java - 如何从一个Activity中获取Switch值并显示在另一个Activity中

Question

我是 Android 应用程序开发的初学者。我只是想从一个 Activity 中获取 Switch 值并将其显示在另一个 Activity 中。但是我得到的输出是“null”。请帮助我。

问题1.java

public class Question1Activity extends AppCompatActivity {
Switch swi;
Button back1, next1;
String value = "NO";
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_question1);
    swi = (Switch) findViewById(R.id.Switch_Ques_1);
    back1 = (Button) findViewById(R.id.Button_back1);
    next1 = (Button) findViewById(R.id.Button_next1);
    swi.setOnCheckedChangeListener(new CompoundButton.OnCheckedChangeListener() {

        @Override
        public void onCheckedChanged(CompoundButton buttonView,
                                     boolean isChecked) {

            if (isChecked) {
                swi.setText("YES");
                value="YES";
                swi.setTextColor(Color.GREEN);
            } else {
                swi.setText("NO");
                value="NO";
                swi.setTextColor(Color.RED);
            }

        }
    });
    back1.setOnClickListener(new View.OnClickListener(){
        public void onClick(View view){
            Intent intent = new Intent(Question1Activity.this,LoginActivity.class);
            startActivity(intent);
        }
    });
    next1.setOnClickListener(new View.OnClickListener(){
        public void onClick(View view){
            Intent intent = new Intent(Question1Activity.this,Question2Activity.class);
            intent.putExtra("Ans1",swi.isChecked());
            startActivity(intent);
        }
    });
}
}

问题3.java

public class Question3Activity extends AppCompatActivity {
TextView t1;
private SQLiteDatabase database;
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_question3);
    t1 = (TextView) findViewById(R.id.result);
    Intent intent = getIntent();
    String s1 =(String) intent.getStringExtra("Ans1");
    String s2 = intent.getStringExtra("Ans2");
    t1.setText(s1+" "+s2);
}
}

Answer 1

写成:

 String r;
          if(swi.isChecked())
              r = "true";
          else 
              r= "false";
          intent.putExtra("Ans1",r);

代替

 intent.putExtra("Ans1",swi.isChecked());