“Android中创建新的PDF页面产生的页面比预期多”

huangapple
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英文:

New PDF page creation in Android is producing more pages than expected

问题

在我的应用程序中，用户可以通过将它们添加为ArrayList的对象来创建PDF的新页面。然后，通过for循环管理新页面的创建，以便迭代ArrayList中的每个对象并将其打印到新页面。

但是，当我打开已创建的PDF时，似乎会得到一个“平方”数量的页面。
例如
我创建2页，得到4页
我创建3页，得到9页
等等

我认为这与我的for循环有关，但我看不出来。有人可以看一下我的代码吗？

public class MainActivity extends AppCompatActivity {

    private EditText firstEditText;
    ArrayList<PDFPageModel> pageModelArrayList = new ArrayList<>();

    @RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        firstEditText = findViewById(R.id.firstEditText);
        //请求权限（我不需要这部分）
        ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, PackageManager.PERMISSION_GRANTED);

        //每次创建时清除数组内存
        pageModelArrayList.clear();
    }

    public void addObjectToList(View view){
        //创建新对象
        PDFPageModel pdfPageModel = new PDFPageModel();

        //从编辑文本中添加内容到对象并设置类型
        pdfPageModel.setPageData(firstEditText.getText().toString().trim());
        pdfPageModel.setType("Text");

        pageModelArrayList.add(pdfPageModel);

        Toast.makeText(MainActivity.this, "Text added", Toast.LENGTH_LONG).show();
    }

    @RequiresApi(api = Build.VERSION_CODES.KITKAT)
    public void createMyPDF(View view){
        //分为3部分完成
        //1. 创建PDF文档，2. 写入文档，3. 保存文档到文件夹

        //1. 创建PDF文档
        PdfDocument pdfDocument = new PdfDocument();

        //2.
        //用于ArrayList新页面的for循环
        for (int i=0; i < pageModelArrayList.size(); i++){
            for(PDFPageModel filledData : pageModelArrayList){
                filledData.getPageData();
                filledData.getType();

                if(filledData.getType().equals("Text")){
                    //创建页面信息描述
                    PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(595, 842, i+1).create();

                    //开始一个页面
                    PdfDocument.Page page = pdfDocument.startPage(pageInfo);

                    //写入新页面
                    Paint paint = new Paint();

                    //用于写入页面的画布，从输入的文本获取对象数据
                    String myString = filledData.getPageData();

                    //设置文本在页面上的起始位置
                    int x = 10, y = 25;

                    //多行循环
                    for(String line:myString.split("\n")){
                        page.getCanvas().drawText(line, x, y, paint);
                        y+=paint.descent()-paint.ascent();
                    }
                    //完成页面
                    pdfDocument.finishPage(page);
                }else {
                    Toast.makeText(MainActivity.this, "Object Type not text", Toast.LENGTH_LONG).show();
                }
            }
        }

        //3. 保存到文件夹
        String myFilePath = String.valueOf(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS));

        String fileName = "/myNewPDF-TEST.pdf";

        //创建要保存在其中的文件夹
        File myFile = new File(myFilePath + "/PDFTestStorage");
        if(!myFile.exists()){
            myFile.mkdirs();
        }

        //新文件
        File file = new File(myFile, fileName);

        //保存文档
        try {
            pdfDocument.writeTo(new FileOutputStream(file));
            Toast.makeText(MainActivity.this, "File Created", Toast.LENGTH_LONG).show();
        } catch (Exception e) {
            e.printStackTrace();
            Toast.makeText(MainActivity.this, "Error: File not created", Toast.LENGTH_LONG).show();
        }

        //关闭PDF文档
        pdfDocument.close();
    }
}

希望这能帮助您解决问题。如果还有其他问题，请随时提出。

英文:

In my app users can create new pages for a PDF by adding them as objects to an ArrayList. The new page creation is then managed by a for loop to iterate through each object in the ArrayList and print it to a new page.

