Android onLayout() 和 AsyncTask() 不能一起工作

Question

我需要一个带有固定标题的可滚动表格，所以我关注了这个很棒的博客，一切都很好。

这个想法是使用一张表作为标题，一张表用于滚动视图中添加的内容，两者都在自定义的 LinearLayout 中。在自定义的LinearLayout中，我们将重写onLayout()来获取每行的最大宽度，并为标题和内容表的每行设置宽度。

这是活动及其布局：

package com.stylingandroid.ScrollingTable;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.TableLayout;
import android.widget.TableRow;

public class ScrollingTable extends LinearLayout
{
    public ScrollingTable( Context context )
    {
        super( context );
    }
public ScrollingTable( Context context, AttributeSet attrs )
{
    super( context, attrs );
}

@Override
protected void onLayout( boolean changed, int l, int t, int r, int b )
{
    super.onLayout( changed, l, t, r, b );

    TableLayout header = (TableLayout) findViewById( R.id.HeaderTable );
    TableLayout body = (TableLayout) findViewById( R.id.BodyTable );
    
    if (body.getChildCount() > 0 ) {
        TableRow bodyRow = (TableRow) body.getChildAt(0);
        TableRow headerRow = (TableRow) header.getChildAt(0);
        
        for ( int cellnum = 0; cellnum < bodyRow.getChildCount(); cellnum++ ){
            View bodyCell = bodyRow.getChildAt(cellnum);
            View headerCell = headerRow.getChildAt(cellnum);
            int bodyWidth = bodyCell.getWidth();
            int headerWidth = headerCell.getWidth();
            int max = Math.max(bodyWidth, headerWidth);
            TableRow.LayoutParams bodyParams = (TableRow.LayoutParams)bodyCell.getLayoutParams();
            bodyParams.width = max;
            TableRow.LayoutParams headerParams = (TableRow.LayoutParams)headerCell.getLayoutParams();
            headerParams.width = max;
        }       
    }
}
}

main.xml

 <?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical" 
    android:layout_width="fill_parent"
    android:layout_height="fill_parent">
    
    <com.stylingandroid.ScrollingTable.ScrollingTable
        android:layout_width="match_parent"
        android:orientation="vertical"
        android:layout_height="match_parent">
        
        <TableLayout 
            android:layout_height="wrap_content"
            android:layout_width="match_parent" 
            android:id="@+id/HeaderTable">
        </TableLayout>
        
        <ScrollView 
            android:layout_width="match_parent"
            android:layout_height="wrap_content">
            
            <TableLayout 
                android:layout_height="wrap_content"
                android:layout_width="match_parent" 
                android:id="@+id/BodyTable">
            </TableLayout>
            
        </ScrollView>
        
    </com.stylingandroid.ScrollingTable.ScrollingTable>
    
</LinearLayout>

主要活动

 package com.stylingandroid.ScrollingTable;

import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Color;
import android.os.AsyncTask;
import android.os.Bundle;
import android.widget.TableLayout;
import android.widget.TableRow;

    import android.widget.TextView;
    
    public class ScrollingTableActivity extends Activity
    {
        private String[][] tableData = {
                {"header11111111111", "header2","header3","header4"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
            

    {"column1", "column1",

"column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"},
                {"column1", "column1","column1","column1"}
        };
        /** Called when the activity is first created. */
        @Override
        public void onCreate( Bundle savedInstanceState )
        {
            super.onCreate( savedInstanceState );
            setContentView( R.layout.main );
            TableLayout tableHeader = (TableLayout)findViewById(R.id.HeaderTable);
            TableLayout tableBody = (TableLayout)findViewById(R.id.BodyTable);
            
        appendRows(tableHeader, tableBody, tableData);
}

private void appendRows(TableLayout tableHeader ,TableLayout tableContent, String[][] amortization) {
    int rowSize=amortization.length;
    int colSize=(amortization.length > 0)?amortization[0].length:0;
    for(int i=0; i<rowSize; i++) {
        TableRow row1 = new TableRow(this);
        
        for(int j=0; j<colSize; j++) {
            TextView c = new TextView(this);
            c.setText(amortization[i][j]);
            c.setPadding(3, 3, 3, 3);
            if (i == 0) {
                c.setTextColor(Color.BLACK);
            }
            row1.addView(c);
        }
        
        if (i == 0) { 
            row1.setBackgroundColor(Color.LTGRAY);
            tableHeader.addView(row1, new TableLayout.LayoutParams());
        } else {
            tableContent.addView(row1, new TableLayout.LayoutParams());
        }
    }
}

