Android：当有一个空白的editText字段时，我的应用程序崩溃了

我的代码有问题。 当我有一个空白的editText字段时，它会继续崩溃。 这段代码在我的应用程序的设置中并且可以很好地处理数据，但是当有空白字段时它会使程序崩溃。 这是它的代码。 请不要苛刻，因为它是我的第一个Android应用程序。 所以，如果有人知道如何解决空白的编辑文本字段问题，将不胜感激！ （关于如何改进应用程序的任何其他意见将是一个帮助）。

干杯

package com.cleanyet.cyv100fp; import java.io.FileInputStream; import java.io.FileNotFoundException; import java.io.FileOutputStream; import java.io.IOException; import android.app.Activity; import android.content.Context; import android.content.Intent; import android.os.Bundle; import android.view.View; import android.widget.Button; import android.widget.EditText; public class sTasks extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { // TODO Auto-generated method stub super.onCreate(savedInstanceState); setContentView(R.layout.tasks); /*Sets Up the Variables*/ Button done = (Button) findViewById(R.id.done1); EditText t1 = (EditText)findViewById(R.id.tbTask1); EditText t2 = (EditText)findViewById(R.id.tbTask2); EditText t3 = (EditText)findViewById(R.id.tbTask3); EditText t4 = (EditText)findViewById(R.id.tbTask4); EditText t5 = (EditText)findViewById(R.id.tbTask5); String FILENAME1 = "stask1"; String FILENAME2 = "stask2"; String FILENAME3 = "stask3"; String FILENAME4 = "stask4"; String FILENAME5 = "stask5"; String task1 = null; String task2 = null; String task3 = null; String task4 = null; String task5 = null; String edit = "Edit Task"; /*Fixes the Blank Field bug*/ /*Sets up the file input*/ FileInputStream fis = null; /*Gets the tasks set previously*/ /*Task 1 set up*/ try { fis = openFileInput(FILENAME1); byte[] dataArray = new byte[fis.available()]; while (fis.read(dataArray) != -1){ task1 = new String(dataArray); } } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { try { fis.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (task1.toString().length() < 0) { task1.toString(); t1.setText(task1); } else { t1.setText(edit); } /*Task 2 set up*/ try { fis = openFileInput(FILENAME2); byte[] dataArray = new byte[fis.available()]; while (fis.read(dataArray) != -1){ task2 = new String(dataArray); } } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { try { fis.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (task2.toString().length() < 0) { task2.toString(); t2.setText(task2); } else { t2.setText(edit); } /*Task 3 set up*/ try { fis = openFileInput(FILENAME3); byte[] dataArray = new byte[fis.available()]; while (fis.read(dataArray) != -1){ task3 = new String(dataArray); } } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { try { fis.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (task3.toString().length() < 0) { task3.toString(); t3.setText(task3); } else { t3.setText(edit); } /*Task 4 set up*/ try { fis = openFileInput(FILENAME4); byte[] dataArray = new byte[fis.available()]; while (fis.read(dataArray) != -1){ task4 = new String(dataArray); } } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { try { fis.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (task4.toString().length() < 0) { task4.toString(); t4.setText(task4); } else { t4.setText(edit); } /*Task 5 set up*/ try { fis = openFileInput(FILENAME5); byte[] dataArray = new byte[fis.available()]; while (fis.read(dataArray) != -1){ task5 = new String(dataArray); } } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } finally { try { fis.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } if (task5.toString().length() < 0) { task5.toString(); t5.setText(task5); } else { t5.setText(edit); } /*When changes have been made and done is clicked*/ done.setOnClickListener(new View.OnClickListener() { public void onClick(View v) { // TODO Auto-generated method stub /*Sets up the Variables*/ EditText t1 = (EditText)findViewById(R.id.tbTask1); EditText t2 = (EditText)findViewById(R.id.tbTask2); EditText t3 = (EditText)findViewById(R.id.tbTask3); EditText t4 = (EditText)findViewById(R.id.tbTask4); EditText t5 = (EditText)findViewById(R.id.tbTask5); String tasks1 = t1.getText().toString(); String tasks2 = t2.getText().toString(); String tasks3 = t3.getText().toString(); String tasks4 = t4.getText().toString(); String tasks5 = t5.getText().toString(); String FILENAME1 = "stask1"; String FILENAME2 = "stask2"; String FILENAME3 = "stask3"; String FILENAME4 = "stask4"; String FILENAME5 = "stask5"; String task1 = tasks1; String task2 = tasks2; String task3 = tasks3; String task4 = tasks4; String task5 = tasks5; String edit = "Go to settings to make this task."; if (t1 != null){ t1.setText(edit); /*t2.setText(edit); t3.setText(edit); t4.setText(edit); t5.setText(edit);*/ }; /*Put if statement here to catch the empty field*/ /*Makes The Changes to the Tasks*/ try { FileOutputStream fos1 = openFileOutput(FILENAME1, Context.MODE_PRIVATE); fos1.write(task1.getBytes()); fos1.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } try { FileOutputStream fos2 = openFileOutput(FILENAME2, Context.MODE_PRIVATE); fos2.write(task2.getBytes()); fos2.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } try { FileOutputStream fos3 = openFileOutput(FILENAME3, Context.MODE_PRIVATE); fos3.write(task3.getBytes()); fos3.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } try { FileOutputStream fos4 = openFileOutput(FILENAME4, Context.MODE_PRIVATE); fos4.write(task4.getBytes()); fos4.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } try { FileOutputStream fos5 = openFileOutput(FILENAME5, Context.MODE_PRIVATE); fos5.write(task5.getBytes()); fos5.close(); } catch (FileNotFoundException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } startActivity(new Intent("com.checkin.cyv100fp.settings")); } }); } } 

Answer 1

 if (task1.toString().length() < 0) { task1.toString(); t1.setText(task1); } else { t1.setText(edit); } 

以上根本没有任何意义。

首先， task1是一个字符串，所以不需要调用toString()将其转换为一个字符串。

其次，你的条件语句（ if ）正在检查task1的长度是否小于零....考虑一下。

第三，如果它的长度确实小于零，那么再次调用toString() （没有变量来接收不可能的小于零的结果），然后尝试设置t1 EditText的文本。

您的文件读取可能会失败（可能是因为您稍后只在onClick(...)方法中保存字符串）。 因为如果文件读取失败，您的task字符串将为null ，那么您需要在尝试使用它们之前测试null 。

换句话说，你在代码中这样做......

 String task1 = null; 

要修复我在开头附上的代码，请使用......

 if (task1 != null) { t1.setText(task1); } else { t1.setText(edit); } 

...但最重要的是，确保您的文件中包含您需要阅读的字符串。