android获取数据库查询的结果

参考：https://www.xuebuyuan.com/3244495.html

原来错误的程序，app会崩溃（请大神指点错误的原因是啥？_(:з)∠)_）

1 btn_search.setOnClickListener(new View.OnClickListener() {
2 @Override
3 public void onClick(View v) {
4 String key = et_username.getText().toString();
5 Cursor cursor = dbOpenHelper.getReadableDatabase().query("tb_user",null,"username=?",new String[]{key}, null,null,null);
6
7 if (cursor.getCount() == 0) {
8 Toast.makeText(MainActivity.this,"很遗憾，没有相关记录",Toast.LENGTH_SHORT).show();
9 } else {
10 // while (cursor.moveToNext()) {
11 // Log.i("cccccccccc", cursor.getString(1) " " cursor.getString(2));
12 // }
13 Log.i("dddddddd",cursor.getString(1));
14 }
15 }
16 });

改正后的程序，用循环来输出

1 btn_search.setOnClickListener(new View.OnClickListener() {
2 @Override
3 public void onClick(View v) {
4 String key = et_username.getText().toString();
5 Cursor cursor = dbOpenHelper.getReadableDatabase().query("tb_user",null,"username=?",new String[]{key}, null,null,null);
6
7 if (cursor.getCount() == 0) {
8 Toast.makeText(MainActivity.this,"很遗憾，没有相关记录",Toast.LENGTH_SHORT).show();
9 } else {
10 while (cursor.moveToNext()) {
11 Log.i("cccccccccc", cursor.getString(1) " " cursor.getString(2));
12 }
13 // Log.i("dddddddd",cursor.getString(1));
14 }
15 }
16 });