But when I open the PDF that has been created I seem to be getting a 'squared' amount of pages.
e.g
I create 2 pages, I get 4
I create 3 pages, I get 9
etc

I think it has something to do with my for loop but I can't see it. Can someone have a look at my code?

    public class MainActivity extends AppCompatActivity {
private EditText firstEditText;
ArrayList&lt;PDFPageModel&gt; pageModelArrayList = new ArrayList&lt;&gt;();
@RequiresApi(api = Build.VERSION_CODES.JELLY_BEAN)
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
firstEditText = findViewById(R.id.firstEditText);
//request permissions (I won&#39;t need this part)
ActivityCompat.requestPermissions(MainActivity.this, new String[]{Manifest.permission.READ_EXTERNAL_STORAGE, Manifest.permission.WRITE_EXTERNAL_STORAGE}, PackageManager.PERMISSION_GRANTED);
//clear array memory each time you onCreate
pageModelArrayList.clear();
}
public void addObjectToList(View view){
//create new object
PDFPageModel pdfPageModel = new PDFPageModel();
//add stuff to object from edit text and set type
pdfPageModel.setPageData(firstEditText.getText().toString().trim());
pdfPageModel.setType(&quot;Text&quot;);
pageModelArrayList.add(pdfPageModel);
Toast.makeText(MainActivity.this, &quot;Text added&quot;, Toast.LENGTH_LONG).show();
}
@RequiresApi(api = Build.VERSION_CODES.KITKAT)
public void createMyPDF(View view){
//done in 3 parts
//1. creation of PDF document, 2. writing to the document, 3. save document to folder
//1. PDF Document Creation
PdfDocument pdfDocument = new PdfDocument();
//2.
//for loop for ArrayList new page
for (int i=0; i &lt; pageModelArrayList.size(); i++){
for(PDFPageModel filledData : pageModelArrayList){
filledData.getPageData();
filledData.getType();
if(filledData.getType() == &quot;Text&quot;){
//create a page info description
PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(595, 842, i+1).create();
//start a page
PdfDocument.Page page = pdfDocument.startPage(pageInfo);
//writing to new page
Paint paint = new Paint();
//canvas used to write to page, getting object data from inputted text
String myString = filledData.getPageData();
//setting where to start text on the page
int x = 10, y = 25;
//multi line loop
for(String line:myString.split(&quot;\n&quot;)){
page.getCanvas().drawText(line, x, y, paint);
y+=paint.descent()-paint.ascent();
}
//finish page
pdfDocument.finishPage(page);
}else {
Toast.makeText(MainActivity.this, &quot;Object Type not text&quot;, Toast.LENGTH_LONG).show();
}
}
}
//3. saving to folder
String myFilePath = String.valueOf(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS));
String fileName = &quot;/myNewPDF-TEST.pdf&quot;;
//create folder to be saved in
File myFile = new File(myFilePath + &quot;/PDFTestStorage&quot;);
if(!myFile.exists()){
myFile.mkdirs();
}
//new file
File file = new File(myFile, fileName);
//save document
try {
pdfDocument.writeTo(new FileOutputStream(file));
Toast.makeText(MainActivity.this, &quot;File Created&quot;, Toast.LENGTH_LONG).show();
} catch (Exception e) {
e.printStackTrace();
Toast.makeText(MainActivity.this, &quot;Error: File not created&quot;, Toast.LENGTH_LONG).show();
}
//close pdf doc
pdfDocument.close();
}

答案1

得分: 1

Simply removing the outermost for loop, i.e replacing:

for (int i=0; i &lt; pageModelArrayList.size(); i++){
    for(PDFPageModel filledData : pageModelArrayList){
        filledData.getPageData();
        filledData.getType();

        if(filledData.getType() == &quot;Text&quot;){
            //create a page info description
            PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(595, 842, i+1).create();

            //start a page
            PdfDocument.Page page = pdfDocument.startPage(pageInfo);

            //writing to new page
            Paint paint = new Paint();

