Question

我有3个班级A，B，C。

A类将3个值传递给B类，B类将3个值传递给C类。在C级我有一个后退按钮如果我点击这个后退按钮我想恢复我的活动B.

我是Android新手;我对活动生命周期知之甚少。提前谢谢。

这是我的代码。

public class A extends Activity
{
    EditText one,two,three;Button sub;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        setContentView(R.layout.one);
        this.onWindowFocusChanged(true);
        one=(EditText)findviewById(R.id.one);
        two=(EditText)findviewById(R.id.one);
        three=(EditText)findviewById(R.id.one);
        addListenerOnButton();
    }
    public void addListenerOnButton() 
    {
        // TODO Auto-generated method stub
        sub.setOnClickListener(new OnClickListener() 
        {
            @Override
            public void onClick(View v) 
            {
                Intent i = new Intent(A.this, B.class);
                Bundle b=new Bundle();
                b.putString("one",one.getText().toString());
                b.putString("two",two.getText().toString());
                b.putString("three",three.getText().toString());
                b.putExtras(b);
                startActivity(i);
            }
        });
    }
}

这是B类活动

public class B extends Activity
{
    EditText one,two,three;Button sub;String one1,two1,three1;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        setContentView(R.layout.two);
        this.onWindowFocusChanged(true);
        one=(EditText)findviewById(R.id.one);
        two=(EditText)findviewById(R.id.one);
        three=(EditText)findviewById(R.id.one);
        Bundle b = this.getIntent().getExtras();
        one1=b.getString("one");
        one.setText(one1);
        two1=b.getString("two");
        two.setText(two1);
        three1=b.getString("three");
        three.setText(three1);
        addListenerOnButton();
    }
    public void addListenerOnButton() 
    {
        // TODO Auto-generated method stub
        sub.setOnClickListener(new OnClickListener() 
        {
            @Override
            public void onClick(View v) 
            {
                Intent i = new Intent(B.this, C.class);
                Bundle b=new Bundle();
                b.putString("one",one.getText().toString());
                b.putString("two",two.getText().toString());
                b.putString("three",three.getText().toString());
                b.putExtras(b);
                startActivity(i);
            }
        });
    }
}

这是C类活动（应用程序崩溃）

public class C extends Activity
{
    EditText one,two,three;Button sub,back;String one1,two1,three1;

    @Override
    protected void onCreate(Bundle savedInstanceState) 
    {
        super.onCreate(savedInstanceState);
        this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
        setContentView(R.layout.three);
        this.onWindowFocusChanged(true);
        one=(EditText)findviewById(R.id.one);
        two=(EditText)findviewById(R.id.one);
        three=(EditText)findviewById(R.id.one);
        Bundle b = this.getIntent().getExtras();
        one1=b.getString("one");
        one.setText(one1);
        two1=b.getString("two");
        two.setText(two1);
        three1=b.getString("three");
        three.setText(three1);
        addListenerOnButton();
    }
    public void addListenerOnButton() 
    {
        back.setOnClickListener(new OnClickListener() 
        {
            @Override
            public void onClick(View v) 
            {
                //Clicking back button i want to resume the activity b class but its getting crashed
                Intent i = new Intent(C.this, B.class);
                startActivity(i);
            }
        });
    }
}

每当我点击此后退按钮时，应用程序崩溃，而不是恢复我的活动B.

Answer 1

要关闭C活动并恢复最后一个活动，请使用finish();

例如，将finish();放入后退按钮侦听器

Answer 2

在Activity C类中用这个替换你的后退按钮监听器：

back.setOnClickListener(new OnClickListener() 
{
    @Override
    public void onClick(View v) 
    {
        finish();
    }
}

它将关闭您当前的活动（C），从而恢复您之前处于活动状态的活动（B）。

Answer 3

像这样使用

public class Main1Activity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main1);
        ((TextView)findViewById(R.id.txt)).setOnClickListener(new OnClickListener() {

            @Override
            public void onClick(View v) {
                // TODO Auto-generated method stub
                onBackPressed();
            }
        });
    }
    @Override
    public void onBackPressed() {
        // TODO Auto-generated method stub
        super.onBackPressed();
    }
}

如何从活动C恢复活动B？

3 个答案: