向多级可扩展 LisView 的每个子项添加 Toast [英] Adding Toast to Every ChildItem of a Multi Level Expandable LisView
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问题描述
我发现这个 multilevel expandable listview 对我的项目非常准确，但我也想为每三个级别(这是视图的最后一层)子项添加一个不同的 toast.我试过这个:
I found this multilevel expandable listview which is very accurate with my project, but I also want to add a different toast to every third level (which is the last layer of view) child items. I tried this:
expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
@Override
public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
Toast.makeText(thirdLevelq1.put(q1[0] this, "The first child" , Toast.LENGTH_LONG).show();
return false;
}
});
但它给出了错误.我什至尝试对每个 childItem 使用相同的 toast 文本，应用程序安装但当我打开适配器时崩溃.那么，如何正确添加它们?
But it gives error. I even tried to use same toast text to every childItem, app installed but crashed when I opened the adapter. So, how to add them properly?
Java:
package com.bacon.expandablelistview;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.widget.ExpandableListView;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
public class MainActivity extends AppCompatActivity {
private ExpandableListView expandableListView;
String[] parent = new String[]{"What is View?", "What is Layout?", "What is Dynamic Views?"};
String[] q1 = new String[]{"List View", "Grid View"};
String[] q2 = new String[]{"Linear Layout", "Relative Layout"};
String[] q3 = new String[]{"Recycle View"};
String[] des1 = new String[]{"A layout that organizes its children into a single horizontal or vertical row. It creates a scrollbar if the length of the window exceeds the length of the screen."};
String[] des2 = new String[]{"Enables you to specify the location of child objects relative to each other (child A to the left of child B) or to the parent (aligned to the top of the parent)."};
String[] des3 = new String[]{"This list contains linear layout information"};
String[] des4 = new String[]{"This list contains relative layout information,Displays a scrolling grid of columns and rows"};
String[] des5 = new String[]{"Under the RecyclerView model, several different components work together to display your data. Some of these components can be used in their unmodified form; for example, your app is likely to use the RecyclerView class directly. In other cases, we provide an abstract class, and your app is expected to extend it; for example, every app that uses RecyclerView needs to define its own view holder, which it does by extending the abstract RecyclerView.ViewHolder class."};
LinkedHashMap<String, String[]> thirdLevelq1 = new LinkedHashMap<>();
LinkedHashMap<String, String[]> thirdLevelq2 = new LinkedHashMap<>();
LinkedHashMap<String, String[]> thirdLevelq3 = new LinkedHashMap<>();
/**
* Second level array list
*/
List<String[]> secondLevel = new ArrayList<>();
/**
* Inner level data
*/
List<LinkedHashMap<String, String[]>> data = new ArrayList<>();
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//The problem starts here
expandableListView.setOnChildClickListener(new ExpandableListView.OnChildClickListener() {
@Override
public boolean onChildClick(ExpandableListView parent, View v, int groupPosition, int childPosition, long id) {
Toast.makeText(getApplicationContext(), "The first child", Toast.LENGTH_LONG).show();
return false;
}
});
setUpAdapter();
}
private void setUpAdapter() {
secondLevel.add(q1);
secondLevel.add(q2);
secondLevel.add(q3);
thirdLevelq1.put(q1[0], des1);
thirdLevelq1.put(q1[1], des2);
thirdLevelq2.put(q2[0], des3);
thirdLevelq2.put(q2[1], des4);
thirdLevelq3.put(q3[0], des5);
data.add(thirdLevelq1);
data.add(thirdLevelq2);
data.add(thirdLevelq3);
expandableListView = (ExpandableListView) findViewById(R.id.expandible_listview);
//passing three level of information to constructor
ThreeLevelListAdapter threeLevelListAdapterAdapter = new ThreeLevelListAdapter(this, parent, secondLevel, data);
expandableListView.setAdapter(threeLevelListAdapterAdapter);
expandableListView.setOnGroupExpandListener(new ExpandableListView.OnGroupExpandListener() {
int previousGroup = -1;
@Override
public void onGroupExpand(int groupPosition) {
if (groupPosition != previousGroup)
expandableListView.collapseGroup(previousGroup);
previousGroup = groupPosition;
}
});
}
}
提前致谢.
当我使用 Toast.makeText(getApplicationContext(), 第一个孩子"，Toast.LENGTH_LONG).show(); 时，它的崩溃日志说:
When I use Toast.makeText(getApplicationContext(), "The first child", Toast.LENGTH_LONG).show(); its crash logs says:
Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.widget.ExpandableListView.setOnChildClickListener(android.widget.ExpandableListView$OnChildClickListener)' on a null object reference
推荐答案
@Override
public void onFinalChildClick(int plpos, int slpos, int tlpos) {
String msg = "";
switch (tlpos) {
case 0:
msg = "Shakespear is a good poet";
break;
case 1:
msg = "Earth isn't flat";
break;
default:
msg = "Unknown";
}
Toast.makeText(this, msg, Toast.LENGTH_SHORT).show();
}
@Override
public void onFinalItemClick(String plItem, String slItem, String tlItem) {
String inMsg = plItem + ", " + slItem + ", " + tlItem;
String outMsg = "";
if (inMsg.equals("group 1, Child Level 1, A")){
outMsg = "Shakespear is a good poet";
} else if (inMsg.equals("group 1, Child Level 1, B")){
outMsg = "Earth isn't flat";
} else {
outMsg = "Unknown";
}
Toast.makeText(this, outMsg, Toast.LENGTH_SHORT).show();
}
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