            //canvas used to write to page, getting object data from inputted text
            String myString = filledData.getPageData();

            //setting where to start text on the page
            int x = 10, y = 25;

            //multi line loop
            for(String line:myString.split(&quot;\n&quot;)){
                page.getCanvas().drawText(line, x, y, paint);
                y+=paint.descent()-paint.ascent();
            }
            //finish page
            pdfDocument.finishPage(page);
        }else {
            Toast.makeText(MainActivity.this, &quot;Object Type not text&quot;, Toast.LENGTH_LONG).show();
        }
    }
}

with:

int i=0;
for(PDFPageModel filledData : pageModelArrayList){
    filledData.getPageData();
    filledData.getType();

    if(filledData.getType() == &quot;Text&quot;){
        //create a page info description
        PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(595, 842, i+1).create();

        //start a page
        PdfDocument.Page page = pdfDocument.startPage(pageInfo);

        //writing to new page
        Paint paint = new Paint();

        //canvas used to write to page, getting object data from inputted text
        String myString = filledData.getPageData();

        //setting where to start text on the page
        int x = 10, y = 25;

        //multi line loop
        for(String line:myString.split(&quot;\n&quot;)){
            page.getCanvas().drawText(line, x, y, paint);
            y+=paint.descent()-paint.ascent();
        }
        //finish page
        pdfDocument.finishPage(page);
    }else {
        Toast.makeText(MainActivity.this, &quot;Object Type not text&quot;, Toast.LENGTH_LONG).show();
        i++;
    }
}

Should get you one step closer to solving the issue. The squared behavior you're describing almost certainly comes from nested loops.

英文:

Simply removing the outermost for loop, i.e replacing:

for (int i=0; i &lt; pageModelArrayList.size(); i++){
for(PDFPageModel filledData : pageModelArrayList){
filledData.getPageData();
filledData.getType();
if(filledData.getType() == &quot;Text&quot;){
//create a page info description
PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(595, 842, i+1).create();
//start a page
PdfDocument.Page page = pdfDocument.startPage(pageInfo);
//writing to new page
Paint paint = new Paint();
//canvas used to write to page, getting object data from inputted text
String myString = filledData.getPageData();
//setting where to start text on the page
int x = 10, y = 25;
//multi line loop
for(String line:myString.split(&quot;\n&quot;)){
page.getCanvas().drawText(line, x, y, paint);
y+=paint.descent()-paint.ascent();
}
//finish page
pdfDocument.finishPage(page);
}else {
Toast.makeText(MainActivity.this, &quot;Object Type not text&quot;, Toast.LENGTH_LONG).show();
}
}
}

with:

    int i=0;
for(PDFPageModel filledData : pageModelArrayList){
filledData.getPageData();
filledData.getType();
if(filledData.getType() == &quot;Text&quot;){
//create a page info description
PdfDocument.PageInfo pageInfo = new PdfDocument.PageInfo.Builder(595, 842, i+1).create();
//start a page
PdfDocument.Page page = pdfDocument.startPage(pageInfo);
//writing to new page
Paint paint = new Paint();
//canvas used to write to page, getting object data from inputted text
String myString = filledData.getPageData();
//setting where to start text on the page
int x = 10, y = 25;
//multi line loop
for(String line:myString.split(&quot;\n&quot;)){
page.getCanvas().drawText(line, x, y, paint);
y+=paint.descent()-paint.ascent();
}
//finish page
pdfDocument.finishPage(page);
}else {
Toast.makeText(MainActivity.this, &quot;Object Type not text&quot;, Toast.LENGTH_LONG).show();
i++
}

Should get you one step closer to solving the issue. The squared behaviour you're describing almost certainly comes from nested loops.

huangapple
  • 本文由 发表于 2020年8月2日 17:40:42
  • 转载请务必保留本文链接：https://go.coder-hub.com/63214480.html
  • android
  • for-loop
  • java
  • pdf
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