java - 如何在不返回 size = 0 的情况下获取 ArrayList 的值？

Question

当我获取 arraylist 的值时，我得到 size = 0。我在 Class Screen1 中启动 ArrayList，但我无法获取 Class Screen2 cont 的值。

public class Variables {

public Variables() {
}

private int cont = 0;
private int correct = 0;


public int getCont(){
    return cont;
}
public void setCont(int cont){
    this.cont = cont;
}

public int getCorrect(){
    return correct;
}
public void setCorrect(int correct){
    this.correct = correct;
}}

类屏幕1

public class Screen1 extends ActionBarActivity {


Variables variables = new Variables();
ArrayList<Variables> variablesArrayList = new ArrayList<Variables>();
public int cont;




@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_screen1);


    variables.setCorrect(1);
    variables.setCont(1);
    variablesArrayList.add(variables);

}


public void sendTela1(View view){
    cont = variables.getCont();

    cont++;

    variablesArrayList.get(0).setCont(cont);

    }

}

类屏幕 2

这个类我正在尝试获取 ArrayList 的值

public class Screen2 extends ActionBarActivity {

Variables variables = new Variables();
ArrayList<Variables> variablesArrayList = new ArrayList<Variables>();
int cont;
ImageView progressbar;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_screen2);


    progressbar = (ImageView) findViewById(R.id.progressbar);

    //this line, the arraylist is returning size = 0
    cont = variablesArrayList.get(1);


    switch (cont){
        case 1:
            progressbar.setImageResource(R.drawable.progressbar1);
            break;

        case 2:
            progressbar.setImageResource(R.drawable.progressbar2);
            break;
        case 3:
            progressbar.setImageResource(R.drawable.progressbar3);
            break;
        case 4:
            progressbar.setImageResource(R.drawable.progressbar4);
            break;
        case 5:
            progressbar.setImageResource(R.drawable.progressbar5);
            break;
    }}

Answer 1

您得到的返回大小为 0，因为在 screen2 中您在创建新列表时执行的 Activity :ArrayList<Variables> variablesArrayList = new ArrayList<Variables>();

要解决此问题，您需要传递在 screen1 中创建的数组列表进入screen2 .您将必须实现 parcelable , 但这将允许您使用 intents 传递数据和 bundles .