下面是一个使用Android谷歌地图API绘制单个折线和多个折线的代码示例：

单个折线：

import android.graphics.Color;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Polyline;
import com.google.android.gms.maps.model.PolylineOptions;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private GoogleMap mMap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);

        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;

        // 添加折线
        PolylineOptions polylineOptions = new PolylineOptions()
                .add(new LatLng(51.5, -0.1))
                .add(new LatLng(40.7, -74.0))
                .add(new LatLng(34.0, -118.2))
                .color(Color.RED);
        Polyline polyline = mMap.addPolyline(polylineOptions);

        // 移动地图视图到折线的中心
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(polyline.getPoints().get(polyline.getPoints().size() / 2), 10));
    }
}

多个折线：

import android.graphics.Color;
import android.support.v4.app.FragmentActivity;
import android.os.Bundle;

import com.google.android.gms.maps.CameraUpdateFactory;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import com.google.android.gms.maps.model.LatLng;
import com.google.android.gms.maps.model.Polyline;
import com.google.android.gms.maps.model.PolylineOptions;

public class MapsActivity extends FragmentActivity implements OnMapReadyCallback {

    private GoogleMap mMap;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_maps);

        SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
                .findFragmentById(R.id.map);
        mapFragment.getMapAsync(this);
    }

    @Override
    public void onMapReady(GoogleMap googleMap) {
        mMap = googleMap;

        // 添加第一个折线
        PolylineOptions polylineOptions1 = new PolylineOptions()
                .add(new LatLng(51.5, -0.1))
                .add(new LatLng(40.7, -74.0))
                .color(Color.RED);
        Polyline polyline1 = mMap.addPolyline(polylineOptions1);

        // 添加第二个折线
        PolylineOptions polylineOptions2 = new PolylineOptions()
                .add(new LatLng(34.0, -118.2))
                .add(new LatLng(48.8, 2.3))
                .color(Color.BLUE);
        Polyline polyline2 = mMap.addPolyline(polylineOptions2);

        // 移动地图视图到第一个折线的中心
        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(polyline1.getPoints().get(polyline1.getPoints().size() / 2), 5));
    }
}

请确保在AndroidManifest.xml文件中添加以下权限：

并在build.gradle文件中添加以下依赖项：

implementation 'com.google.android.gms:play-services-maps:17.0.1'