {
String line;
while ((line = reader.readLine()) != null){
String[] RowData = line.split(",");
Data[numrecord][0]=RowData[0];
Data[numrecord][1]=RowData[1];
Data[numrecord][2]=RowData[2];
Data[numrecord][3]=RowData[3];
numrecord++;
}
} catch (IOException ex) {
}
} catch (FileNotFoundException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
for(int i=0; i<numrecord; i++){
if(i==0){
CSV1.setVisibility(View.VISIBLE);
CSV2.setVisibility(View.VISIBLE);
CSV3.setVisibility(View.VISIBLE);
CSV4.setVisibility(View.VISIBLE);
CSV1.setText(Data[i][0]);
CSV2.setText(Data[i][1]);
CSV3.setText(Data[i][2]);
CSV4.setText(Data[i][3]);
}else{
CSV1.append(" "+Data[i][0]);
CSV2.setText(" "+Data[i][1]);
CSV3.setText(" "+Data[i][2]);
CSV4.setText(" "+Data[i][3]);
}
}
}
});
}
但是,每当我单击该按钮时,系统意外结束,并且错误日志中出现错误消息,其中提到了以下几行出现空指针异常。
Data[numrecord][0]=RowData[0];
Data[numrecord][1]=RowData[1];
Data[numrecord][2]=RowData[2];
Data[numrecord][3]=RowData[3];
有人可以告诉我异常的原因是什么吗?
我的示例 csv 文件包含两行,每行有四列。就像我在下面做的例子一样:
1 1 in 8/6/2012
1 1 out 8/6/2012
如果我在 while 循环中使用以下代码,它可以正常工作:
while ((line = reader.readLine()) != null){
String[] RowData = line.split(",");
if(numrecord==0) {
CSV1.setText(RowData[0]);
CSV2.setText(RowData[1]);
CSV3.setText(RowData[2]);
CSV4.setText(RowData[3]);
} else {
CSV1.append(" "+RowData[0]);
CSV2.append(" "+RowData[1]);
CSV3.append(" "+RowData[2]);
CSV4.append(" "+RowData[3]);
}
numrecord++;
}
这就是为什么我认为问题出在数据数组上