Android Studio，根据另一个 Activity 的 int 值设置文本可见性

Question

我正在尝试根据另一个 Activity 的整数值在一个 Activity 中设置 TextView 可见性。理想情况下，我试图将 imgID 的值设置为一个 int，并且根据整数值，第二个 Activity 设置 10 个 TextView 的可见性。每当在主要 Activity (图片)中单击 ImageView 时，imgID 值都应该设置为一个数字。但是，当我运行该程序时，无论我单击哪张图片，所有文本都会出现。这是我在一门课上的第二个实验，我有点挣扎，所以如果我错过了一些明显的东西，我深表歉意。此外，感谢任何其他提示或关于我错过的其他事情的信息。感谢您提前帮助!

代码如下:

主要 Activity :

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.content.Intent;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.ImageView;

public class Pictures extends AppCompatActivity {
    static int imgID;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_pictures);

        //register click event listener to image view(I hope :)
        ImageView imgB = (ImageView) findViewById(R.id.imageViewB);
        ImageView imgH = (ImageView) findViewById(R.id.imageViewH);
        ImageView imgM = (ImageView) findViewById(R.id.imageViewM);
        ImageView imgD = (ImageView) findViewById(R.id.imageViewD);
        ImageView imgS = (ImageView) findViewById(R.id.imageViewS);
        imgB.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {
                //if imgB clicked, set imgID to 1 and so on...
                 imgID = 1;
                startActivity(new Intent(Pictures.this, Lab2App2.class));
            }
        });


        imgD.setOnClickListener(new OnClickListener() {


            @Override
            public void onClick(View v) {
                imgID = 2;
                startActivity(new Intent(Pictures.this, Lab2App2.class));
            }
        });



        imgH.setOnClickListener(new OnClickListener() {


            @Override
            public void onClick(View v) {
                imgID = 3;
                startActivity(new Intent(Pictures.this, Lab2App2.class));
            }
        });


        imgM.setOnClickListener(new OnClickListener() {


            @Override
            public void onClick(View v) {
                imgID = 4;
                startActivity(new Intent(Pictures.this, Lab2App2.class));
            }
        });
        imgS.setOnClickListener(new OnClickListener() {


            @Override
            public void onClick(View v) {
                imgID = 5;
                startActivity(new Intent(Pictures.this, Lab2App2.class));
            }
        });

    }


    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_pictures, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);

    }




}

第二个 Activity :

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.widget.TextView;

public class Lab2App2 extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_lab2_app2);
        TextView campusB = (TextView)findViewById(R.id.text_campusB);
        TextView campusD = (TextView)findViewById(R.id.text_campusD);
        TextView campusH = (TextView)findViewById(R.id.text_campusH);
        TextView campusM = (TextView)findViewById(R.id.text_campusM);
        TextView campusS = (TextView)findViewById(R.id.text_campusH);
        if(Pictures.imgID == 1) {

            campusB.setVisibility(View.VISIBLE);
            campusD.setVisibility(View.GONE);
            campusH.setVisibility(View.GONE);
            campusM.setVisibility(View.GONE);
            campusS.setVisibility(View.GONE);

        }
        else if(Pictures.imgID == 2) {

            campusB.setVisibility(View.GONE);
            campusD.setVisibility(View.VISIBLE);
            campusH.setVisibility(View.GONE);
            campusM.setVisibility(View.GONE);
            campusS.setVisibility(View.GONE);

        }
        else if(Pictures.imgID == 3) {

            campusB.setVisibility(View.GONE);
            campusD.setVisibility(View.GONE);
            campusH.setVisibility(View.VISIBLE);
            campusM.setVisibility(View.GONE);
            campusS.setVisibility(View.GONE);

        }
        else if(Pictures.imgID == 4) {

            campusB.setVisibility(View.GONE);
            campusD.setVisibility(View.GONE);
            campusH.setVisibility(View.GONE);
            campusM.setVisibility(View.VISIBLE);
            campusS.setVisibility(View.GONE);

        }
        else if(Pictures.imgID == 5) {

            campusB.setVisibility(View.GONE);
            campusD.setVisibility(View.GONE);
            campusH.setVisibility(View.GONE);
            campusM.setVisibility(View.GONE);
            campusS.setVisibility(View.VISIBLE);

        }
    }

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.menu_lab2_app2, menu);
        return true;
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle action bar item clicks here. The action bar will
        // automatically handle clicks on the Home/Up button, so long
        // as you specify a parent activity in AndroidManifest.xml.
        int id = item.getItemId();

        //noinspection SimplifiableIfStatement
        if (id == R.id.action_settings) {
            return true;
        }

        return super.onOptionsItemSelected(item);
    }
}

Answer 1

在 android 中，通常您应该将 imgID 等参数传递给 Intent ，然后从新的 startet Activity 中获取这些值。

这里是一个简短的代码示例:

  Intent intent = new Intent(Pictures.this, Lab2App2.class);
       intent.putExtra("imgID", imgID);

        //startActivityForResult(intent, YOUR_RETURN_CODE);
        startActivity(intent); 

如果您使用 startActivitiyForResult() 调用 Activity ，则需要 RETURN_CODE，以便您知道哪个 Activity 返回了您的结果。

在 Lab2App2 Activity 中，您可以使用以下方法获取 int:

getIntent().getIntExtra("imgID",DEFAULT_VALUE);

直接访问静态变量不是一个好习惯。有很多不同的方法可以做到这一点。但这是最安全和最简单的解决方案......例如用于恢复实例状态等。始终建议使用 Intent 。

希望对您有所帮助。干杯