上面的代码工作完美（），但是，当我使用 AnysnTask 从服务器获取数据并稍后将数据添加到表中，我的自定义视图中的 onLayout() 不再起作用。我通过注销一些数字来模拟获取数据：

public void onCreate( Bundle savedInstanceState )
    {
        super.onCreate( savedInstanceState );
        setContentView( R.layout.main );
        
        new MyTask().execute();
    }
    
    private class MyTask extends AsyncTask<Void, Void, Void> {
        
        private ProgressDialog progressDialog;
        protected void onPreExecute() {
                progressDialog = ProgressDialog.show(ScrollingTableActivity.this,
                                  "", "Loading. Please wait...", true);
        }
        @Override
        protected Void doInBackground(Void... reportTypes) {
            for (int i = 0; i < 500; i++) { 
                System.out.println(i);
            } 
            return null;
        }
        @Override
        protected void onPostExecute(Void result) {
            progressDialog.dismiss();
            TableLayout tableHeader = (TableLayout)findViewById(R.id.HeaderTable);
            TableLayout tableBody = (TableLayout)findViewById(R.id.BodyTable);
            
            appendRows(tableHeader, tableBody, tableData);
        }
        
    }

因此，仅当我通过将其放入 onCreate() 方法中从主 UI 线程调用appendRows() 时，onLayout() 才起作用。如果我从另一个 UI 线程（在 AsyncTask 的 onPostExecute() 中）调用，则会调用 onLayout() （我通过创建一些日志来检查它），但它不会影响 GUI。我尝试了 invalidate()、forceLayout()、requestLayout() 但没有改变任何内容。

我认为我们需要调用一个方法来刷新 GUI，但不知道它是什么。

Answer 1

您可能想看看这个答案：
Android 动态设置 textview 布局宽度

但是，基本上，尝试设置每个 TextView 与标题相同。

这可能需要您将所有操作都执行两次，因为您可能需要让系统进行布局，因此使用 View.INVISIBLE，然后您将需要退出 AsyncTask，调用另一个 AsyncTask，因此布局工作可能会发生。

然后在第二个中，您可以获取不可见的表格，循环查找该列中的最大宽度，然后将该列中的所有 TextView 设置为最大。

这不是最好的解决方案，但应该可行。

我认为 AsyncTask 中的主要问题是需要完成布局，然后您可以进行修复。

Answer 2

我终于找到答案了，setColumnCollapsed()使表格布局刷新，但是我们需要将其放在另一个AsyncTask中，否则它将不起作用，奇怪:(。我把最新的代码放在这里，所以希望它有帮助此外，这只是解决方法，所以请随意发布您的答案（如果有）...

private class MyTask extends AsyncTask<Void, Void, Void> {

    private ProgressDialog progressDialog;
    protected void onPreExecute() {
            progressDialog = ProgressDialog.show(ScrollingTableActivity.this,
                              "", "Loading. Please wait...", true);
    }
    @Override
    protected Void doInBackground(Void... reportTypes) {
        for (int i = 0; i < 500; i++) { 
            System.out.println(i);
        } 
        return null;
    }
    @Override
    protected void onPostExecute(Void result) {
        progressDialog.dismiss();
        appendRows(tableHeader, tableBody, tableData);

        new My1Task().execute();
    }
}

private class My1Task extends AsyncTask<Void, Void, Void> {

    @Override
    protected Void doInBackground(Void... reportTypes) {
        return null;
    }

    @Override
    protected void onPostExecute(Void result) {
        tableHeader.setColumnCollapsed(0, false);
        tableBody.setColumnCollapsed(0, false);
    }
}

Answer 3

答案是您应该在 onCreate() 方法之外声明 TableLayouts 并在 onCreate() 中实例化它们。这是解决方案。效果很好。

public class ScrollingTableActivity extends Activity {
    TableLayout tableHeader;
    TableLayout tableBody;

    private String[][] tableData = {
            { "header11111111111", "header2", "header3", "header4" },
            { "column1", "column1", "column1", "column1" },
            { "column1", "column1", "column1", "column1" },
            { "column1", "column1", "column1", "column1" },
            { "column1", "column1", "column1", "column1" } };

    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        tableHeader = (TableLayout) findViewById(R.id.HeaderTable);
        tableBody = (TableLayout) findViewById(R.id.BodyTable);
        Log.d("ScrollingTable", "Before appendRows");
        //appendRows(tableHeader, tableBody, tableData);
        new MyTask().execute();
    }

    private void appendRows(TableLayout tableHeader, TableLayout tableContent,
            String[][] amortization) {
        int rowSize = amortization.length;
        int colSize = (amortization.length > 0) ? amortization[0].length : 0;
        for (int i = 0; i < rowSize; i++) {
            TableRow row1 = new TableRow(this);

            for (int j = 0; j < colSize; j++) {
                TextView c = new TextView(this);
                c.setText(amortization[i][j]);
                c.setPadding(3, 3, 3, 3);
                if (i == 0) {
                    c.setTextColor(Color.BLACK);
                }
                row1.addView(c);
            }

            if (i == 0) {
                row1.setBackgroundColor(Color.LTGRAY);
                tableHeader.addView(row1, new TableLayout.LayoutParams());
            } else {
                tableContent.addView(row1, new TableLayout.LayoutParams());
            }
        }
    }


    private class MyTask extends AsyncTask<Void, Void, Void> {

        private ProgressDialog progressDialog;
        protected void onPreExecute() {
                progressDialog = ProgressDialog.show(ScrollingTableActivity.this,
                                  "", "Loading. Please wait...", true);
        }
        @Override
        protected Void doInBackground(Void... reportTypes) {
            for (int i = 0; i < 500; i++) { 
                System.out.println(i);
            } 
            return null;
        }
        @Override
        protected void onPostExecute(Void result) {
            progressDialog.dismiss();
            TableLayout tableHeader = (TableLayout)findViewById(R.id.HeaderTable);
            TableLayout tableBody = (TableLayout)findViewById(R.id.BodyTable);

            appendRows(tableHeader, tableBody, tableData);
        }
    }
}