Question

我在从之前的活动中获取值时遇到问题。我正在创建一个使用彩色按钮作为选择的测验应用。基本上，你只需要选择指令所说的按钮。这是代码：

public class EasyMode2Activity extends AppCompatActivity {
    Intent g = getIntent(); // get values from EasyMode1Activity.java
    public int score = g.getIntExtra("score", 5);
    public final int questionTotal = 5;
    public int question = g.getIntExtra("questions", 5);
    public int questionsAnswered = g.getIntExtra("questionsAnswered", 5);

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_easy_mode2);

        Button btn4 = (Button) findViewById(R.id.button4);
        Button btn5 = (Button) findViewById(R.id.button5);
        Button btn6 = (Button) findViewById(R.id.button6);

        btn4.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                question++;
                TextView scoreText = (TextView) findViewById(R.id.txtScore2);
                scoreText.setText(scoreText.getText() + "" +score);

                toResults(view);
            }
        });

        btn5.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                question++;
                TextView scoreText = (TextView) findViewById(R.id.txtScore2);
                scoreText.setText(scoreText.getText() + "" +score);

                toResults(view);
            }
        });

        btn6.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                question++;
                score++;
                TextView scoreText = (TextView) findViewById(R.id.txtScore2);
                scoreText.setText(scoreText.getText() + "" +score);
                questionsAnswered++;
                toResults(view);
            }
        });

        TextView questionTxt = (TextView) findViewById(R.id.txtquestion_number2);
        questionTxt.setText(questionTxt.getText() + " " +question+ " of " +questionTotal);

        final Chronometer timer = (Chronometer) findViewById(R.id.chronometer2);
        timer.start();

        Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
        setSupportActionBar(toolbar);
        getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    }

    public void toResults (View view) {
        Intent i = new Intent (this, ResultsActivity.class);
        Bundle b = new Bundle();
        b.putInt("score", score); // store the score
        b.putInt("questionsAnswered", questionsAnswered);
        b.putInt("question", question);
        i.putExtras(b); // put your score to your next intent
        startActivity(i);
    }

}

另外，我尝试在手机上运行该应用程序。它崩溃了。之前的活动（EasyModeActivity1 - 它们具有类似的代码，但它具有初始值的例外）可以工作但是一旦我点击该活动中的任何按钮，它应该转到EasyModeActivity2但它会崩溃。

Answer 1

放置这些行：

Intent g = getIntent(); // get values from EasyMode1Activity.java
public int score = g.getIntExtra("score", 5);
public final int questionTotal = 5;
public int question = g.getIntExtra("questions", 5);
public int questionsAnswered = g.getIntExtra("questionsAnswered", 5);

在onCreate里面是这样的：

Intent g = getIntent(); // get values from EasyMode1Activity.java
if (g != null) {
    score = g.getIntExtra("score", 5);
    questionTotal = 5;
    question = g.getIntExtra("questions", 5);
    questionsAnswered = g.getIntExtra("questionsAnswered", 5);
}

就在这一行之后：

setContentView(R.layout.activity_easy_mode2);

传球时：

Intent intent = new Intent(this, DestinationActivity.class)
intent.putExtra("myStringKey", "My String value");//pass string
intent.putExtra("myBooleanKey", false);//pass boolean
intent.putExtra("myIntKey", 50);//pass integer
intent.putExtra("score", 50);
intent.putExtra("unanswered", 100);
intent.putExtra("questionsAnswered", 15);
startActivity(intent);

从以前的活动中获取值时出错

1 个答案: