Question

从数据库中显示标题和图像的最佳方法是什么？我只想一次显示一个数据行/记录，然后单击下一个按钮以显示下一个数据行/记录。我无法确定哪种视图控件最好？我看过很多与listview相关的例子。

id |标题|图像

1 Spring image1.blob 2夏天image2.blob 3冬季image3.blob

logcat的

06-07 04:33:06.213: E/Trace(950): error opening trace file: No such file or directory (2)
06-07 04:33:08.041: D/Insert:(950): Inserting ..
06-07 04:33:08.150: D/AndroidRuntime(950): Shutting down VM
06-07 04:33:08.150: W/dalvikvm(950): threadid=1: thread exiting with uncaught exception (group=0x40a71930)
06-07 04:33:08.171: E/AndroidRuntime(950): FATAL EXCEPTION: main
06-07 04:33:08.171: E/AndroidRuntime(950): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.sqlitedemoactivity/com.example.sqlitedemoactivity.SQLiteDemoActivity}: java.lang.NullPointerException
06-07 04:33:08.171: E/AndroidRuntime(950):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2180)
06-07 04:33:08.171: E/AndroidRuntime(950):  at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2230)
06-07 04:33:08.171: E/AndroidRuntime(950):  at android.app.ActivityThread.access$600(ActivityThread.java:141)
06-07 04:33:08.171: E/AndroidRuntime(950):  at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1234)
06-07 04:33:08.171: E/AndroidRuntime(950):  at android.os.Handler.dispatchMessage(Handler.java:99)
06-07 04:33:08.171: E/AndroidRuntime(950):  at android.os.Looper.loop(Looper.java:137)
06-07 04:33:08.171: E/AndroidRuntime(950):  at android.app.ActivityThread.main(ActivityThread.java:5041)
06-07 04:33:08.171: E/AndroidRuntime(950):  at java.lang.reflect.Method.invokeNative(Native Method)
06-07 04:33:08.171: E/AndroidRuntime(950):  at java.lang.reflect.Method.invoke(Method.java:511)
06-07 04:33:08.171: E/AndroidRuntime(950):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:793)
06-07 04:33:08.171: E/AndroidRuntime(950):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:560)
06-07 04:33:08.171: E/AndroidRuntime(950):  at dalvik.system.NativeStart.main(Native Method)
06-07 04:33:08.171: E/AndroidRuntime(950): Caused by: java.lang.NullPointerException
06-07 04:33:08.171: E/AndroidRuntime(950):  at com.example.sqlitedemoactivity.SQLiteDemoActivity.onCreate(SQLiteDemoActivity.java:37)
06-07 04:33:08.171: E/AndroidRuntime(950):  at android.app.Activity.performCreate(Activity.java:5104)
06-07 04:33:08.171: E/AndroidRuntime(950):  at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1080)
06-07 04:33:08.171: E/AndroidRuntime(950):  at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2144)
06-07 04:33:08.171: E/AndroidRuntime(950):  ... 11 more
06-07 04:33:15.283: I/Process(950): Sending signal. PID: 950 SIG: 9

我的代码

private void setNewData(int position){
        textview1 = (TextView)findViewById(R.id.textview1);
        List<Contact> contacts = db.getContact(position) ;
        for (Contact cn : contacts) {
            String log = "ID:" + cn.getID() + " Name: " + cn.getName();
            // Writing Contacts to log
            Log.d("Name: ", log); 
            textview1.setText(cn.getName());

        }
    }

按钮点击代码

button1.setOnClickListener(new OnClickListener(){
                @Override
                public void onClick(View v) {
                    //increment the counter (which is keeps track of what position we are displaying.
                    counter = counter+1;
                    //call method to update the view with the next items position
                    setNewData(counter);
                }

            });

Answer 1

将数据库中的所有项目加载到数组中。然后使用一些简单的代码来跟踪您当前正在显示的项目。单击该按钮时，更新视图与下一项文本/图像。下面是一些示例代码（它不会编译，但会给你一个想法）

public class Thing{
    public String imageURL;
    public String text;
}

private List<Thing> myThings;
private int counter=0;
private Button nextButton;

nextButton.setOnClickListener(new OnClickListener() {
        @Override public void onClick(View v) {
            //increment the counter (which is keeps track of what position we are displaying.
            counter = counter+1;
            //call method to update the view with the next items position
            setNewData(counter);
        }
    });


 private void setNewData(int position){
    /*
     * Get the data from the list of the new position
     */
    String image = myThings.get(position).imageURL;
    String text = myThings.get(position).text;
    myTextView.setText(text);
    myImageView.loadImage(image);
}

Android：一次从数据库中显示一行（文本和图像），然后单击下一行的下一行按钮

1 个答案: