android - 如何根据存储在 sqlite 中的一些单独值更改 MPandroidCharts 中的条形颜色？
问题描述
如果有一个 SQLite 存储 3 个值名称、学分、铺位。我有一个带有 x-axis:names,y-axis:bunks 的 mpandroid 条形图。我想根据每个条目的信用更改单个条形颜色或添加限制线，存储在 SQLite 中。这可能吗？我是新手，请帮帮我。
public class Myhelper extends SQLiteOpenHelper {
public static final String DATABASE_NAME="mydatabase.db";
public static final String TABLE_NAME="mytable";
public static final String COLUMN_ID="_id";
public static final String COL_1="NAME";
public static final String COL_2="CREDIT";
public static final String COL_3="BUNKS";
public static final String[] COLUMNS ={COLUMN_ID,COL_1,COL_2,COL_3};
Context con;
public Myhelper(Context context) {
super(context, DATABASE_NAME, null, 1);
con = context;
}
@Override
public void onCreate(SQLiteDatabase db) {
String createTable= "CREATE TABLE " + TABLE_NAME + " (" + COLUMN_ID +" INTEGER PRIMARY KEY AUTOINCREMENT, " + " NAME TEXT, CREDIT TEXT, BUNKS INTEGER )";
db.execSQL(createTable);
Toast.makeText(con,"table created",Toast.LENGTH_SHORT).show();
}
@Override
public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
db.execSQL("DROP TABLE IF EXISTS "+ TABLE_NAME);
onCreate(db);
}
public boolean insertData(String x,String y,int z){
SQLiteDatabase db=this.getWritableDatabase();
ContentValues contentValues = new ContentValues();
contentValues.put(COL_1, String.valueOf(x));
contentValues.put(COL_2,String.valueOf(y));
contentValues.put(COL_3,z);
long result = db.insert(TABLE_NAME, null, contentValues);
if (result == -1) {
return false;
} else {
return true;
}
}
public ArrayList<String> queryXdata(){
ArrayList<String> xnewdata= new ArrayList<String>();
String query = "SELECT "+ COL_1 + " FROM " + TABLE_NAME;
SQLiteDatabase db=this.getWritableDatabase();
Cursor cursor= db.rawQuery(query,null);
for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()){
xnewdata.add(cursor.getString(cursor.getColumnIndex(COL_1)));
}
cursor.close();
return xnewdata;
}
public ArrayList<Integer> queryYdata(){
ArrayList<Integer> ynewdata= new ArrayList<Integer>();
String query = "SELECT "+ COL_3+ " FROM " + TABLE_NAME;
SQLiteDatabase db=this.getWritableDatabase();
Cursor cursor= db.rawQuery(query,null);
for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()){
ynewdata.add(cursor.getInt(cursor.getColumnIndex(COL_3)));
}
cursor.close();
return ynewdata;
}
public ArrayList<Integer> queryZdata(){
ArrayList<Integer> znewdata= new ArrayList<Integer>();
String query = "SELECT "+ COL_2+ " FROM " + TABLE_NAME;
SQLiteDatabase db=this.getWritableDatabase();
Cursor cursor= db.rawQuery(query,null);
for (cursor.moveToFirst(); !cursor.isAfterLast(); cursor.moveToNext()){
znewdata.add(((cursor.getColumnIndex(COL_2))));
}
cursor.close();
return znewdata;
}
public attendence getdetails(long id){
SQLiteDatabase db = this.getWritableDatabase();
String query= "SELECT" + COL_2+" FROM " + TABLE_NAME +" WHERE _id=" + id;
Cursor cursor= db.rawQuery(query,null);
attendence attendence1= new attendence();
if (cursor.getCount()>0){
cursor.moveToFirst();
attendence1.setSubname(cursor.getString(cursor.getColumnIndex(COL_1)));
