【发布时间】：2011-08-16 16:59:48
【问题描述】：
我正在尝试创建一个简单的应用程序，它基本上是一个跟踪器，用于跟踪否。大学生每门学科的课程。该应用程序特定于我的大学时间表。这个想法是我有 3 个活动：main.java、Sublist.java 和 editcrap.java。 main.java 充当启动屏幕并启动 Sublist 活动。
在 Sublist 活动中，用户显示的布局显示 (TextView) (Button) (Counter_TextView) 彼此水平显示。其中有 7 个垂直对齐。
点击菜单按钮时：（编辑主题参数）出现，点击后将用户带到 editcrap.java 活动，其中用户输入在相应的 EditText 框中进行，询问每个对应的主题名称（TextView）和总数Sublist 活动中对应于 (Counter_TextView) 的类数。单击“确定”按钮后，数据将传递给子列表活动以进行显示和操作。
完成此操作后，我需要一种存储数据的方法，以便下次打开应用程序时，它会保留其先前的字符串并且不保留。类值。这是我遇到强制关闭错误或不保留数据错误的地方。这是我的代码... cud 有人请告诉我我做错了吗？我为此苦苦挣扎了好几天:)我基本上需要该应用程序来维护2个文件，其中一个文件包含字符串和其他需要读取并显示在Sublist.java活动中的数字，因为我们需要应用程序完成的任何更改用户也会反映到原始文件中
//Sublist.java:
package com.shuaib669.bunkrecord;
import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import android.app.Activity;
import android.content.Context;
import android.content.Intent;
import android.graphics.Color;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
public class Sublist extends Activity{
double[] no_of_classes = new double[7];
int count[]= new int[7];
double cutOff = 0.3;
String[] newText = new String[7];
String[] newNum = new String[7];
String countString = null;
TextView subject[] = new TextView[7];
TextView counter[] = new TextView[7]; //sub11 is counter text view label
Button button[] = new Button[7]; //button1 is the increment button
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
//Assigning Views to objects.
subject[0] = (TextView) findViewById(R.id.textView1);
counter[0] = (TextView) findViewById(R.id.counter1);
button[0] = (Button) findViewById(R.id.button1);
subject[1] = (TextView) findViewById(R.id.textView2);
counter[1] = (TextView) findViewById(R.id.counter2);
button[1] = (Button) findViewById(R.id.button2);
subject[2] = (TextView) findViewById(R.id.textView3);
counter[2] = (TextView) findViewById(R.id.counter3);
button[2] = (Button) findViewById(R.id.button3);
subject[3] = (TextView) findViewById(R.id.textView4);
counter[3] = (TextView) findViewById(R.id.counter4);
button[3] = (Button) findViewById(R.id.button4);
subject[4] = (TextView) findViewById(R.id.textView5);
counter[4] = (TextView) findViewById(R.id.counter5);
button[4] = (Button) findViewById(R.id.button5);
subject[5] = (TextView) findViewById(R.id.textView6);
counter[5] = (TextView) findViewById(R.id.counter6);
button[5] = (Button) findViewById(R.id.button6);
subject[6] = (TextView) findViewById(R.id.textView7);
counter[6] = (TextView) findViewById(R.id.counter7);
button[6] = (Button) findViewById(R.id.button7);
try {
// open the file for reading
DataInputStream in= new DataInputStream(openFileInput(getFilesDir() + "/" + "subject.txt"));
// if file the available for reading
if (in!= null) {
// prepare the file for reading
String line;
int x=0;
// read every line of the file into the line-variable, on line at the time
while(in.readLine() != null) {
// do something with the strings from the file
line=DataInputStream.readUTF(in);
subject[x].setTextColor(Color.BLACK);
subject[x].setText(line);
x+=1;
}
}
// close the file again
in.close();
}
catch (Exception e) {
e.printStackTrace();// do something if the myfilename.txt does not exits
}
button[0].setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
if(count[0]>=(no_of_classes[0]*cutOff)){
counter[0].setTextColor(Color.RED);
countString = "" +(++count[0]); //Convert from int to String to set in your textview::
counter[0].setText(countString);
}
else{
countString = "" +(++count[0]); //Convert from int to String to set in your textview::
counter[0].setText(countString);
}
}
});
button[1].setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
if(count[1]>=(no_of_classes[1]*cutOff)){
counter[1].setTextColor(Color.RED);
countString = "" +(++count[1]); //Convert from int to String to set in your textview::
counter[1].setText(countString);
}
else{
countString = "" +(++count[1]); //Convert from int to String to set in your textview::
counter[1].setText(countString);
}
}
});
button[2].setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
if(count[2]>=(no_of_classes[2]*cutOff)){
counter[2].setTextColor(Color.RED);
countString = "" +(++count[2]); //Convert from int to String to set in your textview::
counter[2].setText(countString);
}
else{
countString = "" +(++count[2]); //Convert from int to String to set in your textview::
counter[2].setText(countString);
}
}
});
button[3].setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
if(count[3]>=(no_of_classes[3]*cutOff)){
counter[3].setTextColor(Color.RED);
countString = "" +(++count[3]); //Convert from int to String to set in your textview::
counter[3].setText(countString);
}
else{
countString = "" +(++count[3]); //Convert from int to String to set in your textview::
counter[3].setText(countString);
}
}
});
button[4].setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
if(count[4]>=(no_of_classes[4]*cutOff)){
counter[4].setTextColor(Color.RED);
countString = "" +(++count[4]); //Convert from int to String to set in your textview::
counter[4].setText(countString);
}
else{
countString = "" +(++count[4]); //Convert from int to String to set in your textview::
counter[4].setText(countString);
}
}
});
button[5].setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
if(count[5]>=(no_of_classes[5]*cutOff)){
counter[5].setTextColor(Color.RED);
countString = "" +(++count[5]); //Convert from int to String to set in your textview::
counter[5].setText(countString);
}
else{
countString = "" +(++count[5]); //Convert from int to String to set in your textview::
counter[5].setText(countString);
}
}
});
button[6].setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
if(count[6]>=(no_of_classes[6]*cutOff)){
counter[6].setTextColor(Color.RED);
countString = "" +(++count[6]); //Convert from int to String to set in your textview::
counter[6].setText(countString);
}
else{
countString = "" +(++count[6]); //Convert from int to String to set in your textview::
counter[6].setText(countString);
}
}
});
}
public boolean onCreateOptionsMenu(Menu menu){ // What the MENU button does.