attendence1.setCredit(cursor.getString(cursor.getColumnIndex(COL_2)));
attendence1.setBunks(cursor.getInt(cursor.getColumnIndex(COL_3)));
}
return attendence1;
}
public void delete(long id,Context context){
SQLiteDatabase db=this.getWritableDatabase();
db.execSQL("DELETE FROM "+TABLE_NAME+" WHERE _id='"+id+"'");
Toast.makeText(context,"delted",Toast.LENGTH_SHORT).show();
}
public List<attendence> list(String filter){
String query;
if (filter.equals("")){
query = "SELECT * FROM " + TABLE_NAME ;
}
else {
query= " SELECT * FROM " + TABLE_NAME ;
}
List<attendence> linkedlist = new LinkedList<>();
SQLiteDatabase db = this.getWritableDatabase();
Cursor cursor = db.rawQuery(query,null);
attendence attendence;
if (cursor.moveToFirst()){
do {
attendence = new attendence();
attendence.setId(cursor.getLong(cursor.getColumnIndex(COLUMN_ID)));
attendence.setSubname(cursor.getString(cursor.getColumnIndex(COL_1)));
attendence.setCredit(cursor.getString(cursor.getColumnIndex(COL_2)));
attendence.setBunks(cursor.getInt(cursor.getColumnIndex(COL_3)));
linkedlist.add(attendence);
}
while (cursor.moveToNext());
}
return linkedlist;
}
public int getbunk(long id) {
SQLiteDatabase db = this.getReadableDatabase();
Cursor cursor = db.rawQuery("SELECT * FROM " + TABLE_NAME + " WHERE " + COLUMN_ID + " = " + String.valueOf(id), null);
int output = -1;
if (cursor != null) {
if (cursor.moveToFirst()) {
output = cursor.getInt(cursor.getColumnIndex(COL_3));
}
cursor.close();
}
return output;
}
public int updatebunk(long id){
SQLiteDatabase db = this.getWritableDatabase();
int bunk = getbunk(id);
if (bunk<0){
Log.i("error", "updatebunk:below 0 ");
}
int bunkinc= ++bunk;
ContentValues contentValues= new ContentValues();
contentValues.put(COL_3, bunkinc);
db.update(TABLE_NAME,contentValues,COLUMN_ID+ "=?",new String[]{String.valueOf(id)});
db.close();
return bunkinc;
}
public int updatebunkdelete(long id){
SQLiteDatabase db = this.getWritableDatabase();
int bunk = getbunk(id);
int bunkdec= --bunk;
ContentValues contentValues= new ContentValues();
contentValues.put(COL_3,bunkdec);
db.update(TABLE_NAME,contentValues,COLUMN_ID+ "=?",new String[]{String.valueOf(id)});
db.close();
return bunkdec;
}
}
我的活动（条形图）
public void addData(){
ArrayList<BarEntry> yVals = new ArrayList<>();
for (int i=0; i<myhelper.queryYdata().size(); i++){
yVals.add(new BarEntry((((myhelper.queryYdata().get(i)))),i));
}
ArrayList<String> xvals= new ArrayList<>();
for (int i=0;i<myhelper.queryXdata().size();i++){
xvals.add(myhelper.queryXdata().get(i));
}
MyBarDataset dataSet= new MyBarDataset(yVals,"");
dataSet.setColors(new int[]{ContextCompat.getColor(mcontext,R.color.green),
ContextCompat.getColor(mcontext,R.color.yellow),
ContextCompat.getColor(mcontext,R.color.red)});
BarData data = new BarData(xvals,dataSet);
mychart.setData(data);
//bar custamization
mychart.animateY(1000);
mychart.setDrawGridBackground(false);
mychart.setBackgroundColor(Color.WHITE);
mychart.getXAxis().setPosition(XAxis.XAxisPosition.BOTTOM);
mychart.getAxisRight().setEnabled(false);
mychart.setDescription("");
mychart.getLegend().setEnabled(false);
mychart.getXAxis().setDrawGridLines(false);
mychart.getAxisLeft().setDrawGridLines(false);
mychart.getAxisLeft().setStartAtZero(true);
mychart.getAxisLeft().setAxisMinValue(0);
}
public class MyBarDataset extends BarDataSet{
public MyBarDataset(List<BarEntry> yVals, String label) {
super(yVals, label);
}
@Override
public int getColor(int index){
if (getEntryForXIndex(index).getVal()<8){
return mColors.get(0);
}
else if (getEntryForXIndex(index).getVal()<13)
return mColors.get(1);
else
return mColors.get(2);
}
}
解决方案
据我了解，您希望基于 绘制条形图，bunk但基于credits. 使用自定义条形数据集是正确的做法，只需稍作修改即可。下面的代码得到你所描述的。
我所做的更改：
- 无法将名称列表传递给
BarData，请改用轴值格式化程序 - 将自定义条形数据集更改为也保存
credits数组。不确定您的getEntryForXIndex方法是否在其他地方定义，但它不在您发布的代码中。 - 删除了不推荐使用的调用和无效的语法（不能调用
setDescription("");）
如果这不是您要查找的内容，请使用有关您所看到的内容等的更多详细信息更新问题...据我所知，问题是关于图表而不是关于 SQL 数据库。
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
BarChart chart = findViewById(R.id.test_chart);
// Some made up data - replace these with your
// queryYdata, queryXdata, and queryZdata methods
String[] names = new String[]{"foo","bar","fiz","bam","boo"};
List<Float> credits = new ArrayList<>(Arrays.asList(1f,9f,2.5f,15f,50f));
float[] bunks = new float[]{10f,15f,16f,20f,5f};
List<BarEntry> entries = new ArrayList<>();
for(int i = 0; i < bunks.length; ++i) {
entries.add(new BarEntry(i, bunks[i]));
}
float textSize = 16f;
MyBarDataset dataSet = new MyBarDataset(entries, "data", credits);
dataSet.setColors(ContextCompat.getColor(this,R.color.green),
ContextCompat.getColor(this,R.color.yellow),
ContextCompat.getColor(this,R.color.red));
BarData data = new BarData(dataSet);
data.setDrawValues(false);
data.setBarWidth(0.9f);
chart.setData(data);
chart.setFitBars(true);
chart.getXAxis().setValueFormatter(new IndexAxisValueFormatter(names));
chart.getXAxis().setPosition(XAxis.XAxisPosition.BOTTOM);
chart.getXAxis().setTextSize(textSize);
chart.getAxisLeft().setTextSize(textSize);
chart.setExtraBottomOffset(10f);
chart.getAxisRight().setEnabled(false);
Description desc = new Description();
desc.setText("");
chart.setDescription(desc);
chart.getLegend().setEnabled(false);
chart.getXAxis().setDrawGridLines(false);
chart.getAxisLeft().setDrawGridLines(false);
chart.invalidate();
}
public class MyBarDataset extends BarDataSet{
private List<Float> credits;
MyBarDataset(List<BarEntry> yVals, String label, List<Float> credits) {
super(yVals, label);
this.credits = credits;
}
@Override
public int getColor(int index){
float c = credits.get(index);
if (c < 8){
return mColors.get(0);
}
else if (c < 13) {
return mColors.get(1);
}
else {
return mColors.get(2);
}
}
}
编辑：关于 SQL 数据库的旁白——不要在循环内调用queryXData和！queryYData这将在每次循环迭代中提取整个数据数组，然后在循环本身内部再次提取（非常昂贵）。只需使用这样的东西：
ArrayList<BarEntry> yVals = new ArrayList<>();
ArrayList<Integer> yData = myhelper.queryYdata();
for (int i=0; i<yData.size(); i++){
yVals.add(new BarEntry(i,yData.get(i)));
}
ArrayList<String> xData = myhelper.queryXdata();
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