super.onCreateOptionsMenu(menu);
MenuInflater castle = getMenuInflater();
castle.inflate(R.menu.main_menu, menu);
return(true);
}
public boolean onOptionsItemSelected(MenuItem item){ // Opens Options of MENU.
switch(item.getItemId()){
case R.id.editcrap: startActivityForResult((new Intent("com.shuaib669.bunkrecord.EDITCRAP")), 1);
return(true);
}
return(false);
}
@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
// TODO Auto-generated method stub
super.onActivityResult(requestCode, resultCode, data);
switch(requestCode){
case 1: if(resultCode==Activity.RESULT_OK){
newText = data.getStringArrayExtra("com.shuaib669.bunkrecord.thetext");
newNum = data.getStringArrayExtra("com.shuaib669.bunkrecord.thenum");
try {
// open myfilename.txt for writing
DataOutputStream out = new DataOutputStream(openFileOutput(getFilesDir() + "/" + "subject.txt", Context.MODE_PRIVATE));
//newNum = data.getIntArrayExtra("com.shuaib669.thenum");
//for loop to setText in the TextViews of main.xml
for(int x=0;x<7;x++){
subject[x].setTextColor(Color.BLACK);
subject[x].setText(newText[x]);
// write the contents on mySettings to the file
out.writeUTF(newText[x]);
try{
no_of_classes[x]=Integer.parseInt(newNum[x]);
}
catch(Exception nfe){
nfe.printStackTrace();
}
// close the file
out.close();
}
}
catch (Exception e) {
Log.i("Data Input Sample", "I/O Error"); //do something if an Exception occurs.
}
}
break;
}
}
}
//editcrap.java:
package com.shuaib669.bunkrecord;
import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
public class editcrap extends Activity{
EditText sub[] = new EditText[7]; //list of subject text edit labels.
Button parambutton1; //OK buttons for edit list.
EditText num[] = new EditText[7]; //list of objects of total no. of classes bunked edit text labels. (boinkers i know)
String theText[] = new String[7];
String theNum[] = new String[7];
@Override
protected void onCreate(Bundle savedInstanceState) {
// TODO Auto-generated method stub
super.onCreate(savedInstanceState);
setContentView(R.layout.params);
sub[0] = (EditText) findViewById(R.id.peditText1); //pedittext is the parameter menu edit text label
num[0] = (EditText) findViewById(R.id.pnumText1); //EditText label for takin in total no. of classes for 1 subject
sub[1] = (EditText) findViewById(R.id.peditText2);
num[1] = (EditText) findViewById(R.id.pnumText2);
sub[2] = (EditText) findViewById(R.id.peditText3);
num[2] = (EditText) findViewById(R.id.pnumText3);
sub[3] = (EditText) findViewById(R.id.peditText4);
num[3] = (EditText) findViewById(R.id.pnumText4);
sub[4] = (EditText) findViewById(R.id.peditText5);
num[4] = (EditText) findViewById(R.id.pnumText5);
sub[5] = (EditText) findViewById(R.id.peditText6);
num[5] = (EditText) findViewById(R.id.pnumText6);
sub[6] = (EditText) findViewById(R.id.peditText7);
num[6] = (EditText) findViewById(R.id.pnumText7);
parambutton1 = (Button) findViewById(R.id.parambutton1); //pbutton1 is the ok button to accept the input.
parambutton1.setOnClickListener(new View.OnClickListener() {
public void onClick(View v) {
// TODO Auto-generated method stub
for(int x=0;x<7;x++){
theText[x] = sub[x].getText().toString();
theNum[x] = num[x].getText().toString();
//theNum[x] = Integer.parseInt(num[x].getText().toString());
}
Intent data = new Intent(editcrap.this, Sublist.class);
data.putExtra("com.shuaib669.bunkrecord.thetext", theText);
data.putExtra("com.shuaib669.bunkrecord.thenum", theNum);
setResult(Activity.RESULT_OK, data);
finish();
}
});
}
}
【问题讨论】：
-
为什么不使用共享首选项？
-
为什么不使用 SQLite 数据库。或者你可以做一个 SharedPreference，看起来就是这样。
-
好的，我会这样做...:)...感谢您的建议 :)
-
这只是比将它们放入文件要容易得多，SharedPreferences 可以采用原语（int，bool，String）并将它们保存在一个名称下，因此您知道哪些是哪些。
-
我无法理解共享首选项及其相关方法的工作原理......使用共享首选项保存和检索数据的重要步骤是什么？
标签： android android-layout android-emulator android-manifest